Cassini/MIMI Data Analysis Center

XINCA Users Guide

 

 

Revision 1

 


Document Information

Document title:

Cassini/MIMI Data Analysis Center IDL Operations Software Users Guide

Document file name:

MIMI_XINCAUserGuide

Revision number:

1

Issued by:

JHU APL

Issue Date:

05/22/2014

Status:

Version 1

 

 


Revision History

Revision

Date

Author

Description of change

 

 

 

 


Table of Contents

1.    Objectives........................................................................................................... 1

2.    Scope..................................................................................................................... 1

3.    References............................................................................................................ 1

4.    Document Overview............................................................................................ 2

5.    How to Access MIMI Software............................................................................ 2

6.    MIMI Main Menu................................................................................................ 3

7.    XINCA Skymap and Thumbnail Programs...................................................... 4

7.1    XINCA Skymap and Thumbnail....................................................................... 5

7.2    Multi-XINCA Skymap and Thumbnail............................................................ 23

8.    Appendix........................................................................................................... 30

8.1    Saved XINCA Image Format For IDL Saveset or ASCII File........................... 30

 


Cassini/MIMI Data Analysis Center IDL Analysis Software Users Guide

1.    Objectives

This document presents the IDL XINCA Users Guide. The guide describes how to use XINCA and multi-XINCA IDL software that displays and accesses INCA sensor image data from the MIMI instrument on the Cassini spacecraft. The primary objective of this guide is to describe the menu functions, however the menu and plotting software program names are included as an aide for the advanced user who wants to run the programs manually.

 

2.    Scope

The programs described in this document are written in IDL. They are accessed from the MIMI main menu or from the IDL command prompt. The other analysis programs are described in the Cassini/MIMI Data Analysis Center Analysis User Guide.

 

3.    References

The references listed below provide additional information about the instrument, data files, and the plotting software. Reference 1, the Instrument Data User Guide, is the official guide to the MIMI instrument. It contains a great deal of information on the instrument, calibration of the data as well as many example plots.

The file naming convention document, reference 2, describes the naming conventions for the Level 1A and 1B files. The software described in this document reads images from the L1A files. The MIMI L1a data file layout document, reference 3, covers the contents and structure of the L1A files. Knowledge of the structure of the L1A files is not necessary to run this software but the document lists the sensor file channel names and descriptions, which might be helpful in some cases.

For further assistance in working with the processing system, the C++ input and output code that the IDL code calls to read the L1A data and the software directory structure, refer to reference 4, the processing software guide. The processing guide has a detailed description of the scripts that set up the users environmental variables needed by the IDL software and propel the user into IDL. Currently, the software runs on the Linux and Mac systems using GNU make, C++, C, and IDL. The option to run entirely in IDL has been added to the software.

Reference 5 is the User Guide for all the IDL analysis software. Reference 6 is the User Guide for the IDL operations software.

 

Document Title

1.     J. Vandegriff, R. DiFabio, D. Hamilton, M. Kusterer, J. Manweiler, D. Mitchell, C. Paranicas, E. Roussos, Cassini/MIMI Instrument Data User Guide, February 8, 2013.

2.     M. Kusterer. Cassini/MIMI Data Analysis Center File Naming Convention, revision 10, May 22, 2014.

3.     M. Kusterer, L. Burke, Cassini/MIMI Data Analysis Center Level 1A File Layouts, revision 21, May 22, 2014.

4.     M. Kusterer. Cassini/MIMI Data Analysis Center Processing Software Guide, revision 10, January 17, 2014

5.     M. Kusterer, Cassini/MIMI Data Analysis Center IDL Analysis User Guide, revision 12, May 22, 2014

6.     M. Kusterer, Cassini/MIMI Data Analysis Center IDL Operations User Guide, revision 1, May 22, 2014

 

4.    Document Overview

This document describes the XINCA Skymap and Thumbnail software for the MIMI team. The interactive menu is called from the main MIMI menu. The XINCA menu code makes a command line call to the XINCA_NEWSKYMAP.PRO software to perform the plots. The multi-XINCA calls XINCA_MULTI3.PRO. This division of the menu code from the underlying plotting software allows the same command line programs to be called in a batch mode from the IDL menus, processing system and the web application menus.

The menu is called in a non-blocking mode so that the IDL command line is active during the menu operation. Compiled changes to the programs called by the menu during operation will be used in the next call.

For more information on using all the program parameters, see the program file headers where the parameters are explained in detail. The program names are shown in all caps since that was the IDL syntax at the time that this project was started and matches the syntax in the programs.

 

5.    How to Access MIMI Software

The MIMI IDL analysis software can be accessed by using the csh scripts in the /project/cassini/decomsoft/arch_`uname`/scripts directory on the Linux systems. These scripts set up environmental variables and then start up the IDL software. The `uname` Linux call will select the proper version based on the user’s platform type. Currently we support Linux (arch_Linux) and Mac (arch_Darwin). The Mac users would use the path set up for their systems.

In the processing software guide, listed in the previous related documents section, section 2.4.1 described how to set up the USER_DAC_DEFINES script which resides in the  /project/cassini/decomsoft/arch_`uname`/scripts directory. Only Mac users need to edit this file. All users do need to source this file before using the scripts to enter IDL described in this section.

source /project/cassini/decomsoft/arch_`uname`/scripts/USER_DAC_DEFINES

Most of the scripts to launch IDL take one parameter that is the software version to use. The parameter can be “dev” for development version, or “prod” for production version. The parameter is not required for all scripts and will default to use the production software. The main MIMI menu script is called as follows (the first defaults to production, the second explicitly uses production and the third uses the development version):

/project/cassini/decomsoft/arch_`uname`/scripts/mimi_menu

/project/cassini/decomsoft/arch_`uname`/scripts/mimi_menu prod

/project/cassini/decomsoft/arch_`uname`/scripts/mimi_menu dev

The scripts to launch into IDL or create the IDL save sets of routines are shown in the following table.

 

 

mimi_menu

The MIMI menu script brings up a menu that can access most of the IDL programs.  In each of the following sections, the script to access the program will be described as well as how to run the program from inside IDL at the command prompt. The scripts access the production software by setting the IDL_STARTUP environmental variable to point to the Decom_IDLstartup file. The startup file accesses the proper version of the IDL software, disk paths for the IDL code and sets up some display parameters for the PC displays. The script then runs the version of IDL that currently works with the MIMI software.

get_mimi_data

The get_mimi_data script brings up the MIMI data ASCII dump program menu.

get_mimi_images

The get_mimi_images script brings up the MIMI INCA image ASCII dump menu.

mimi_idl

The mimi_idl script just puts the user into IDL at the command prompt.

mimi_batch “command “

The mimi_batch script is used by the processing software to run the non-interactive IDL plotting from the Unix prompt. Put a non-interactive non-window producing IDL call inside the quotes.

mimi_makevm

The mimi_makevm script creates the IDL save set of the version of analysis software for use by the IDL virtual machine. The save set is placed in the vm_save subdirectory in the scripts directory.

./mimi_makevm would make the production version.

./mimi_makevm dev would make the development version.

mimi_runvm

The mimi_runvm script uses the IDL save set with the IDL virtual machine which does not require an IDL license

 

 

6.    MIMI Main Menu

A main menu has been designed to access many of the MIMI IDL graphics and data dumping programs. To access the main MIMI menu, the script is called from Linux or Unix as follows:

/project/cassini/decomsoft/arch_`uname`/scripts/mimi_menu

To access the main menu from inside IDL, type the following:

IDL>S = mimi()

 

Figure 1: MIMI main menu: The INCA Skymap/Thumbnails and INCA Multi Skymap/Thumbnails options are in the left most column.

 

 

The main menu shown in Figure 1, is divided into functional sections, analysis plotting, data output, external programs, analysis utilities, and information and operations programs. The XINCA Skymap/Thumbnails and XINCA Multi Skymap/Thumbnails programs are available in the Analysis Plotting program column.

At the bottom of the main menu are the following functions.

 

7.    XINCA Skymap and Thumbnail Programs

The Skymap is the input image projected onto the sphere of the sky, using the azimuthal projection with the 'north pole' of the sky sphere being the vertical axis, which is shown on the left in Figure 2. This display is designed for the analysis of ENA images, produced when the INCA high voltage ion and electron rejection plates are powered. This display is typically Saturn or Titan centered, in which case the vertical axis is aligned parallel with the body north pole. The skymap shown in Figure 2 uses the Saturn centered frame. Other frames keep the vertical axis in the projected image parallel with the spacecraft Z-axis. Various objects may be chosen for wire - frame overlay representation in the image display.

This menu also produces a (selectable) display known as Thumbnail, for with the INCA field-of-view (FOV) is represented in instrument, rectangular coordinates (vertical is elevation, parallel with the INCA slit and collimator plates, and with the Spacecraft Z-axis, horizontal is azimuth, perpendicular to the INCA slit and collimator plates). This display is the appropriate choice for displaying INCA ion measurements when the charged particle rejection plates are turned off. Error! Reference source not found. displays the INCA data using the thumbnail display. Using the on - board magnetic field vector (provided courtesy of the Cassini MAG Investigation) the contours of constant pitch angle may be used as overlays in the Thumbnail projections. When the spacecraft is rolling about its Z-axis, the coordinates of the Thumbnail map are the spin based coordinates to represent what a spinning imager 'sees'.

7.1    XINCA Skymap and Thumbnail

The INCA Skymap program plots the Skymap into a single window. If the time range includes multiple images, each will be read in and save and are available using the < and > arrows under the skymap. The image data can be projected and displayed into multiple coordinate systems.

The XINCA_NEWSKYMAP.PRO program creates the skymaps and thumbnails. See the header of the program for more information on calling it from the command line.

To access the xinca menu from Unix or Linux:

cd /project/cassini/decomsoft/arch_`uname`/scripts

./mimi_menu

and select the INCA SKYMAP button. Or the user can run the following script and command:

./mimi_idl

IDL>s=XINCA_NEWSKYMAP_MENU()

To access the program manually the calling sequence is

XINCA_NEWSKYMAP, 1999, 175, 2027, 1999, 175, 2200, resolution, species, tof

Figure 2 shows the XINCA main menu with the Type tab displayed.

Figure 2: INCA Skymap main menu with Data-Type tab shown on the left. The skymap on the right shows the following overlays; the Saturn body grid in white, and the Saturn body axis in the SZS frame in orange and the Titan orbit as a white dotted line. The data displayed is from Saturn at March 19, 2007 (day-of-year 078) and is averaged using the simple image averaging method over 8 images. It is displayed using the Saturn centered frame.

 

 

File Pull-down Options. These options are available at the top of the menu in Figure 2 by using the pull-down File, Edit, Debug, Update and Help buttons.

Plot to PNG, JPEG, PS, PDF

This option will bring up a file selection menu and prompt the user to enter an output file path and name. If the current parameters have not been plotted, the new read will be performed before the image is plotted. The output file formats include PNG, JPEG, GIF (Linux only), PS and PDF (Linux only). Select the Print Multiple button on the Profile/Movie Tab to output all images for the entire time range.  If multiple files are created, they will be numbered sequentially. The default is to only print the displayed image.

Plot to Movie-GIF, MPG

This option will bring up a file selection menu and prompt the user to enter a movie file path and name. If the current parameters have not been plotted, the new read will be performed before the image is plotted. The program will create PNG files sequentially numbered and will use the Unix program convert to create a movie with a delay of 50. This option works on Linux and possibly will work on the MAC if the convert program is installed.

See the Save PNGS options on the bottom of the Profile/Movie Tab to make the program save the output files. The output movie files are placed in the users home directory and are labeled starting with movie_*.png. The user can make a movie manually with the PNGs using any movie producing software.

Read PNG into IDL window

This option will read in a PNG saved from XINCA into the menu window.

Plot Cursor Profile Window to PNG, JPEG

This option will bring up the file selection menu and prompt the user to enter an output file path and name. The Cursor Profile plot is plotted to an output file format in PNG or JPEG.

Colorbar

Select color map in a pop-up menu.

Background

Select the background color of the plot, black or white in a pop-up menu.

Save Image to IDL SAV, ASCII

This option will bring up a file selection menu and prompt the user to enter an output file path and name. The image can be saved to an IDL saveset or an ASCII file. The program will tack on a _nnn right before the file extension and if the Print Multiple button on the Profile/Movie tab is selected, all images will be written out to files and numbered sequentially.

The format of the IDL saveset and ASCII file is included in Appendix 1. Saved XINCA Image Format For IDL Saveset or ASCII File

Save Cursor Profile to IDL SAV, ASCII

The option to save the cursor profile information will save the information shown in the text window to an IDL saveset or an ASCII file. The format depends on which cursor function is being used.

Save Profile Grid to IDL SAV, ASCII

The image values from the profile grid set up using the Profile/Movie Tab can be saved to an IDL saveset or an ASCII file.

Save Menu Values

The majority of the menu parameters used to plot the skymap or thumbnail can be saved to an IDL saveset. This option allows the user to save the complicated menu setup for a particular type of image and read it back in at another time.

Restore Menu Values

The XINCA program can read any saved IDL menu savesets and will set the menu options accordingly.

Edit Pull-down Options

Edit Pixel Map

The Edit Pixels option allows the user to turn off the image pixels. The menu to select the image size to edit is described in Figure 3 and Figure 4 shows the 16 x 16 image pixel map menu.

Debug Pull-down Options

Insert Test Image

This option overrides the image with a test image.

Set S/C Position to Saturn Z 15 Rs

This option loads a special SPK file in which the spacecraft is stationary and puts it with it’s Z-axis at 15 Saturn Radii.

Unset S/C Position

This option unloads a special SPK file in which the spacecraft is stationary and puts it with it’s Z-axis at 15 Saturn Radii.

Set INCA pointing to SZS-Z

This option loads a special SPK file in which the INCA boresight is the same as the SZS Z-axis.

Unset INCA pointing

This option unloads a special SPK file in which the INCA boresight is the same as the SZS Z-axis.

Update

This option calls the read and calibration routine for the image and displays the image in the skymap.

 

Description: pixel

Figure 3: INCA Pixel Edit Menu. The menu allows the user to select from the different INCA image sizes.

 

The edit pixel map option is found under the FILE button. Select the image size to match the image being viewed from the menu in Figure 3 and the pixel map menu in Figure 4 will appear.

 

Figure 4: 16 x 16 Pixel Map Menu. It is used to mask pixels in the image and the user selects the pixels to exclude. In any field, hit return to make the change. The remove corners fields removes N pixels from the nearest corner. The Remove Center Center removes N pixels from the center. The Remove Upper Center removes N pixels from the center of the top of the image. The Remove Lower Center removes N pixels from the center of the bottom of the image. The Remove Row removes pixels from the row ordered from the top = 0. The Remove Column removes pixels from the column left = 0.

 

Figure 5: The XINCA thumbnail shown in this figure is created by averaging 8 images together using the quick image averaging method. The pitch angle contours for 90, 60 and 30 degrees are displayed. The data displayed is from Saturn at March 19, 2007 (day-of-year 078). In the thumbnail option, the INCA field-of-view (FOV) is represented in instrument, rectangular coordinates (vertical is elevation, parallel with the INCA slit and collimator plates, and with the Spacecraft Z-axis, horizontal is azimuth, perpendicular to the INCA slit and collimator plates). The left side of the menu shows the options available on the Aves/Compton Getting tab menu options.

 

XINCA Time Options. These options are available at the top of the XINCA menu shown in Figure 5.

Time Selection Method

The time can be entered two ways. The user can select the Enter Time button and use the standard Start and Stop time fields. The user can also use the Enter File option to select a time file which contains multiple UTC time ranges in the following format:

2004-251T10:10, 2004-251T14:30

2004-252T10:10, 2004-252T19:00

2004-254T10:10, 2004-254T18:30

2004-256T06:00, 2004-256T11:15

The multiple time range format allows the user to skip periods of data easily. When this mode is selected, the Time Range becomes a pull-down display of the time ranges selected.

Start and Stop UTC

Year

Input 4-character year.

Doy

Input 3-character day of year that starts with 1.

Hour

Input 2-character hour with a range of 0 to 23.

Min

Input 2-character minute with a range of 0 to 59.

Sec

Input 2-character seconds with a range of 0 to 59.

 

 

XINCA Data-Type Menu Tab Inputs. These input are available on the XINCA menu in the Data Tab with the Type sub-tab selected as is shown in Figure 2.

Skymap or Thumbnail

The Skymap option is the input image for one image resolution, species, and time-of-flight (TOF) projected onto the sphere of the sky, using the azimuthal projection with the 'north pole' of the sky sphere being the vertical axis, which is shown on the left in Figure 2. This display is designed for the analysis of ENA images, produced when the INCA high voltage ion and electron rejection plates are powered.  Figure 2 displays the skymap using the Saturn centered frame.

In the thumbnail option, the INCA field-of-view (FOV) is represented in instrument, rectangular coordinates (vertical is elevation, parallel with the INCA slit and collimator plates, and with the Spacecraft Z-axis, horizontal is azimuth, perpendicular to the INCA slit and collimator plates). Error! Reference source not found. shows the INCA data in the thumbnail display.

Resolution (Res) and Species

The high spatial resolution images are produced in Hydrogen - - H+ low, H+ high, (where low and high refer to TOF - therefore "low" is higher in energy than "high". For Spatial H, "low" corresponds to 55keV to 90keV, "high" corresponds to 24keV to 55keV) or Oxygen - Ox low (170keV - 230keV), Ox high (90keV - 170 keV). The H+ high and both Ox images are at 32 x 32 pixel resolution over the 90 (azimuth) by 120 (elevation) INCA FOV. The H+ low are at 64 x 64 pixel resolution.

The high time resolution images do not discriminate between species, but are typically dominated by hydrogen. These images are at 32 x 32 pixel resolution over the 90 (azimuth) by 120 (elevation) INCA FOV. They are produced at 4 times higher cadence than the spatial and mTOF resolution images.

The high mTOF resolution images, 16 x 16 pixels covering the INCA FOV, are produced for both Hydrogen and Oxygen. They are each available at 8 energies for each species - for H, they are produced at 5 - 13keV (TOF7 or "high"), 13 - 24keV (TOF6), 24 - 35keV (TOF5), 35 - 55keV (TOF4), 55 - 90keV (TOF3), 90 - 149keV (TOF2), 149 - 227keV (TOF1), and 227 - 360keV (TOF0 or "low"). For oxygen the energies are 46 - 68keV, 68 - 90keV, 90 - 129keV, 129 - 168keV, 168 - 231keV, 231 - 332keV, 332 - 589keV, and 589 - 1000keV.

TOF       

High mass TOF images have low - high (0, 1, 2, 3, 4, 5, 6, 7) TOF options.

High Spatial and Time resolution images have low (0) and high TOF (7) only.

Units

The image data units are available in counts, counts/sec, integral flux or differential flux. The counts/second option delivers data in counts per second where the pixel counts are divided by the image accumulation time. The int flux option delivers the data in integral intensity and the units are counts/(cm-sr-s). The dif flux option delivers the data in differential intensity, counts/(cm-sr-s-keV).

Spin Mode

The image set can include those taken during instrument spin or stare mode or both.

Quad

When the instrument is in spin mode, the 4 images taken during a spin, if included in the time range, can be displayed side by side. This option hasn’t been tested well.

Rad, Lat, LT

Select the celestial body relative to which the spacecraft location coordinate values radius, latitude, local time (LT), L value and SKR Longitude are calculated.

SKR Longitude

The SKR longitude can be plotted in east or west longitude.

Exclude Cnts: Lo and Hi

Low - Select whether to exclude counts below a certain value

High - Select whether to exclude counts above a certain value

Frame

The desired reference frame in which the image is projected and sc_pos, spin_axis, and boresight vector are going to be returned in for the output of the IDL saveset. Some of the frame options are described below:

Boresight - The primary (X) axis is the CASSINI_MIMI_INCA boresight axis and is labeled X. The secondary (Z) axis is the Z axis of the IAU_SATURN frame (Saturn north spin axis vector). The Y-axis completes the right - handed system.

Saturn - This frame is a dynamically defined frame, defined as follows: the primary axis is the CASSINI spacecraft - to - Saturn vector and is labeled X. The secondary Z axis is the Z axis of the IAU_SATURN frame. The Y-axis completes the right - handed system.

Titan - This frame is a dynamically defined frame, defined as follows: the primary axis is the CASSINI spacecraft - to - Titan vector and is labeled X. The secondary Z axis is the Z axis of the IAU_TITAN frame. The Y-axis completes the right - handed system.

Saturn SZS - The primary axis, labeled Z, is parallel to the Saturn spin axis. The Y-axis is defined as the cross product of this vector with the Saturn - Sun vector. The X-axis completes the right - handed system and is directed "towards" the Sun.

SKR - Projected - This frame is a Saturn centered frame, similar to XINCA_SATURN_CENTERED, as the primary axis is defined as the spacecraft - Saturn vector. However, instead of utilizing the Saturn - sun vector as the definition of the proper clock angle about the primary axis, this frame uses the SKR prime meridian. By SKR, we refer to the currently available source for this information (SLS3, SLS4 south, etc.).

Projection Rs

This option is the width of half of the projected frame in Saturn Radii and is only used for the projected frames.

Projection Npts

This option is the resolution of the map projection window in pixels and is only used for the projected frames.

Projection Axis Color

This option is the color of the map projection axis.

Colorbar

This option turns on the display a colorbar for the image pixel values.

Titles

This option turns on the display of titles at the right of the image

Include Date

This option puts a date at the lower left corner of the image when it is plotted to an output file like the PNG or JPEG.

IDL Map Type

The image can be rendered into many of the IDL Map Types. The default map type is Azimuthal, but Cylindrical, Mercator, Hammer and Mollweide are available.

Charge

The INCA instrument is considered to be in ion mode when the voltage applied to the collimator is less than a threshold (1000 volts currently). When the collimator voltage is above that threshold, the instrument is considered to be in neutral mode. The data from just ion or neutral mode or both may be plotted.

Linear or Log

This option selects the color map scaling function, logarithmic or linear.

Min and Max

This option selects the values by which to scale the images. Leaving the minimum and maximum scaling limits at zero forces automatic color bar scaling for the entire array of images. The value is entered using the linear values even if in logarithmic mode.

Shift Theta and Phi

The shift theta and phi option is used to apply a known correction factor in units for the 64x64 image to the image. Currently the value recommended by the instrument team is :

Shift_pixel = [-1.5, 0.5] [Theta, Phi]

Overlay Time Width

The overlay time slider defines a time during the image accumulation time that is used to plot the body overlays. The accumulation time would be the summed accumulation times of all images if they are averaged or summed to get the image.

View Time Width

The view time slider defines a time during the image accumulation time that is used for the image frame when projecting the image into the selected frame. The accumulation time would be the summed accumulation times of all images if they are averaged or summed to get the image.

Image Time Width

The image time slider defines a time during the image accumulation time that is used for  the selected frame when projecting the image into the selected frame. The accumulation time would be the summed accumulation times of all images if they are averaged or summed to get the image.

Slider 50%

The button beside the 50% button will cause the Overlay and View Time Width sliders to track together.

The 50% button will cause all the Time Width sliders to change to 50%

Maintain Constant Radius

When a value other than 0 is entered in Rbody field, the image will be displayed with latitude and longitude limits that maintain a constant radius. The constant radius option will not be used if the radius is greater than 100 or the instrument is in spin mode.

Rbody – Number of body radii

Body – Celestial body to use.

 

 

XINCA Data-Skymap Tab Inputs. These inputs are available under the skymap image in Figure 2.

Image Advance Controls

The controls under the left side of the skymap are the image advance controls.

< - Displays the image with a start time before the one currently displayed.

> - Displays the image with a start time after the one currently displayed.

Total – Displays the total number of images in the time range

Curr – Index of the currently displayed image in the set.

Incr – How many images to skip when < and > are selected

Latitude and Longitude Controls

Latitude and Longitude limits set the portion of the sky and location in the selected frame to be viewed.

Maximum and Minimum

The maximum button will set the latitude and longitude to -80 to 80

The minimum button will set the latitude and longitude to -60 to 60

Flat Image Size

The flat image size button will set the latitude to [-60, 60] and longitude to [-45, 45]

Flat Quad Size

The flat quad size button will set the latitude to [-60, 60] and longitude to [-45, 315] if the view is a quadrant image

 

 

XINCA Data-Aves/Compton Tab Inputs. These inputs are available using the Data tab with the Ave/Compton sub-tab as is shown in Figure 5.

Data Source

The default data source is to use the L1a binary files. However, the option to use the PDS ASCII data files is available.

Sum and Ave

Select the number of images to sum or average (2 - >) and select the averaging or summing option. The default is 1, which means no summing or averaging.

Width

Select the STEP between the output averaged or summed images. The Default, 0, has the effect of stepping forward in time by the number of images chosen for the sum or average, so that each output image is independent and contiguous. Choosing values other than 0 forces that value to be used. For example, if the user is averaging over 10 images, leaving STEP at 0 means each successive group of 10 input images will be averaged into a successive output image. Choosing 10 will have exactly the same effect. However, choosing 1 will result in a "sliding boxcar" average, where 10 input images are averaged to form 1 output image, then the program moves forward by 1 image accumulation time and forms another 10 image average for the next output image. This second average will include nine of the images included in the first average, plus one additional image forward in time. This achieves a sort of morphed sequence of images with strong persistence from one image to the next in the sequence, suitable for creating movie image frames.

Smooth

Applies a boxcar smoothing function to the mapped image. The purpose is to smooth the visible image to aid the eye in interpreting the image as a 3D structure and not make the eye unconsciously map it to the sphere.

CAUTION!!: Localized features broaden. Care has to be taken when interpreting.

Edge

Turns on edge detection during smoothing. This leaves the edges of the INCA FOV un - smoothed, usually desirable since the algorithm is otherwise smoothing meaningful values inside the FOV with zeros outside.

# Sum and # Ave

The number to sum or average is the number of images to be combined. The value should be greater than one to take effect. Summing should only be used on counts.

Averaging Method Quick

The default image averaging method, quick, will stack the images on top of one another in stare mode, take the sum and apply the average if selected. If the instrument is in spin mode, then the quick averaging method will stack the matching sector images on top of one another to get the sum.

Averaging Method Simple

The simple image average method was created as a quicker and less accurate method than the motion average method discussed below, which is fairly slow. It is more accurate than the quick method discussed above.

The simple method takes the latitude and longitude of the pixel in the initial image frame and calculates the resultant value and location in the final output frame of reference. The resultant images in the output frame are summed and averaged if selected.

The wholesky field should be on for this method.

Averaging Method Motion

The motion average option is a C program that assigns the relevant value (sum, average, integral flux or differential flux) to each pixel in the output frame of reference. This is accomplished pixel by pixel and there are 4^(k-1) sample points computed for each pixel. For each image pixel sample point, the latitudes and longitudes in the original image frame are converted to the latitude and longitude of the output frame. Then the pixel of the final image that corresponds to this latitude and longitude is calculated. Finally, the relevant quantity is obtained from the original pixel based on the units selected. The next step is to combine all of the quantities from the sample points for the given image and the results are combined for the sum or average. It can take a long time but is very accurate.

This C program has been added to the SPICE icy library so is available in IDL. It does require the MOTION_STAT and MOTION_K parameters to be set.

The wholesky field should be on for this method.

Motion Averaging K

The k value determines the accuracy of the calculation. There are 4^(k - 1) sample points computed for each pixel. K must be <= 4. The default value of K is 2.

Motion Averaging Stat

The motion stat field sets the statistically significant counts value for a pixel to be included in the calculation. The default value for Stat is 0.

Whole Sky

The Simple and Motion averaging methods use the whole sky button to define how much of the sky is used during the calculation. Currently, the whole sky option must be on since the motion averaging method doesn’t work correctly without it.

Compton Getting

This option applies a correction for the Compton–Getting effect to the images. This option uses the Gamma and Wind speed parameters.

Compton Getting Gamma

Gamma: Compton-Getting Gamma parameter. It is usually close to 2.0 in the solar wind frame and that is the default value.

Compton Getting Wind Speed

Wind_speed: This is the convective speed of the plasma for the Compton-Getting correction. The default value is 500.

 

 

 

XINCA Data-Cursor Tab Inputs. These options are available from the Data tab in the Cursor sub-tab as is shown in Figure 6.

Turn on Cursor Window

The Turn on Cursor/Open Window button will open the additional cursor pop-up window that contains a text window at the top that echoes the data being plotted. At the bottom of the window is a plotting window. Selecting the button also turns on sensing for mouse movements in the skymap area. To eliminate the cursor pop-up window, the user should turn this option off.

Echo to Page

The Echo to Page option will write the information selected to the cursor pop-up window text portion.

Cursor Type

Skymap (cursor)

The skymap cursor draws X and Y in the map window coordinates. The text window will echo longitude, latitude and image values for the pixels that the cursor lines overlap. The plot window will contain two plots; longitude versus image value and latitude versus image value. Figure 6 shows the image cursor but the output for the skymap cursor would be similar, except the cursor would use the map window latitude and longitude instead of the image azimuth and elevation.

Image (cursor)

The image cursor draws X and Y using the image coordinates. The text window will echo azimuth, elevation and image values for the pixels that the cursor lines overlap. The plot window will contain two plots; azimuth versus image value and elevation versus image value. Figure 6 shows an example of the XINCA menu with image cursor results in the cursor window.

Exobase

The exobase cursor function works a little differently from the other cursors. It requires the user to display a set of body exobase lines. The exobase function is described in the XINCA Overlay Tab Inputs table. If the exobase line set is displayed, upon opening the cursor window, the pixel data overlaid by each exobase line is plotted in a line plot in the cursor pop-up window. Figure 7 shows the exobase overlay plotted on the skymap and the exobase line plots in the cursor pop-up window.

Radial (cursor)

The radial cursor requires the user to be in a body-centered frame of reference. The # spokes and # circles fields in the menu, the mouse cursor click location and the body centered frame determine where to draw the radial cursor circles and lines. The click position of the mouse determines the location of the outer most circle. The pixel data overlaid by each circle and line will be displayed in the cursor pop-up window line plot. Figure 8 shows the radial cursor on the skymap and the resulting line plots in the cursor pop-up window.

Grid

The cursor grid type requires the user to display the profile grid before use. Display of the profile grid is described in the XINCA Data-Profile/Movie Tab Menu. The cursor grid type allows the user to select two intersecting grid lines with the mouse and plot the image pixel values overlaid by the grid lines in line plots in the cursor pop-up window which is shown in Figure 9.

Spectrogram (cursor)

The Spectrogram cursor type allows the user to draw a circle on the skymap with the mouse. The cursor left button is held down, the mouse is moved and the button is released to draw the circle over the area of interest. The cursor pop-up window shows the text output at the top and below is shown the selected data in a spectrogram. The day, hour, min and sec fields at the bottom of the cursor tab menu, select the time range of the spectrogram and the values from the images of that same resolution, species and TOF with a start time in that time range will be included. The slider labeled spectrogram is used to select the spectrogram start time. The slider represents the spectrogram time range and increasing the slider value moves the start time for the spectrogram back in time. Figure 10 shows the spectrogram cursor circle on the skymap and the pop-up window with the spectrogram.

Spectrogram Mag Angle

The Spectrogram mag angle type allows the user to enter a mag angle in and out value. The pixels that have pitch angle within the angles of interest will contribute to the spectrogram. (To tell if the image has pixels within the range, try displaying the pitch angle contour on the image.) The cursor pop-up window shows the text output at the top and below is shown the selected data in a spectrogram. The day, hour, min and sec fields at the bottom of the cursor tab menu, select the time range of the spectrogram and the values from the images of that same resolution, species and TOF with a start time in that time range will be included. The slider labeled spectrogram is used to select the spectrogram start time. The slider represents the spectrogram time range and increasing the slider value moves the start time for the spectrogram back in time.

Spectrum  (cursor)

The Spectrum cursor type allows the user to draw a circle on the skymap with the mouse. The cursor left button is held down, the mouse is moved and the button is released to draw the circle over the area of interest. The cursor pop-up window shows the text output at the top and below is shown the selected data in a spectrum. The accumulation time of the displayed image determines the time range of the spectrum and the values from the images of that same resolution, species and TOF will be included.

Spectrum Mag Angle

The Spectrum mag angle type allows the user to enter a mag angle in and out value. The pixels that have pitch angle within the angles of interest will contribute to the spectrum.  (To tell if the image has pixels within the range, try displaying the pitch angle contour on the image.) The cursor pop-up window shows the text output at the top and below is shown the selected data in a spectrum. The accumulation time of the displayed image determines the time range of the spectrum and the values from the images of that same resolution, species and TOF will be included.

Spectrogram Radius

The Spectrogram Radius cursor type draws a line “radius from body in km” from “radius body” when the user clicks anywhere in the skymap. The “radius from body in km” and “radius body” fields are at the bottom of the Cursor tab menu. The pixel data included in the circle will be displayed in the cursor pop-up window as a spectrogram. The day, hour, min and sec fields at the bottom of the cursor tab menu, select the time range of the spectrogram and the values from the images of that same resolution, species and TOF with a start time in that time range will be included.

Spectrum Radius

The Spectrum Radius cursor type draws a line “radius from body in km” from “radius body” when the user clicks anywhere in the skymap. The “radius from body in km” and “radius body” fields are at the bottom of the Cursor tab menu. The pixel data included in the circle will be displayed in the cursor pop-up window spectrum. The accumulation time of the displayed image determines the time range of the spectrum and the values from the images of that same resolution, species and TOF will be included.

# Spokes

The # spokes fields determine the number of lines in the radial cursor.

# Circles

The # circles fields determine the number of circles in the radial cursor.

Mag Angle

The Mag Angle In and Out fields are used to determine the data

X-axis and

Y-axis Log/Linear

The scale mode for the X-axis (if not displaying time) and Y-axis are changed from logarithmic to linear using this parameter. If the X-axis is displaying time, it will ignore this setting.

X-axis and Y-axis Min and Max

The X-axis (if not displaying time) and Y-axis limits are set using these parameters. When the minimum and maximum values are both 0, the data is plotted using the data minimum and maximum. If the X-axis is displaying time, it will ignore this setting.

Colormap Log/Linear

The spectrograms use this parameter to set the scale mode of the Z-axis or color scale from logarithmic to linear.

Colormap Min Max

The Z-axis scale limits for the spectrograms are set using the minimum and maximum values if not both set to zero.

Spectrogram Image Location

This slider location slides the start time for the spectrogram backwards in time. The width of the slider equals the width selected in the spectrogram time length in the Day, Hour, Min, Sec time fields.

Radius from Body

This parameter is used by the Spectrogram and Spectrum Radius cursors. It controls the distance from the center of the Radius body that the cursor will be drawn.

Radius Body

This parameter is used by the Spectrogram and Spectrum Radius cursors. It controls the body that the cursor will be centered at.

Spectrogram Time Length

The spectrogram time length in the Day, Hour, Min, Sec time fields control the length of the time range for the spectrogram and the spectrum.

 

Figure 6: The XINCA Data-Cursor tab menu. This menu allows the user to select the cursor type and it’s parameters. The skymap shows the image cursor and the cursor pop-up window shows the text output and plot of the image pixel values across the image azimuth and elevation lines. The data displayed is from Titan from April 16, 2005 (day-of-year 106), and is displayed using the Boresight frame.

 

Figure 7: XINCA Data-Cursor tab menu showing the Exobase overlay at Saturn. The Exobase cursor function works a little differently from the other cursors. The exobase cursor option requires the user to display an exobase for a celestial body, using the overlays tab option. Clicking the mouse button in the skymap area will display the closest image pixel values to the points in each exobase line in the cursor pop-up window line plot. The skymap data displayed is from Saturn at March 19, 2007 (day-of-year 078) and is averaged using the simple method over 8 images. It is displayed using the Saturn centered frame.

 

Figure 8: XINCA Data-Cursor tab menu with radial cursor on the skymap. The # spokes and # circles fields in the menu, the cursor click location and the body centered frame determine where to draw the radial cursor circles and lines. The click position of the mouse determines the location of the outer most circle. The closest image pixel values to the points of each circle and line will be displayed in the cursor pop-up window line plot.

 

Figure 9: XINCA Data-Profile/Movie tab menu with the Titan Profile Grid. The cursor grid type allows the user to select two intersecting grid lines from the grid. The plots in the cursor pop-up window display line plots for the closest image pixel values to the points in the grid lines.

 

Figure 10: The Spectrogram cursor output (a circle) is shown in the skymap. The cursor button is held down, the cursor is moved and the button released to draw the circle over the area of interest. The cursor pop-up window shows the text output at the top and below is shown a spectrogram made from the points from the area of interest in each image over the time range selected. The day, hour, min and sec fields at the bottom of the cursor tab menu, select the time range of the spectrogram.

 

XINCA Data-Profile/Movie Tab Inputs. This tab menu is shown in Figure 9.

Profile Grid

The grid will be centered at the center of the frame of reference with the Z-axis of the grid parallel to the body spin axis and the settings below determine the number of horizontal and vertical lines and the step between. Figure 9 shows the Titan Profile Grid drawn using the Titan centered frame. The profile grid is drawn when the Update button is selected.

Profile Limits

The horizontal and vertical limits in radii to the selected body, can be entered as minimum and maximum [min,max] or one value [n] to use for both sides of the grid as is shown in Figure 9.

Profile Step

The step size between the lines is in radii to the selected body.

Profile Body

The profile body is used to determine the radii in-between the grid lines and the Z-axis used for the grid.

Print Multiple

When the time range includes multiple images the default operation is to only save the current skymap or thumbnail to an output format like PNG. Selection of the Print Multiple button will save all images included in the time range to output files that are labeled sequentially. This also applies to IDL savesets and ASCII files.

Low Res

Selection of the Low Res (resolution) button uses a lower resolution map window. Map window resolution determines the display time for the image.

Delay

Full movie production is only available on Linux systems. The delay parameter is the separation in time between the still images used to make the movie.

Movie-Save PNGS

This option saves the numerically indexed PNG files which are typically deleted after the movie option is finished. The user can save the PNG files to use with another movie software package.

 

 

XINCA Overlays Tab Inputs. The overlays menu is shown in Figure 11.

Pitch Angle Contours

The pitch angle contour(s) can be entered in the field as numbers separated by commas or ranges like 30-35. The default is [0, 30, 60, 90, 120, 150, 180]

Image Contours

The image contour option draws a line contour on the image itself. Values below the minimum and above the maximum linear values are ignored.

Image Grid

The image grid will plot a grid of the INCA FOV native coordinates (elevation/azimuth) over the image FOV.

Map Grid

The map grid will plot a grid of the displayed map coordinates (latitude/longitude) over the map.

Image FOV

The FOV option will only plot a perimeter frame showing the image FOV over the image.

Logo

If set then turns on APL logo with text.

Grid for Frame

The grid for frame will plot a grid in the frame selected in the pull-down menu below the button.

Square

Enable a square format window with minimum space for annotation. The effect of this keyword is essentially to put the colorbar in the right side (vertically) and annotation above and under the colorbar.

Planet Axis Multiplier

Moon Axis Multiplier

Sometimes the default length of the planet and moon axis selection is not acceptable depending on the size of the plot. Enter a new value and selection update to re-plot the data.

Body Time Width

The width is used when multiple body overlays are plotted. It will trigger the overlays to plot multiple times during the image accumulation time. This is useful when the scene geometry is changing quickly over the time span of the average.

Center

The center option will plot a single point at the center of a body.

Grid

This plots a latitude/longitude grid the size of the body radius at the position of the body. Not useful when far from the body.

Limb

The limb option plots the limb of the selected body.

Terminator

The terminator option plots the terminator of the selected body.

Title

The title is the two first letters of the body name plotted slightly offset from the center of the body.

Exobase button and limits

To display Exobase rings about the body, turn on the option and enter a low and high limit in kilometers and the number of exobase rings desired for the body. Figure 7 shows the exobase displayed on the skymap.

Axis

Axis Frame - This option draws the X,Y,Z axis in one or more of the following frames:

    SSO Saturn Solar Orbit. In this coordinate system, the Sun's position and the 90 - degree Sun angle is fixed. The Sun is always at the (0.0,0.0) position.

        X-axis points from Saturn to Sun

        Y-axis Z x X

        Z-axis is the Saturn orbital velocity x X

    SZS Saturn Equatorial System.

        Z-axis is parallel with Saturn spin axis

        Y-axis = Z-axis crossed with the Saturn to Sun Line

        X-axis = Y x Z (sunward)

    IAU Saturn Body Fixed frame based on IAU rotation model

        X-axis is where the prime meridian crosses the equator

        Y-axis Z x X

        Z-axis the body rotation axis

    Saturn Variable Kilometric Radiation Frame - South and North.

    Saturn appears to have a different rotational period for the northern and southern hemispheres, and the following two frames, SKR South and SKR North attempt to capture these rotating frames.

 

    Each frame has +Z as the spin axis of saturn (+Z in the IAU_SATURN frame, and also +Z in the SZS frame) and is offset from the IAU_SATURN frame by a rotation about the Z axis. But note that this rotational offset changes with time, and since it coveres such a long time period, it is not practical to describe the offset as a single polynomial. So we put the offset into a C-Kernel. These frame definitions are specified by the plasma wave team (RPWS) and are meant to characterize the variable rotoation rate of Saturn. These frames are only defined over a limited period of time.

    CASSINI_SKR_SLS4_SOUTH: 2004-256T00:00:00.000 - 2010-314T23:59:59.997

    CASSINI_SKR_SLS4_NORTH: 2006-095T00:00:00.004 - 2009-258T23:59:59.997

    SKR_SLS3: 2004-001T00:00:00.000 - 2007-222T23:59:59.999

    SKR_SLS2: 2004-001T00:00:00.000 - 2006-240T23:59:59.999

    The Saturn Moon System (SZM) frame is a dynamically defined frame. whose

        Z-axis is the Saturn spin axis.

        Y-axis of this frame is chosen to be the cross product of the Saturn - ReferenceMoon vector and this Z-axis.

        X-axis completes the right - handed frame.

Saturn Rings

Either all of Saturn’s rings or the individual rings can be displayed.

 

 

 

Figure 11: The XINCA Overlays tab menu displays the celestial body overlay plotting functions on the bottom and the other overlay plotting functions at the top of the menu.

 

7.2    Multi-XINCA Skymap and Thumbnail

The multi-XINCA Skymap and Thumbnail program allows the user to select a time range and plot multiple image species and TOF combinations over time. Only one image resolution type may be displayed at a time but multiple species and TOF image combinations can be displayed together on a page.

This section will show examples of the multiple skymap and thumbnail output as well as the multi-XINCA menu options that have not been already described.

The XINCA_MUTLI3.PRO program creates the skymaps and thumbnails in the multiple image formats. See the header of the program for more information on calling it from the command line. The MAKE_MULTI_PRODUCT2.PRO and MAKE_MULTIFLAT_PRODUCT.PRO contain examples calling the XINCA_MULTI3 program to create the image browse products.

 

To access the xinca_multi menu from Unix or Linux:

cd /project/cassini/decomsoft/arch_`uname`/scripts

./mimi_menu

and select the INCA Multi Skymap button as is shown in Figure 1. Or the user can run the following script and command:

./mimi_idl

IDL>s=XINCA_MULTI_MENU()

Figure 12: Multi-XINCA Menu with Type Tab. The selection of image species and TOF shown in the menu to the left, will result in the image show to the right. The top row displays hydrogen 55-90 keV images, the second row displays hydrogen 24-55 keV images and the bottom row displays oxygen 90-179 keV images and all are high spatial resolution images. The data is from a Titan flyby on April 16, 2005 (day-of-year 106). The Titan grid is shown in white and the Titan axis frame in the SZS frame is shown in orange.

 

The calling sequence for the program,

XINCA_MULTI_SKYMAP, 1999, 175, 2027, 1999, 175, 2200, resolution, species, tof

 

Multi-XINCA Specific Menu Parameters. Only the parameters that do not appear in the XINCA single format menu will be described here. Figure 12 shows the multiple-XINCA menu Type tab.

Type Tab Menu

Load Browse Product Parameters

After the user selects the skymap or thumbnail image type, this button will load the menu parameters that are used to create the skymap or thumbnail browse products. The skymap browse product is show in Figure 14 and the thumbnail browse product is shown in Figure 15.

Columns

The number of columns of images per page. The number of species and TOF combinations determine the number of rows. The time range selects the number images that will be filled in on one page in each column. If there are more images than the number of columns, only one window will be produced unless the Print Multiple button on the Scale/Compton/Movie tab is selected.

Hydrogen

The hydrogen TOF buttons select the hydrogen species TOF for high spatial and mTOF image resolution types, and the “all” species TOF for the high time resolution image type.

Oxygen

The oxygen TOF buttons select the oxygen species TOF for high spatial and mTOF image resolution types.

Flip Thumbnail Images

The thumbnail images are automatically flipped to align the sides correctly together if the instrument is in spin mode. This parameter may be used to flip the images manually. A gray bar is plotted at the bottom of the image if it has been flipped.

Maintain Constant Radius (Rbody)

This parameter allows the user to set a constant radius in Radii (body) from a selected body for all the images. If the distance of the spacecraft to the body is greater than 100 Radii (body) or the instrument is in spin mode, then this function will not be used. The skymap browse products use a value of 99 Rs (with a body=Saturn). When the value 99 is used, if the spacecraft to Saturn distance is greater or equal to 35 Rs then a value of 28 Rs is used. If the spacecraft to Saturn distance less than 35 Rs then the value of 25 Rs is used.

Scale/Compton/Movie Tab Menu. This menu is shown in Figure 13.

Auto-Scale Each

The images can be individually auto-scaled using this function. Each image will have a tiny colorbar at the side with the minimum and maximum scale value.

Auto-Scale Spec/TOF  

The default auto-scale selection is to scale like species and TOF image combinations together. The entire set of images in the time range selected will be used to generate the limits. This option will change the individual scaling for species/TOF combinations options.

Auto-Scale Together

All species and TOF image combinations can be auto-scaled all together. The entire set of images in the time range selected will be used to generate the limits. This option will change the individual scaling for species/TOF combinations options.

Individual Scaling for Species/TOF Combinations

The user can enter a minimum and maximum linear value limit range for each species and TOF image combination.

 

Figure 13: Multi-XINCA Scale/Compton Getting/Movie Tab Menu. The images displayed are high spatial resolution, hydrogen 55-90 and 24-55 keV images of a Titan fly-by on April 16, 2005 (day-of-year 106). The Titan center grid in white and axis in the SZS frame in orange are shown. The correction for the Compton–Getting effect has been applied using the default parameter values of gamma = 2, wind speed = 500 kl/sec. The Print Multiple button has been selected so multiple windows will be created as needed to display all images defined by the number of columns and the time range.

 

Figure 14: Multi-XINCA Skymap Browse Product. The data displayed is from October 26, 2005, day-of-year 299.

 

Figure 14 displays the skymap browse product. It displays the images in three rows by N columns of panels, where the bottom three rows are a continuation in time of the top three rows. Each row contains spin averaged high spatial energetic neutral atom (ENA) image skymaps (each one accumulated over four sectors), displayed for one species and time-of-flight (TOF) combinations from the INCA sensor of the MIMI instrument on the Cassini spacecraft.

Row one contains the high TOF Hydrogen images, row two contains the low TOF Hydrogen images and row three contains the low TOF Oxygen images. The high TOF oxygen in the spatial products usually has too little intensity to produce a good image, so we left it out of the browse products to allow more image space on the page images that are more useful. The energy range for each TOF range is shown to the right of each row. ENA images are collected when a high voltage is present on the INCA collimator. 

The value displayed is the log of the image intensity that is counts/(centimeters squared*steradian*seconds*keV). The color bars for each row are independent and are determined by the minimum and maximum pixels in that row (i.e., for the entire time range selected). Each original image was 64 x 64 pixels and was transformed into the following frame. The skymap frame is a dynamically defined frame, defined as follows. The primary axis X is the INCA boresight axis. The secondary Z-axis is the Z-axis of the IAU_SATURN frame. The Y-axis completes the right-handed system. The skymap display is defined to display every frame with the Z-axis up, X-axis into the page and Y axis out to the left. So in the skymap, using this frame, Z or up is the spin axis of Saturn, into the page is the boresight.

  

Scaling has been applied to the image to normalize the apparent size of Saturn, if;

   1. Saturn is in the field-of-view.

   2. The distance to Saturn is less than 100 Saturn radii.

   3. The spacecraft is not spinning.

In periods where the spacecraft is going in and out of Z-axis spin mode, the images will appear un-zoomed and zoomed (non spin mode).

If they are visible in the image, the orbit of Titan (dotted line), Titan center (dot), and the axis for Saturn equatorial system frame (centered at Saturn) are displayed. The definition of the Saturn equatorial system frame is the primary axis, labeled Z, is parallel to the Saturn spin axis.  The Y-axis is then defined as the cross product of this vector with the Saturn-Sun vector.  The X-axis completes the right-handed system and is directed towards the Sun.

At the top of the page, the Rs=radius to Saturn, Lat=latitude in IAU_SATURN frame, LT=Saturn Local Time, L=L value, local time of Cassini relative to Saturn, Lon skr-wl= Longitude of Cassini in the Saturn Kilometric Radiation (western longitude) frame. These measurements are calculated at the start time of the first image.

 

Figure 15: Multi-XINCA Thumbnail Browse Product. The data displayed is from October 9, 2013, day-of-year 282.

 

Figure 15 displays the images in 1 to 10 columns of high time-of-flight (TOF) browse ion thumbnail images displayed for seven time-of-flight ranges (rows) from INCA. Ion images are collected when no voltage is present on the INCA collimator.

The image species include hydrogen at TOF ranges, where the energy range for each TOF range is shown to the right of each row. The value displayed is the log of the image intensity that is /(centimeters squared*steradian*seconds*keV). The color bars for each row are independent and are determined by the minimum and maximum pixels in that row (i.e., for the entire day). 

The definition of the thumbnail frame is the primary axis X is the INCA boresight axis that goes into the page.  The secondary axis is the Z-axis of Cassini. The Y-axis completes the left-handed system. The elevation of the image goes from -60 degrees at the bottom to 60 degrees at the top of the image. The azimuth of the image goes from -45 degrees on the left to 45 degrees on the right.

Each original image was 16 x 16 pixels and was expanded to 60 x 80 pixels in the PNG file. The pitch angle of INCA is displayed on top of the image as contours for the following degrees [0,30,60,90,120,150,180] in the B-field particle flow.

At the top of the page, the Rsaturn=radius to Saturn, Lat=latitude in IAU_SATURN frame, LT=Saturn Local Time, L=L value, local time of Cassini relative to Saturn, Lon skr-wl= Longitude of Cassini in the Saturn Kilometric Radiation (western longitude) frame. These measurements are calculated at the start time of the first image. 

The seven TOF range (each one accumulated over four sectors), four sector images are displayed one above each other for the same time. The highest TOF (TOF id 0) is not a well-behaved so it was not included in the browse product. The channel is sensitive to background, electrons, and has variable sensitivity to ions in that energy range (greater sensitivity at the edges, highly spectral slope dependent, not calibratable). Time increases from left to right.

Images, taken when Cassini is spinning about the Z-axis, may be flipped horizontally depending on the spin direction. This is so that contiguous images line up properly. All images in a column are flipped or not flipped and flipped images are indicated by a grey bar at the bottom.

 

Figure 16: Multi-XINCA One Resolution, TOF Species Time Series. The data displayed is from April 16, 2005, day-of-year 106 which was a Titan flyby. The Titan grid is displayed in white and the SZS axis is displayed in orange.

 

Figure 16 shows the option to display one species, TOF image combination, hydrogen 24-55 keV, over a long period of time. Each row shows the images following in time from the previous row. This period was a Titan flyby and the white grid for Titan and orange Titan axis is shown for the SZS frame. The color bar range uses the auto-scale for one species/TOF combination. For the one species/TOF combination, all images in the start and stop time range are used to calculate the minimum and maximum range. If the show multiple page option is used, all pages will display the same color bar range.

 

8.    Appendix

8.1    Saved XINCA Image Format For IDL Saveset or ASCII File

The IDL saveset will contain the following parameters for Saturn (when viewing other bodies slightly different sets will be saved):

Parameter

Type Field

Description

frame

string 

Frame of reference used to display the image in the skymap.

image

double array[imagesize, imagesize]

The original image in the image FOV coordinates with image size equaling the native image pixel size.

imagedata

double array[1, 25]

An array of the data and image header values. Use the indexes in data_hdr_h.pro and image_hdr_h.pro to navigate.

image_datachar_scet

string

The start of the image accumulation in UTC yyyy-doyThh:mm:ss.msc

image_spinchar_scet

string

The start of the spacecraft spin containing that image in UTC yyyy-doyThh:mm:ss.msc

image_stop_datachar_scet

string

The end of the image accumulation in UTC yyyy-doyThh:mm:ss.msc

labels

string array[27]

An string array of the data and image header labels. The first 2 indexes contain the labels for the image_datachar_scet and image_spinchar_scet parameters. So [2] corresponds with imagedata[0,0], and [3] corresponds with imagedata[0,1] etc.

latitude

double 

The latitude in degrees at the start of the image accumulation.

latmax

float 

The maximum latitude of the edge of the map.

latmin

float

The minimum latitude of the edge of the map.

localtime

string

The local time of the Cassini spacecraft relative to body at the start of the image accumulation.

lonmax

float

The maximum longitude of the edge of the map.

lonmin

float

The minimum longitude of the edge of the map.

lvalue

double

The L value is calculated at the start of the image accumulation.

newimage

double [356, 400]

The skymap selection will save the image for one resolution type, species, and time-of-flight (TOF) projected onto the sphere of the sky and transformed into the user selected frame of reference.

The thumbnail selection will save the INCA field-of-view (FOV) which is represented in instrument, rectangular coordinates.

orientate

string 

Orientate is a string describing the new image array. For example,

Orientation newimage[0,0]=az -60,el -60 , newimage[0,max]=az -60,el 60, newimge[max,0]=az 60,el 60, newimage[max,max]=az 60,el 60

planet

string   

String name of planet

prime_meridian_frame

double array[3]

X-axis [1,0,0] transformed into the INCA_LL frame

prime_meridian_szs

double array[3]

X-axis [1,0,0] transformed into the SZS frame.

prjfrm  struct  = structure 

 

structure

{on:1,

centerbody:'' (planet/moon spice name),

planewidth: (in radius of centerbody),

planedensity: (npts on a plane side),

frame:frame}            

rs

double

Radius to Body in Body radius units

rss

double

Radius to Saturn in Saturn radius units

sc_pos_frame_kl

double array[3]

The spacecraft position in selected frame in kilometers

sc_pos_frame_rb

double array[3]

The spacecraft position in selected frame in radius to body

sc_pos_szs_kl

double array[3]

The spacecraft position in the SZS frame in kilometers

sc_pos_szs_rb

double array[3]

The spacecraft position in the SZS frame in radius to body

skr_lon

double

The Longitude in Saturn_Kilometric_rad frame is calculated at the start of the image accumulation.

spin_axis_frame

double array[3]

Z-axis [1,0,0] transformed into the selected frame.

spin_axis_szs

double array[3]

Z-axis [1,0,0] transformed into the SZS frame.

titan_pos_frame_kl

double array[3]

Titan’s position in the selected frame in kilometers

titan_pos_frame_rb

double array[3]

Titan’s position in the selected frame in radius to body

titan_pos_szs_kl

Double array[3]

Titan’s position in the SZS frame in kilometers

titan_pos_szs_rb

double array[3]

Titan’s position in the SZS frame in radius to body

totaltime

double

The total time in seconds that the image has been accumulated over

 

The ASCII file will contain the following header lines; image date in a string, the start and stop time, titles followed by values for the radius to body, latitude and LT, L value, and longitude in the SKR frame. The next lines are energy, units, spin stare mode, spin start time label and image time label followed by the UTC values.

The image data or the newimage array in the IDL saveset, starts with the number i or theta in [i, j], then the number of j or phi in [i, j] Each image is laid out in the following order with respect to theta and phi. The image size is based on the resolution of the map window.

Row 0, [0, 0:n]: covers phi from - 45o to + 45o at a theta of –60o

Row 1, [1, 0:n]: covers phi from - 45o to +45o at a theta of –58.2o

Row 2, [2, 0:n]: …

Row N, [n, 0:n]: covers phi from - 45o to +45o at a theta of +60 o