IMAP - An IPAC Tool for PHT32 Data Reduction

The  IMAP (IPAC MAP package, is a visual and interactive tool that allows the user to inspect, clean, and perform empirical corrections for a number of instrumental effects (e.g., vignetting, long-term drift, flatfield) on the PHT32 observation data.  Bright sources (or "negative dips") in the map can also be masked out temporarily for improved fits of these instrumental effects in the data.  The IMAP takes a SPD level data from the PIA (ISOPHOT Interactive Analysispackage) and generates a new one with its corrections applied.  There are two ways to access this tool.  It is implemented into the PIA, so that you can run it by selecting the appropriate option, "Launch IMAP P32 processing" on the pull-down menu for the "Process" button on the PIA SPD Data Display window.  The other option is to run it outside the PIA, but this requires you to save the SPD data into a file and feed the output back into the PIA for the final map construction.

Using the

To use the IMAP implemented into the PIA, all you need to do is to click on the option, "Launch IMAP P32 processing" on the pull-down menu for the "Process" button on the PIA SPD Date Display window and follow instructions at the prompt.  Otherwise, you need to follow the steps outlined below when using the in a separate IDL session.

1. PIA --> SPD level

The P32 data needs to be saved by the PIA as an internal SPD file at the SPD level .   This file ends with ".ISPD".
2. Feed the SPD result into IMAP
Start an IDL session from the directory which contains the file and the saved SPD file.  Then type the following at the IDL prompt.  You should have saved to a file in advance.
IDL> .r
IDL> imap,'filename'
Then follow the comments and questions at the IDL prompt.

The displays several images at appropriate times to aid the user visually.  In addition, five of these displays, one from each of the major sections of program, are saved to file, so that the user can produce hardcopies easily.

In the end, the user has the option of saving the results to a new internal SPD file or exit without saving any changes.  The new file has ".ISPD_IMAP" ending to distinguish it from the original PIA result.

3. PIA --> Astrophysical Work --> map construction
Now you can load this new file into the PIA and construct the map as usual.  Please note that to read this file into the PIA properly, you need to delete the _IMAP ending.  Refer to the PIA User Manual for questions regarding the map construction.  Also, you should disable the Flat Fielding with the PIA mapping because IMAP already applied skyflattening.


The following is the description of each step of the IMAP program.  The green and blue capital letters are used to represent the program labels and to clearly show where the program moves to next.  The DISPLAY signals a new IDL window display and gives the description of what gets depicted visually.  Click on the DISPLAY to view an example.


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The pixel arrangement for the C200 detector is as follows.
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If you have any questions or comments, please do not hesitate to contact us.
Nanyao Y. Lu
(626) 397-9505

Min Y. Hur
(626) 397-7045

Mail Stop 100-22
770 S. Wilson Avenue
Pasadena, CA 91125
Fax : (626) 397-7018

Last update : April 2000