3.3.4 HXT_ IMG (McTiernan) [*]

Jim McTiernan converted the FORTRAN program which was running on the mainframes to IDL. Currently the criteria used by HXT_IMG to stop the iterations is different from the FORTRAN program. HXT_IMG generally does not iterate as far. It takes a very long time to create a single image (between 1 and 30 minutes depending on the intensity) so we recommend running in batch mode when creating more than a couple of images.

1. The HDA data must be read into the variables data and index. A common way to do this is to use YODAT.
2. Now start running HXT_IMG by typing
   IDL> .run hxt_img
   
3. Answer `No' to the first question (``Have the image synthesis parameters been loaded and modulation patterns been calculated?'')
4. Now comes the hard part. It is necessary to know the coordinates of the flare in HXT units (126 arcsec units). Please see the routine HXT_IMG_POS to see how to determine the HXT coordinates. For example, the 15-Nov-91 flare the coordinates were (, )
5. Answer `Yes' to the next two questions (use the default parameter files)
6. Select the channel you wish to have an image synthesized for
7. Answer `YES' for background subtracted
8. Locate a portion of the light curve where the signal is low (just background). Click with the left button on the plot at the start time, click with the right button at the end time, click the middle button to select the portion you have marked.
9. Locate a portion of the light curve where the signal is high where you want to have the HXT image synthesized. Click with the left button on the plot at the start time, click with the right button at the end time, click the middle button to select the portion you have marked.
10. The generation of that image will begin.
11. You will be asked if you want to save the results in an output file. That output HXI file can be read with YODAT or directly with RD_HXI.
12. When it is finished, the variables index_out and data_out will hold the results.