How to convert LASCO/SECCHI FITS to GIF

Karl Battams wrote about transforming the LASCO FITS to GIF in 2006 January (Jan 31,2006 -- Pretty pictures for everybody... ). It's now at the bottom of this page. In short you have to remove the background and rescale an image to make it look good. How the backgrounds are generated is explained in the textfiles of the directories carrying the LASCO backgrounds. Details of the transformation from FITS to GIF can be found in the output of the LASCO Movie Machine.

Until now (2007 January 13) there are no background images for the STEREO/SECCHI images. So you have to make them by yourselve. I have found a program that does this rather easily. It's FITSWORK by Jens Dierks (Germany, with a german language user interface) for Windows. You can download it here (789 KB).

Start the program and go to 'Datei - Masterdark/-flat erstellen'. A window opens which looks like this (select Flats):

In the upper left corner you see the directories of your hard drive(s). In the lower left corner you have to select the files, which will be used to create the background image. Drag and drop them to to listbox at right and select Median (this will remove the stars, if the images are selected far enough). Click on 'Erstellen'. The file Masterflat.fit will contain the background image.

The five files in the listbox at right are the five files, which I have used to create the background file for the hi1a mcnaught image. I have had them already on my hard drive(s) and so I used them. The result was good (showing a very long streamer - extending almost 14 degrees from the Sun!) so I left it as it was.
But this was a bit of luck. I should have checked if these images have the same exposure time, same filter and same roll angle (at least). I did that afterwards and found exptime=24 seconds, filter=none for all five images, but roll angle (CROTA in the fits header) varying from -29.9 to -29.3 degrees. Obviously this change in roll angle didn't do much harm.

If you have a good background image you can proceed to remove the background with opening the masterflat.fit ('Datei - offnen) and then opening 20070109_060100_s4h1A.fts (this should be the active window) and then go to 'Bearbeiten - (Hell-)Bild dividieren'. A new window appears with title 20070109_060100_s4h1A_2.fts. This is the image with the removed background. You can now play with the histogram to make it look good.
Or save it and use another program to make it look good.

Rainer Kracht, 2007 January 13