Re: Changes in the .fits header...

Posted by karenacollins on May 24, 2017; 9:50pm
URL: http://astroimagej.170.s1.nabble.com/Changes-in-the-fits-header-tp683p684.html

Hi Bill,

When images are combined in AIJ, the header is not currently automatically copied forward as you have found (because it is an underlying ImageJ code that is doing the work and it is FITS header unaware). I hope to have time to fix that in the near future. For now though, you can manually copy a FITS header from one image to another (i.e. after you median combine), by using AIJ_Toolbar->Plugins->Astronomy->'Copy FITS Header'. If the header has WCS (i.e. plate solve information), you will need to click the auto-contrast icon () above the new image so that the new WCS solution is recognized.

For more info about FITS header updates, see Appendix A.7 in the AIJ paper expanded version ( https://arxiv.org/abs/1701.04817 ), but I'll give an overview here:

If you don't want to change the fits header, disable both 'General' and 'Plate Solve' options in the 'FITS Header Updates' sub-panel. If you do want to update the headers, enable "General" and then click this icon in the same sub-panel to define what you want to update. If you are updating the FITS headers, you need to define your observatory location and target RA and DEC. That is done by pressing the DP Coordinate Converter icon and entering that information on the DP Coordinate Converter panel as shown below. The time for each observation is extracted from the FITS headers.

Alternatively, DP can automatically extract the RA, DEC, Lat, and Long info from the image headers, if available, by selecting the 'Target Coordinate Source' and 'Observatory Location Source' in the "FITS Header Updates" panel as shown here:

For this mode to work, you also need to specify the proper FITS header keywords that appear in your image headers in the "General FITS Header Settings" as shown below. That is the same panel as mentioned above which can be accessed by clicking the icon.



Hope that helps clarify things a bit,
Karen