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Re: .fz File Will Not Open

Posted by karenacollins on Sep 15, 2021; 8:22am
URL: http://astroimagej.170.s1.nabble.com/fz-File-Will-Not-Open-tp1603p1608.html

Hi Rick,

There are multiple possible sources of the problem. The first is that the ra/dec reference location is given at pixel 13422.2, 6306.333 (CRPIX1, CRPIX2). That location should correspond to RA=208.7410277581, Dec = -16.33504840526 (CRVAL1, CRVAL2), which is similar to the coordinates you provided below. However, the image that opens for me is 2046 x 4094, so the reference location would be off of the image. I'm not sure if this is an inconsistency caused by the multiple HDUs, or if it is intended to be that way. Another potential issue is that the TPV projection is being used in the WCS headers. Unfortunately, AIJ does not currently support that projection type (there's an unobvious note about that in the white information line below the image display menus). I've re-plate-solved the image using astrometry.net, which uses coordinates AIJ has been well tested against and get roughly RA = 13:53:40, Dec = 15:25:40 near the center of the field. This is the same as I get from the original image too. I'm thinking that the coordinates reported are correct, but maybe the portion of the image you are interested in is in one of the other HDUs?? Unfortunately, AIJ v3.4 currently only supports the image in the first image HDU encountered. A possible solution is to try to extract the portion of the image you need to a single HDU fits file using a different tool. In the longer term, we are working on an AIJ v5 release. We should be able to support multiple headers in that version eventually, but we can't provide a fix immediately.

Karen