Affiliation
American Association of Variable Star Observers (AAVSO)
Tue, 10/20/2015 - 23:15
I had an email exchange with Richar Berry about calibration. (Good exchange, he was helpful.) When I use AIP4WIN to do my calibration and then port the images to VPHOT, VPHOT does not see the images as calibrated. In short: it does not pick up the HISTORY keyword. Richard suggests that VPHOT recognizes another keyword. I have not had this problem with other reduction packages, and I simply march forward knowing that my images are calibrated inspite of the fact that VPHOT does not recongize this fact. Anyone have a insight into the problem? On the VPHOT end? (If so, is it a simple fix?) On the AIP4WIN side? (If so, what is the modification needed?) Inquiring minds want to know.
Ed
Ed:
VPhot looks for CALSTAT='BDF'. History doesn't work.
Maxim adds that Keyword.
Can you optionally add extra Keywords to the Fits Header with AIP4WIN?
Ken
PS: As you noted, you know your images have been calibrated but I understand you would like to see a green calibration box rather than red in VPhot!
Hi Ed,
As Ken stated, VPhot wants to see CALSTAT = 'BDF' in the header, for calibration status = bias, dark, flat (I believe). There may be other header modifications that are recognized by VPhot for this purpose, but that one certainly works.
The problem for AIP users is that the AIP option for editing the header (Edit>FITS Header) doesn't work, at least it doesn't work in any version of AIP that I have tried (up to 2.4.0). When you try to edit the header the new text appears, but it doesn't get saved. This is a known bug, but as far as I know it has not been fixed, so you just have to use another program to do that.
On my Mac I use a program called "fv" to modify the header. This requires X11. Some Mac's have X11 as part of the OS; some don't, so if you're using a Mac you may need to download some version of X11. I use "XQuartz".
Phil
Don't forget about the FITSIO library that has subrountines and functions useful for editing fits headers:
http://heasarc.gsfc.nasa.gov/fitsio/fitsio.html
One of the example programs, modhead, basically does what you want:
http://heasarc.gsfc.nasa.gov/docs/software/fitsio/cexamples.html#modhead
Hi Ed, all
I wrote a Python script awhile ago that I use as part of my DSLR photometry process. One thing it allows you to do is set CALSTAT.
https://github.com/dbenn/photometry_tools/blob/master/modify-fits-heade…
So you can say something like this:
to set the CALSTAT value in the FITS headers of multiple FITS files.
David
I most recently ran a folder of image files thru CCDSoft that had a routine in the 'Research' tab that allowed me to set "CALSTAT = BDF ".
Lew
Question: Does CALSTAT recognize any combination of BDF: for example "DF" (dark integration equal to light integration) or even just "D" (dark only)? Or does it recognize only BDF?
Ed
Ed:
It understands any combination of BDF.
Shows red, yellow or green in VPhot calibration box based on none or partial or all.
Ken
If the integration times are the same, is there ANY difference between BDF and DF?
Lew:
No difference if same integration time for dark and light. I often run different times so need B too.
Ken
OK, that answers my question, any combination will do. From what you said, I assume BF would turn up yellow. I think that is fine so long as you know light and dark integration times are the same.
To Lew and others: I had to understand what CALSTAT recognizes, not because of my calibration steps but to encourage Richard Berry to incorporate CALSTAT into the AIP4WIN fits header.
Ed