Variable PSF
Gabriel wrote on Jul 16, 2009
Hi all,
I'm trying to perform photometry on frames with a variable PSF.
I found this on' A User's Guide to Stellar CCD Photometry with IRAF' by Massey & Davis:
The worst thing to find at this point is that there is a systematic pattern with position on the chip. This would indicate that the PSF is variable. There is the option for making a variable PSF, but the assumption is that the PSF varies smoothly in x and y; usually this is not the case. (In the case of the nonÂflat TI chips the variations are due to the potatoÂchip like shape.) If you do decide the PSF is variable, be sure to use plenty of stars in making the PSF. As it says in the "help page'', twenty-five to thirty is then not an unreasonable number. If that doesn't scare you off, nothing will.
Now, I can't find the variable PSF option anywhere. Could somebody point me in the right direction?
One more thing, where can I get this article?:
http://adsabs.harvard.edu/abs/1994awca.conf...72S
(Title: Photometry with a Variable PSF; Authors: Stetson, P. B.)
Thanks!
Gabriel
I'm trying to perform photometry on frames with a variable PSF.
I found this on' A User's Guide to Stellar CCD Photometry with IRAF' by Massey & Davis:
The worst thing to find at this point is that there is a systematic pattern with position on the chip. This would indicate that the PSF is variable. There is the option for making a variable PSF, but the assumption is that the PSF varies smoothly in x and y; usually this is not the case. (In the case of the nonÂflat TI chips the variations are due to the potatoÂchip like shape.) If you do decide the PSF is variable, be sure to use plenty of stars in making the PSF. As it says in the "help page'', twenty-five to thirty is then not an unreasonable number. If that doesn't scare you off, nothing will.
Now, I can't find the variable PSF option anywhere. Could somebody point me in the right direction?
One more thing, where can I get this article?:
http://adsabs.harvard.edu/abs/1994awca.conf...72S
(Title: Photometry with a Variable PSF; Authors: Stetson, P. B.)
Thanks!
Gabriel
Gabriel wrote on Jul 16, 2009
I've found that option: 'daopars.variable'.
If anybody has access to the article though, I'd really appreciate if you could let me know where I can get it.
Cheers!
Gaba
If anybody has access to the article though, I'd really appreciate if you could let me know where I can get it.
Cheers!
Gaba
Last post on Jul 16, 2009