Photometry pipeline and general IRAF Q’s!
H.J. van Heerden wrote on May 07, 2007
Hi all
I have been working trhough my research material, and the photometry pipline I'm building to date, and a couple of questions have arizen?
1. When combining frames using combine what would be the "best" reject parameter to use: minmax, ccdclip, crreject, sigclip, avsigclip, pclip?
2. How can I scale darkcombine according to temperature? Our darkframes are temperature "variant".
3. Is there a tool available in IRAF to pick apperture size. How would I go about determining the difference between two appertures, and plotting the difference?
4. Why and how are histograms plotted when determining the FWHM of a star in IRAF?
5. Why and how do photon statistics play a role in the variation of images, and in the core of subtracted psf images? Hope U understand the Q!
6. In general, what can cause variation on ccd chips? Like positional pattern.
7. Finally. Are the same photometric methods applicable on crowded-fields as on non-crowded-fields, i.e. can I use psf-fitting on both?
Thanx for the help
Regards
Pat
I have been working trhough my research material, and the photometry pipline I'm building to date, and a couple of questions have arizen?
1. When combining frames using combine what would be the "best" reject parameter to use: minmax, ccdclip, crreject, sigclip, avsigclip, pclip?
2. How can I scale darkcombine according to temperature? Our darkframes are temperature "variant".
3. Is there a tool available in IRAF to pick apperture size. How would I go about determining the difference between two appertures, and plotting the difference?
4. Why and how are histograms plotted when determining the FWHM of a star in IRAF?
5. Why and how do photon statistics play a role in the variation of images, and in the core of subtracted psf images? Hope U understand the Q!
6. In general, what can cause variation on ccd chips? Like positional pattern.
7. Finally. Are the same photometric methods applicable on crowded-fields as on non-crowded-fields, i.e. can I use psf-fitting on both?
Thanx for the help
Regards
Pat
H.J. van Heerden wrote on May 07, 2007
Hi all
I hope I'm not becoming a burden :cry: , or are the Q's harder than I thought!
Some reaction would be nice, please. :)
If you don't have time, I understand. My time is limited as well. :wink:
Thanx for all the previous help. It is a blessing for the IRAF comunity to have such great support. I deffinatly appreciate it. :D
Thanx
Pat
I hope I'm not becoming a burden :cry: , or are the Q's harder than I thought!
Some reaction would be nice, please. :)
If you don't have time, I understand. My time is limited as well. :wink:
Thanx for all the previous help. It is a blessing for the IRAF comunity to have such great support. I deffinatly appreciate it. :D
Thanx
Pat
Eugene Romas wrote on May 07, 2007
VERY good Qs!!!
Hope, one day answer will be here... ::)
Hope, one day answer will be here... ::)
Last post on May 07, 2007