Question on subtracting background in IMEXAMINE task
mdivell wrote on Jul 05, 2010
Hi all,
I'm working on a photometry project where there was no detection in our science frames. Obviously I'm limited to calculating an upper limit.
I have measured the flux from a standard star in ADU, used the known flux value to calculate a conversion factorusing the IMEXAMINE task and (hopefully) reasonable parameters in regards to aperture size, etc. (rimexam parameters)
Wanting to calculate the flux necessary for a 3-sigma detection in the science frame, using the same aperture size from the standard star (same radius, buffer and width, with 1 iteration so it doesn't try to modify these values). Finally, my question: should the background paramter in rimexam task be set to yes, or no?
Normally, for a star, the background would be removed so that only flux from the star is measured. But in the case of calculating an upper limit, the signal IS the background, so would it be the background that I'm measuring?
It makes quite a difference: 12.9 mag vs. 14.9 mag. Advice is appreciated!
I'm working on a photometry project where there was no detection in our science frames. Obviously I'm limited to calculating an upper limit.
I have measured the flux from a standard star in ADU, used the known flux value to calculate a conversion factorusing the IMEXAMINE task and (hopefully) reasonable parameters in regards to aperture size, etc. (rimexam parameters)
Wanting to calculate the flux necessary for a 3-sigma detection in the science frame, using the same aperture size from the standard star (same radius, buffer and width, with 1 iteration so it doesn't try to modify these values). Finally, my question: should the background paramter in rimexam task be set to yes, or no?
Normally, for a star, the background would be removed so that only flux from the star is measured. But in the case of calculating an upper limit, the signal IS the background, so would it be the background that I'm measuring?
It makes quite a difference: 12.9 mag vs. 14.9 mag. Advice is appreciated!
mdivell wrote on Jul 05, 2010
Parameters for task: rimexam
banner = yes
title =
xlabel = Radius
ylabel = Pixel value
fitplot = yes
fittype = moffat
center = yes
backgro = ????
radius = 15
buffer = 10
width = 15
iterati = 1
xorder = 0
yorder = 0
magzero = 25
beta = 2.19
My FWHM of the standard star is 5.05
banner = yes
title =
xlabel = Radius
ylabel = Pixel value
fitplot = yes
fittype = moffat
center = yes
backgro = ????
radius = 15
buffer = 10
width = 15
iterati = 1
xorder = 0
yorder = 0
magzero = 25
beta = 2.19
My FWHM of the standard star is 5.05
Last post on Jul 05, 2010