gsreduce task unwieldy
dsmith wrote on Jul 13, 2007
I am wondering whether anyone can help, the problem is with reducing longslit spectra using the gemini>gmos iraf package. Whilst following the instructions to the letter, when I try to bias-correct and flat-field a science frame using gsreduce it gives me the following message:
So I have tried to see what the problem is:
What does this mean? Is it telling me that I need to use a different flatfield? This seems very strange behaviour - any idea how i can get the thing to process? I obviously don't have another set of flats.
Cheers in advance.
Dan
ERROR - GSREDUCE: Grating ID or tilt for image: N20070611S0071 does not match flatfield
ERROR - GSREDUCE: Program execution failed with 1 errors
GSREDUCE done
----------------------------------------------------------------------------
So I have tried to see what the problem is:
gm> imhead N20070611S0071[0] lo+ | grep GRATING
GRATING = 'B600+_G5303' / Grating name
gm> imhead flat[0] lo+ | grep GRATING
GRATING = 'B600+_G5303' / Grating name
gm> imhead flat[0] lo+ | grep TILT
GRTILT = 56.0882 / Grating tilt angle (degrees)
gm> imhead N20070611S0071[0] lo+ | grep TILT
GRTILT = 55.9922 / Grating tilt angle (degrees)
What does this mean? Is it telling me that I need to use a different flatfield? This seems very strange behaviour - any idea how i can get the thing to process? I obviously don't have another set of flats.
Cheers in advance.
Dan
James Turner wrote on Jul 13, 2007
Hi Dan,
Yes, the wavelength of the flat field you are trying to use is not exactly the same as that of the science spectrum. Your observation (#38) alternates between 468 and 473nm. Exposure 71 is at 473nm, so presumably you are trying to use a 468nm flat here. You should instead be using exposure N20070611S0070, which is a flat field taken immediately before exposure 71, at the same setting.
Cheers,
James.
PS. I may not be able to reply to further posts quickly since I'm away from the office (actually on vacation...). Please post any follow-up questions to the Gemini Helpdesk.
What does this mean? Is it telling me that I need to use a different flatfield?
Yes, the wavelength of the flat field you are trying to use is not exactly the same as that of the science spectrum. Your observation (#38) alternates between 468 and 473nm. Exposure 71 is at 473nm, so presumably you are trying to use a 468nm flat here. You should instead be using exposure N20070611S0070, which is a flat field taken immediately before exposure 71, at the same setting.
Cheers,
James.
PS. I may not be able to reply to further posts quickly since I'm away from the office (actually on vacation...). Please post any follow-up questions to the Gemini Helpdesk.
dsmith wrote on Jul 13, 2007
Thanks very much! Sorted!
D
D
Last post on Jul 13, 2007