Simple photometry errors question
Gabriel wrote on Feb 23, 2012
Hi,
my question is fairly simple I think. When the photometry process is done, I'm presented with a file containing several columns named:
# 1 object id
# 2 x
# 3 y
# 4 V
# 5 error(V)
# 6 BV
# 7 error(BV)
# 8 UB
# 9 error(UB)
# 10 VI
# 11 error(VI)
The question is: are these errors standard deviations (sigma)? Or should I assume these errors in fact represent the whole range where the actual parameter value (be it V, BV, UB or VI) can exist (ie: ~3*sigma)?
I hope I'm being clear.
I will really appreciate some help on this issue.
Cheers!
my question is fairly simple I think. When the photometry process is done, I'm presented with a file containing several columns named:
# 1 object id
# 2 x
# 3 y
# 4 V
# 5 error(V)
# 6 BV
# 7 error(BV)
# 8 UB
# 9 error(UB)
# 10 VI
# 11 error(VI)
The question is: are these errors standard deviations (sigma)? Or should I assume these errors in fact represent the whole range where the actual parameter value (be it V, BV, UB or VI) can exist (ie: ~3*sigma)?
I hope I'm being clear.
I will really appreciate some help on this issue.
Cheers!
Mike Fitzpatrick wrote on Feb 23, 2012
Looking at the code for EVALFIT/INVERTFIT, it appears to be the standard deviation.
Gabriel wrote on Feb 23, 2012
Thanks fitz.
Shouldn't such a sensitive parameter be more clearly described in the manuals/help files? I think it's quite an issue when even you, one of the people with more knowledge about IRAF, can't be totally sure if that number actually represents the standard deviation or some other value...
Cheers,
Gabriel
Shouldn't such a sensitive parameter be more clearly described in the manuals/help files? I think it's quite an issue when even you, one of the people with more knowledge about IRAF, can't be totally sure if that number actually represents the standard deviation or some other value...
Cheers,
Gabriel
Last post on Feb 23, 2012