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Exposure Time
06-06-2014, 15:53
Post: #1
Exposure Time
Does SExtractor take into account exposure times when calculating photometric magnitudes ?

If I have 5 images ( UBVRI ) with exposure times of say ( 120s , 90s , 60s , 30s , 15s ) respectively , and I run SExtractor on these images and return the MAG_ISOCOR values .

Does SExtractor find the EXPTIME in the FITS file Header and take that into account or is there some parameter I should assign Exp. times to ?

Thanks .
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06-10-2014, 21:13
Post: #2
RE: Exposure Time
Hi Derek,

No. The only thing that SExtractor does is to add to -2.5log10(flux) the value set by the MAG_ZEROPOINT configuration parameter.
btw please note that MAG_ISOCOR has been obsoleted. For photometric calibration you might want to use fixed aperture magnitudes (MAG_APER) for instance.
- Emmanuel.
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