Zeropoint results (Nov 3, 2012 courtesy Paul Martini)
Two datasets on C26202 were obtained on 20121102, the first at airmass 1.01 (g->Y in files 145966->145970) and the second at 1.11 (g->Y in files 146108->146112). The zeropoints are consistent to better than 0.05 mag, with the exception of r-band. The average of the two zeropoints correspond to:
|Filter||Zpt (mag)||Zpt (e-)||Zpt (e-)/Expected|
Zpt (mag) is the AB magnitude that corresponds to 1 DN/s. Zpt (e-) is the number of e-/s that corresponds to AB=20 mag as assumes the gain is 4.5e-/DN. Zpt (e-)/Expected is the ratio of Zpt (e-) to the expected zeropoints calculated by Huan Lin.
Notes about the analysis:
- No airmass correction was applied, although this should be minimal.
- In all cases C26202 fell on Amp A of chip N4.
- The astrometric solution in the headers are off by 3.8' and 3'.
- While the last column indicates the performance exceed expectations, the specification is for airmass 1.3, while these data were obtained at about airmass 1.