Gary Bernstein, 08/28/2012 10:38 AM
_"It is known whether 1st-year photometric accuracy will be enhanced by targeting standards fields in the middle of nights in addition to evening/morning twilight standards. "_
* Zeropoints and extinction coefficients calculated for all standards-field exposures during SV
* RASICAM data in hand.
* Compare middle-of-night zeropoints and extinctions coefficients to mean of morning/evening twilights.
* Calculate RMS deviation of midnight to twilight zeropoints, evaluate statistical significance.
* For cases where midnight standards differ from the twilights signfiicantly: what conditions indicated by RASICAM?
* Use night of hourly standards to determine whether midnight standards improved ability to interpolate proper zeropoint to hourly standards.
* If there is no detectable difference between midnight and twilight photometric solutions, except in cases where RASICAM indicates non-photometric conditions, then midnight standards are superfluous.
* If midnight standards differ from twilights, but hourly variations are seen to be equally large, then midnight standards are superfluous since they cannot track the night's photometric variations anyway.
* Absence of photometric variation between twilights means that DES observations need to explicit nighttime standards.
* Fast photometric variations will have impact on ubercal algorithms' assumptions.
* Useful midnight standards should be incorporated into OBSTAC algorithm, that some field with standards gets observed near middle of photometric nights.