Data Taking:
These measurements must be performed under photometric conditions.
BD+17 4708 is the fundamental flux standard of the DES. Due to its pixel scale and short-exposure (< 4-sec) shutter performance, it might not be possible to get a good measurement of BD+17 with the PreCam, but we should try.
Due to the danger of saturating BD+17, it would probably be best to perform these measurements when the Moon is down (at least for g and r filters).
Due to its declination, BD+17 never gets below an airmass of 1.5 at CTIO. We should try to observe BD+17 near its lowest airmass. Here are the airmass tables for BD+17 for each Sunday for September 2010 November 2010, December 2010, and January 2011:
Here is the finding chart for BD+17. The finding chart is 1.6deg x 1.6deg in size, and therefore corresponds to the field-of-view of the PreCam on the Curtis-Schmidt. BD+17 is marked by a blue circle.
Since there is a large (~3 arcmin) gap between the two PreCam CCDs, BD+17 should be centered in one or the other of the two CCDs and not in the gap. Actually, do to the intricate shutter exposure time map, it is probably better to get BD+17 close to the center of the focal plane but without getting into the "gap" -- say, about about 50 pixels from the gap.
Try these exposure times for BD+17:
(g, r, i, z, y) = (1, 1, 1, 1, 1) sec
(g, r, i, z, y) = (2, 2, 2, 2, 2) sec
(g, r, i, z, y) = (3, 3, 3, 3, 3) sec
(g, r, i, z, y) = (4, 4, 4, 4, 4) sec
(g, r, i, z, y) = (5, 5, 5, 5, 5) sec
Data Analysis:
Generally not the responsibility of the observer.
Data analysis will take place off-line.
Try to note which exposures are not saturated in that night's Night Log.