Project

General

Profile

SN-R1.

The requirement

All SN fields have been observed in griz and processed with DESDM, with the following results:
a. Bad pixels, glowing edges, and saturated pixels are masked.
b. Fields are free of unexpected features which invalidate them as SN fields.
c. Images have a relative astrometric solution accurate to 100 mas RMS. Specifically, this means that the RMS difference in the position of a star on two different SN exposures is less than 100 mas.
d. Images have photometric solutions accurate to 0.05 mag RMS on photometric nights.
e. There is a star catalog that is >95% complete to a stellar magnitude of 20 (in griz filters) and has < 50% galaxy content.

Prerequisites

Observation of the SN fields with the normal exposure times. The first visit to each field should be taken under photometric conditions. A second visit will be required to make most of the comparisons. Reduced images are expected from standard DESDM processing.

Procedure

Visual inspection of the images: check for bad pixels, unexpected bright stars, and other artifacts. The requirements a) and b) are qualitative, so there is a judgement as to whether the quality is acceptable.
The repeatability will be measured by single epoch processing of the SN fields. The deep fields offer multiple exposures of the same field so a comparison can be made using different exposures. The shallow fields will require a second visit to make the comparison.
The star catalog will be ultimately made from the coadd, but could use single epoch data to make an early version. The completeness will be judged primarily by comparison of the DES SN fields that overlap with SDSS stripe 82.

Consequences

The consequences depend on whether it is determined whether the raw images are unacceptable or whether the data analysis is inadequate. In either case, a failure to meet these requirements means that we are not ready to find SN in real time. If the raw image quality is acceptable, we would still want to take data on the SN fields to make deep templates and to improve the analysis for the second year.