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Point-R1

RMS absolute pointing errors are less than 10".

This requirement applies to the telescope boresight (right?).
The 10" figure is the maximum, not rms, error, and is radius.

Prerequisites

Telescope pointing model has been created.
Telescope pointing info in FITS header.
Geometric location of N4, S4 CCDs has been established.
NOMAD catalog
Access to SkyView website
Code to perform extract stars from images and perform a quick astrometric analysis.

Procedure

[The following procedure does not assume Data Management astrometric processing is functioning yet.]
Obtain r-band images using standard survey exposure times (80 sec) at a grid of locations around the sky extending to zenith angles of 60 degrees and at all azimuths. It is likely that most, if not all, data can be taken from SV exposures planned for other purposes.

Verdict

Compute the mean and peak deviation of residuals of the astrometric solution relative to the indicated telescope position. Exclude any spurious astrometric solutions. Peak must be < 10" radius.

Consequences

Bad pointing means that a) the DES tiling efficiency will degrade; b) it will not be possible to identify guide stars or F/A stars based on telescope pointing info alone. The guider may not be able to operate at all due to the need to find stars from full-frame information. The F/A processing will also be slowed, meaning that tweaks to the focus may not occur.

Reports