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General

Profile

Point-R4

The time from the issuance of a 2 degree slew to the opening of the shutter is no more than 20 seconds. Telescope encoders do not record pointing deviations of more than 0.2” from commanded position in the 5 seconds after the shutter opens.

Prerequisites

Point-R1
SISPI operational with guiding enabled
Two target observations separated by 2 degrees

Procedure

Take back to back observations of target fields that are separated by 2 degrees
Check SISPI logs for the time when the shutter closes on one observation, and compare to time when shutter opens for the next one
Guiding software stamps out stars at 1 Hz, so analyze the guide star locations on the first 5 stamps

Verdict

Time from shutter closing to opening for the next observation should be less that 20 seconds
Guide star locations in the guiding stamps should not deviate by more than 0.2" for the first 5 stamps

Consequences

Survey speed with be delayed if it takes longer to slew than 20 seconds. This reduces the number of exposures possible in a night. Also, guiding errors at the start of the exposure will contribute to the PSF of the images.