Instrument Science Report 2001-04:

Preliminary Assessment of the FR533N Filter Anomaly

S. Gonzaga, S. Baggett, and J. Biretta

April 12, 2001

Abstract:

Analysis of FR533N VISFLAT images has revealed an apparently randomly occuring rotational offset of about 0.5 degrees in some images, a quantity that corresponds to one filter step. The pivot point of the rotation implicates the filter wheel as the source of the inconsistency. We expect no impact on observations as any photometric effect is less than 1%. A cursory check of several other filters (on other filter wheels), shows no similar problem. At this time, the source of this anomaly, whether it is mechanical or due to a software error, is unknown.

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