Dome Flat Shutter Map

Data Taking:

• 1. Data taking is similar but not exactly the same as for the Dome Flat Linearity Test.

  2. During the afternoon (or on a cloudy night), aim the telescope at the flat field screen and turn on the dome flat lamps to a level that is sufficiently dim that a 300-sec exposure will not saturate.

  3. Take this series of exposures (without changing the dome flat brightness):

     • One 300-sec exposure

     • Two 150-sec exposures

     • Three 100-sec exposures

     • Five 60-sec exposures

     • Ten 30-sec exposures

     • Thirty 10-sec exposures

     • Sixty 5-sec exposures

  4. In total, the data taking takes about 1.2 hours to perform.

  5. These only need to be done in a single filter (e.g., i-band).

Data Analysis:

• 1. Generally not the responsibility of the observer.

  2. Bias- and dark-subtract each image.

  3. Median-combine each set of bias-/dark-subtracted exposures of a given exposure length (e.g., median combine the sixty 5-sec exposures, median-combine the thirty 10-sec exposures, etc.).

  4. Divide each of the median-combined images by the bias-/dark-subtracted 300-sec image. These are your dome flat shutter maps.