DENSEPAK and Hale-Bopp

The Densepak is a fiber optic cable for the Multi-Object Spectrograph ( MOS ) of the WIYN telescope. It currently attaches to the Nysmith port normally used for imaging. It provides an array of 90, three arc second fibers in a hexagonal packing on 4 arc second centers. The 7 X 13 fiber array (one fiber is broken) thus covers roughly 60% of a 30 X 40 arc second field of views. As with the Hydra, this fiber cable runs down to the MOS room at ground level and can be used interchangeably with the Hydra .

The Densepak array is illustrated below:

Click here for a full sized PostScript file

The Densepak became available in 1997 March and was used for Comet Hale-Bopp on four nights. the observation strategy was to place the comet nucleus successively in each of the 4 conrners of the denspak array. These exposures were typically 60 seconds. We then stepped away from the nucleus in the Sun and Anti-Sun directions by roughly the width of the array. Exposures were incrreased as we moved to greater distances. For morning twilight operations the frames at up to 3 arc minutes from the nucleus were done first and we stepped inward. Frames several degrees away from the comet were taken before, in the middle and after the comet observations.

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