1. Overview of Lamps and Lamp Usage


We have Ne and Hg emission-line lamps installed in the Andreas Observatory 0.5m topbox. Observers must use caution with the Hg lamp, as it produces bright mid-UV lines that can cause severe eye-damage if viewed directly. Also, as the mercury must be vaporized for the lamp to produce lines, it operates at a very high voltage. The lamps are switched on and off at the telescope. The Hg lamp requires about half a minute to warm up to operating temperature after it is switched on.

The lamps are installed on the left side of the top-box, when viewed from the north with the telescope pointing to the zenith. In order to get the light from the lamps to the detector, one must move a small pick-off mirror into the light path (blocking light from the sky). The pick-off mirror is moved by a hand crank on the left (east) side of the top box. The crank needs to be turned counterclockwise to move the pick-off mirror from the store point to the optical path. During the most recent tests, 24 full turns plus another ~60 degrees were required to move the mirror to the center of the optical path. As there is some play in the pulley system that moves the mirror, one should always begin the observing session by checking the required rotation to move the pick-off mirror into the light path. Do this BEFORE installing the spectrograph on the telescope!

The Hg lamp is much brighter than the Ne lamp, thus one must expose each one separately. When observing with the narrow slit, an exposure of 8 seconds is sufficient for the Hg lamp, while a good spectrum with the Ne lamp takes about 2 minutes. With the wide slit, the exposure times should be about half as long.


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Updated: 2010 July 19 [pbe]