| SDSS uses a small telescope at Apache Point Observatory to monitor sky conditions, create the primary standard star system, and observe stars for calibrating 2.5 m telescope images. The original "Monitor Telescope" (seen here being inspected by John Briggs, Yerkes Observatory telescope engineer) was a 24-inch f/10 built by Autoscope. Unfortunately, this instrument never performed properly so we decided to replace it with a 20-inch telescope that was currently in use at the Johns Hopkins University Maryland Space Grant Observatory. An article at the SDSS web site explains in more detail our decision to use the JHU telescope. |  |
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The JHU telescope was built by DFM Engineering in
1991 and moved to Apache Point in August 1998. Its closed tube design
provides better light shielding than the old telescope, an important feature
that helps guarantee measurment accuracy by keeping stray light off the
detector.
It was featured in an oddly prescient sidebar in the Johns Hopkins Magazine about high speed networking. The magazine wanted a photo of an APO telescope but used instead the campus teaching telescope (we didn't know we were going to move that telescope when the photo was taken). |
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updated September 11, 1999