The Sky Survey Replaces its Monitor Telescope:
The New Photometric Telescope
The 0.5-meter telescope from Johns Hopkins
arrived at Apache Point in perfect condition, and was installed on
schedule (as shown to the right) in mid-August. However the transfer
plans were nearly upset by the World Lacrosse Championship held in
Baltimore that same week! One of the lacrosse fields used in the
tournament is near the JHU astronomy building, so the telescope
transport crew wasn't allowed to close the road to the observatory.
The telescope fit inside the dome only after some minor
modifications. Because the new telescope is taller than the original,
Mark Klaene from APO and John Briggs from Yerkes had to lower the
concrete pier. They also added a mounting wedge to correct for the 6.5
degree latitude difference between Baltimore and Apache Point.
The optics and instrumentation of the 0.5-meter telescope had been
originally designed for less-demanding student use. In particular, its
useful field of view was too small for SDSS purposes. To solve this
problem, Shu-i Wang from Yerkes designed a set of field corrector
optics, which have enlarged the usable field of view to nearly 1 degree
across. Alan Uomoto from JHU has designed a new instrument box, and
Takashi Ichikawa, from the Japan Participation Group, built a new
shutter. Within two months, the modifications will be complete and can
then be tested.
And the price tag on this replacement? Alan Uomoto says, "The total
cost is $300,000, three-quarters of it for purchasing a replacement
telescope for JHU which, ironically, will have exactly the optics that
SDSS would've wanted."
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