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Holcomb Telescope 2013 Major Upgrade
During most of 2013 the 38-inch Cassegrain telescope at Holcomb
observatory will be undergoing a major upgrade. This upgrade will
allow the telescope to go seamlessly from public viewing to
research mode in a matter of seconds. The planetarium shows and
telescope viewing will continue as usual and patrons will still be
able to visit the dome of the observatory to view the telescope as
it is being upgraded. We will be using a portable Meade
telescope that is computer controlled and is of good sized. Thus
visitors will be able to view the stars, planets, and Moon much
better than a typical backyard telescope. The 38-inch
telescope is expected to be back online in late 2013.
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The last major upgrade to the Holcomb telescope was in
1997. Since then age has taken its toll on the equipment and
operation. Thus several years ago we began planning for
the current refurbishment. Funding for this project was
provided by former Butler physics student Dr. Frank Levinson
through the Silicon Valley Community Foundation. The $325,000
of funding will allow us to bring the telescope into the 21st
century to better suit the needs of our students and faculty along
with keeping James Holcomb's original intent for the observatory,
our continuing tradition of educating the public about the
cosmos.
Astronomical
Consultants and Equipment, Inc. (ACE) out of Tucson, AZ have
been contracted to complete the refurbishment. They
have built and refurbished numerous telescopes throughout the world
including our SARA telescopes located at Kitt Peak,
AZ and Cerro Tololo Chile. They will be constructing
customized equipment for the Holcomb telescope in addition to
providing an integrated control system. One key goal of the
proposed refurbishment is to have the Holcomb Telescope operations
be identical to those of the SARA telescopes, so that our students
can use the same seamless interface when observing. These upgrades
include:
1. The Holcomb Observatory
Dome -
The dome requires major refurbishment to permit automatic opening
and closing, and synchronized tracking with the telescope. ACE has
performed similar work on scores of other ASH domes. The
system will also have the ability to automatically shutdown in case
of impending inclement weather thus protecting the telescope.
2. The Telescope Optics
and Secondary Mirror
- The size of Charge
Coupled Device (CCD) detectors has dramatically increased in the
last two decades. It is now possible to deploy large format CCDs
that can take images of a relatively large area of the sky. To make
the most use of the telescope, ACE will reconfigure the optics by
implementing a new secondary mirror that will turn the system into
a relatively fast, wide-field instrument, matched to modern
electronic detectors. The new configuration will be an f/7.5
system, which in combination with new large-format CCD, will allow
us to image an area 16 times that of the present optical design.
This will dramatically increase the research ability of the
telescope.
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Primary Mirror Cell and Mirror Cover
- The primary
mirror cell of the Holcomb Telescope is rather primitive. It
attaches to the rear of the main tube using just three pairs of
push-pull screws. The primary mirror is optically collimated using
these screws. It is a very awkward arrangement that makes
collimation nearly impossible, because, as the cell is tilted, so
is the CCD detector. This has led to significant image degradation
due to the lack of proper collimation. Holcomb's primary mirror
cell instrument mounting interface is inadequate, and the clearance
between the cell and the yoke of the fork arms is very small. All
of these problems will be addressed by installing a new mirror
cell. A motorized mirror cover will also be employed to protect the
mirror when the telescope is not in use. |
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4.
Instrument Box - In the present
setup to use the telescope for research, the eyepiece box must be
removed so that the camera can be attached. This procedure is not
ideal due to the expense of the camera ($30,000) and possible
damage. More than once, the camera has been sent back to the
manufacturer for repair of damages caused during repeated removal
and attachment. The present instrument box setup also prevents the
use of an off-axis guider needed for long exposures. To
correct these problems, a new instrumentation box will be designed
and fabricated with dual filter wheels containing 10 slots for 50mm
square filters. The box would have an X-Y autoguider stage and/or
an eyepiece port for public viewing. A flip mirror will permit
viewing either through the eyepiece or main CCD. This would
allow the telescope to be easily shifted from public outreach to
research mode.
5. Remote
Telescope Operation -
Presently, the Holcomb Telescope can only be operated from the
second floor office of the Holcomb Observatory. Though useful in
the majority of situations, this limits several aspects of both
public observing and research.
Ideally, Butler would like to have a telescope that could be put
into research mode within five minutes by an observer at another
location. This would allow us to observe more quickly changing
phenomena. For an example, gamma-ray bursts occur at random
typically once a day. It is of the utmost importance to observe
these with optical telescopes within an hour to examine the fading
afterglow of these colossal events. This new remote mode will
allow us to use the telescope from a classroom on the other side of
campus.