Holcomb Observatory and Planetarium
Telescope with Optics Removed

Holcomb Telescope 2013-15 Major Upgrade

During most of 2013 through part of 2015 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 the spring of 2015.

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.

3.   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.









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.