Centennial Observatory FAQ

The Centennial Observatory -
Frequently Asked Questions

Q: What kind of telescope is in the observatory?

A: The main instrument is the Norman Herrett Telescope, a 24" f/8 Ritchey-Chrétien reflector on a computer-controlled equatorial fork mount, manufactured by DFM Engineering of Longmont, Colorado, USA.  The guide telescope is a Meade 5" f/9 apochromatic refractor.  Also piggybacked to the 24" is a Takahashi Epsilon 180ED hyperbolic astrograph (7", f/2.8) for wide-field views.

Additional telescopes include:

  • A JMI NGT-18 18" f/4.5 Newtonian
  • A Questar 7" Maksutov
  • Two Questar 3.5" Maksutovs
  • A Celestron Ultima 11 Schmidt-Cassegrain
  • A Meade 10" LX200GPS Schmidt-Cassegrain
  • A Meade 10" LX5 Schmidt-Cassegrain
  • A Meade 8" LX10 Schmidt-Cassegrain
  • A Celestron 8" C-8 Schmidt-Cassegrain (on loan from Dr. Alan Frost)
  • A Coronado 60 mm SolarMax II hydrogen-alpha solar telescope

Q: When is the observatory open?

A: The observatory is open for public viewing at the following times, weather permitting:

  • Free star parties on the Second Saturday of each month, from one hour after sunset to midnight.
  • After the bimonthly astronomy talk, presented on the Thursday nearest the new moon in odd months.
  • During the summer months (Memorial Day to Labor Day) free solar viewing is offered each Wednesday afternoon from 1:30 to 3:30 PM.
  • From November through February, viewing is offered on the second and fourth Tuesdays of the month from one hour after sunset to 9:00 PM.
  • Whenever special events (eclipses, bright comets, etc.) are happening in the sky.

Q: Why was the observatory built in a place with so many lights around?

A: The primary philosophy of the Herrett Center's observatory may be summed up in a single word: Access.  While a dark-site observatory would offer a greater number of celestial targets to view, its remoteness would limit the number of people who would use it.  By locating the observatory at the museum, the easy access and convenience gives many people who might never have the opportunity to see through a large telescope an opportunity to do so.  Should this experience pique their interest in seeing more, Idaho is fortunate to have a public dark site observatory at Bruneau Dunes State Park near Mountain Home, Idaho, one hour to the west.

Q: Are there plans to improve the lighting on the campus to reduce their impact on the observatory?

A: Yes.  In 2012, full cut-off shields were added to the parking lot lights nearest the observatory to direct light downward and prevent light trespass into the observatory.  Walkway lighting on campus has also been replaced with night-sky friendly fixtures, and the LEED certified HSHS and ATIC buildings on the northeastern part of the CSI campus feature all night-sky friendly outdoor lighting.  Lighting from nearby sports venues remains a challenge.

Q: Is there an admission fee to visit the observatory?

A: Star parties on the second Saturday of each month are free, as are solar viewing sessions (held on Wednesday afternoons, 1:30 to 3:30 PM, from Memorial Day to Labor Day).  Viewing sessions following monthly astronomy talks are $1.50 per person, or free with admission to the talk or a planetarium show.   A $1.50 admission fee is charged for viewing sessions held on the second and fourth Tuesdays of the month, November through February, from one hour after sunset to 9:00 PM.

Q: Can the telescope be operated remotely?

A: The telescope is equipped with a CCD camera to allow remote operation in the future.  Currently, staffing limitations and firewall security issues prevent this mode of operation from being implemented.

Q: Is the telescope wheelchair accessible?

A: Very much so!  An elevator takes visitors to the upper floor.  From there, a wheelchair lift is available to access the observing deck.   The telescope features a unique optical "periscope" which allows viewing from a seated position.

Q: Are there restroom facilities available?

A: Yes.  A unisex, wheelchair-accessible restroom is availble in the observatory lobby adjacent to the dome.

Q: Is the observatory heated/air conditioned?

A: In order to preserve undisturbed air around the telescope, and allow the optics to stabilize at ambient temperatures, the observatory dome and lobby area are not temperature controlled.  Fans circulate outside air through the dome to maintain temperatures around the telescope as close as possible to the outside ambient temperature, so please dress for outdoor temperatures when you visit!

Q: Is observatory used for astronomical research?

A: Currently, research at the observatory comprises the measurement of asteroid diameters via stellar occultation timing, using a high-gain video camera and GPS timing device.  While light pollution limits the types of research that may be performed from the site, the observatory's high-quality CCD camera may be used for variable star/active galactic nucleus monitoring, lunar occultation studies, and photometric searches for transiting extrasolar planets.

Q: Are star parties rescheduled in the event of bad weather?

A: If weather turns bad, star parties are cancelled.  Lectures are presented rain or shine (unless weather forces the campus or local roads to close).

Q: What imaging equipment is available for the telescope?

A: The primary imaging instrument is an Apogee Alta E47+, a 1024x1024, back-illuminated, thermoelectrically cooled, 16-bit CCD camera.  Video imaging is accomplished with an Adirondack Video Astronomy StellaCam II and a Color PlanetCam.  An Olympus OM-1 SLR camera body is available for prime focus and eyepiece projection film photography.

Q: Can the telescope send an image into the planetarium?

A: The telescope is equipped with video cameras designed for astronomical imaging.  Images from these cameras can be sent to the planetarium and displayed in a rectangular frame which may be scaled and positioned any where on the dome.  With the exception of bright targets (e.g. planets and the moon), real-time color images are not possible, requiring time exposures and images shot through several color filters to be stacked and post-processed.  A live projection from a telescope covering the entire dome is not possible due to the high resolution required (4k by 4k pixels, roughly twice that of Full HD) and the fact that telescopes necessarily produce a narrow field of view which require sophisticated "warping" to cover a hemispherical dome without appearing highly distorted.

Q: How far can the telescope see?

A: Light pollution is the limiting factor.  In late spring, observers can easily see 3C273, the brightest quasar, whose light requires about 2.2 billion years to reach Earth.  The CCD camera can image much fainter targets than the human eye (by at least a factor of 250), allowing it to image considerably more distant targets.  So far the faintest objects imaged are approximately magnitude 20, but it is probably possible to go several magnitudes fainter with longer exposure times.