University of Virginia, College and Graduate School of Arts and Sciences

40-inch Astrometric Reflector

The University of Virginia operates a 40-inch (1 meter) telescope at Fan Mountain Observatory, about 15 miles south of Charlottesville. The telescope is an astrometric reflector, originally designed for use with photographic plates as part of UVa‘s ongoing tradition of precision astrometry. In recent years, however, extensive hardware upgrades and instrumentation efforts have transformed the observatory into a more modern research facility capable of optical CCD imaging and stellar spectroscopy.

Specs

General System Data: Baker-Schimdt system

Effective focal ratio - f / 13.534

Effective focal length - 541.3764 inches (13.75096 meters)

View Optical layout

Focal Plane:
Cassegrain focus - Photographic Plates

  • Field Diameter - 8 inches
  • Angular Field Diameter - 50.8 arcmin
  • Plate Scale - 15.000 arcsec/mm

Focal Plane:
Cassegrain focus - SITe 2048 x 2048 CCD

  • Field Diameter - 2 inches
  • Angular Field Diameter - 12.3 arcmin
  • Plate Scale - 0.36 arcsec/pixel
  • Filter wheel 1 - 3 x 6" filters (Washington + DDO51)
  • Filter wheel 2 - 5 x 4" filters (UBVRI and H alpha + cont.)

Optics

General System Data: Baker system

  • Effective focal ratio - f/13.534
  • Effective focal length - 541.3764 inches
  • View Optical layout

(1) Corrector Lens: aspheric-plano

  • Outer Diameter - 43.5 inches
  • Thickness - 1.131 inches
  • Clear Aperture - 40 inches
  • Material - UBK-7

(2) Primary Mirror: aspheric

  • Outer Diameter - 43.5 inches
  • Inner Diameter - 14.0 inches
  • Thickness - 7 inches
  • Clear Aperture - 43.060 inches
  • Radius of Curvature - 651.64 inches
  • Material - ULE
  • Reflective coating - Aluminum

(3) Secondary Mirror: aspheric

  • Outer Diameter - 19.25 inches
  • Thickness - 2.5 inches
  • Clear Aperture - 19.00 inches
  • Radius of Curvature - 651.64 inches
  • Material - ULE
  • Reflective coating - Aluminum

(4) Focal Plane: Cassegrain focus

  • Field Diameter - 8 inches
  • Angular Field Diameter - 50.8 arcmin
  • Plate Scale - 15.000 arcsec/mm

A ZEMAX lens file for the 40-inch is available. It is at present, however, only an approximation of the actual optical layout. It was created using ZEMAX version 8.0. This file can be saved in text format and read directly into ZEMAX for further analysis.


Instrument

The 40-inch telescope is an astrometric reflector originally designed to continue UVa's long tradition of precision astrometry farther away from the growing Charlottesville area where light pollution was less of a factor. The telescope has an f/13.5 Cassegrain focus with a 15.0 arcsec/mm focal plane that is very flat over an area 8 inches in diameter. This large focal plane was useful during the telescope's earlier days when photographic plate imaging was done. The instruments used at the 40-inch today, however, make use of only the central portion of the focal plane.

Instrument Description Specs Local
 Ref.
Notes Status
CCD Gen I Direct SITe Generation I CCD Camera Direct CCD Specs CCD Direct Webpage A Operational
CCD Gen II Direct SITe Generation II CCD Camera Direct CCD Specs CCD Direct Webpage B Operational
FOBOS Single Object Fiber Spectrograph FOBOS Specs FOBOS Webpage C Operational
EYE 2-inch Eyepiece EYE Specs EYE Webpage D Operational

NOTES

A. The GenI camera is used for optical imaging. It houses a science grade, single amplifier SITe 2048x2048 CCD mounted in an IR Labs dewar controlled by SDSU CCD Laboratory Generation I electronics.

B. The GenII camera is used with the FOBOS spectrograph. It houses an engineering grade, quad amplifier SITe 2048x2048 CCD mounted in an IR Labs dewar controlled by SDSU CCD Laboratory Generation II electronics. Note, however, that the CCD is generally operated using either one or two amplifiers.

C. FOBOS is a single-object, fiber-fed spectrograph intended for moderate resolution stellar spectroscopy. Detailed information about the instrument can be accessed through the following link: FOBOS.

D. There is currently one eyepiece available for the 40-inch, used primarily for public outreach.

Filters

Two filter wheels in the telescope's tailpiece allow for five 4-inch filters and three 6-inch filters to be loaded simultaneously. Available filters include Johnson UBV, Cousins RI, Washington C, M, T1, and T2, DDO51, and H-alpha.

 

Additional filter information

The old control room WHITE BOARD (erased November 18, 2004), with historical focus data, etc.

Observing Tools

Coordinates -78° 41.6' East Longitude
+37° 52.7' Latitude
Elevation 556 meters above sea level
Zone time (runs for 10 sec)
Universal time (runs for 10 sec)
Sidereal time If you don't see a clock here, then your browser does not support Java. 
Sunset/Sunrise 2001 | 2002 | 2003 | 2004 | 2005 | 2008 | 2009 | 2010
Astronomical Twilight 2001 | 2002 | 2003 | 2004 | 2005 | 2008 | 2009 | 2010
Moonset/Moonrise 2001 | 2002 | 2003 | 2004 | 2005 | 2008 | 2009 | 2010
Moon Illumination 2001 | 2002 | 2003 | 2004 | 2005
Current lunar phase
Airmass info Table of airmass vs. Dec/HA
GIF plot of airmass vs. Dec/HA
PS plot of airmass vs. Dec/HA
Weather info Allsky camera at the station house
Telemetry from the Fan Mountain Observatory Environment Monitoring System