Orbiting Astronomical Observatory 2


Orbiting Astronomical Observatory 2
Mission typeAstronomy
COSPAR ID1968-110A
SATCAT no.3597
Spacecraft properties
Dry mass2,012 kilograms (4,436 lb)
Start of mission
Launch date7 December 1968, 08:40:09 (1968-12-07UTC08:40:09) UTC
RocketAtlas SLV-3C Centaur-D
Launch siteCape Canaveral LC-36B
End of mission
Last contactJanuary 1973 (1973-02)
Orbital parameters
Reference systemGeocentric
RegimeLow Earth
Perigee altitude768 kilometres (477 mi)
Apogee altitude777 kilometres (483 mi)
Inclination35.0 degrees
Period100.30 minutes
Epoch6 January 1969[1]

The Orbiting Astronomical Observatory 2 (OAO-2, nicknamed Stargazer) was the first successful space telescope (first space telescope being OAO-1, which failed to operate once in orbit), launched on December 7, 1968.[2] An Atlas-Centaur rocket launched it into a nearly circular 750-kilometre (470 mi) altitude Earth orbit.[3] Data was collected in ultraviolet on many sources including comets, planets, and galaxies.[2][4] It had two major instrument sets facing in opposite directions; the Smithsonian Astrophysical Observatory (SAO) and the Wisconsin Experiment Package (WEP).[4] One discovery was large halos of hydrogen gas around comets,[4] and it also observed Nova Serpentis, which was a nova discovered in 1970.[2]

Celescope: Smithsonian Astrophysical Observatory

The Smithsonian Astrophysical Observatory, also called Celescope, had four 12 inch (30.5 cm) Schwarzschild telescopes that fed into Uvicons.[5] Various filters, photocathodes, and electronics aided in collecting data in several ultraviolet light passbands.[5] The experiment was completed in April 1970.[5] By the time it finished about 10 percent of the sky was observed.[5] The Uvicon was an ultra-violet light detector based on the Westinghouse Vidicon.[6] Ultraviolet light was converted into electrons which were in-turn converted to a voltage as those electrons hit the detection area of the tube.[7] There has been a Uvicon in the collection of the Smithsonian Institution since 1973.[6]

Wisconsin Experiment Package

The Wisconsin Experiment Package had eleven different telescopes for ultraviolet observations.[8] For example, there was a photoelectric photometer fed by a 16-inch (40.64 cm) telescope with a six-position filter wheel.[8] WEP observed over 1200 targets in ultraviolet light before the mission ended in early 1973.[4]

Spacecraft bus

The observatory was overall about 10 ft by 7 in the shape of an octagonal prism and it weighed 4400 pounds.[9]

See also


  1. ^ McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Retrieved 12 October 2013.
  2. ^ a b c Joseph A. Angelo (2014). Spacecraft for Astronomy. Infobase Publishing. p. 20. ISBN 978-1-4381-0896-4.
  3. ^ Gunter – OAO-2
  4. ^ a b c d Orbiting Astronomical Observatory OAO-2
  5. ^ a b c d High-Resolution Telescopes
  6. ^ a b "Detector, Uvicon, Celescope". National Air and Space Museum. 2016-11-24. Retrieved 2018-01-24.
  7. ^ [1]
  8. ^ a b Wisconsin Experiment Package
  9. ^ "OAO-2". Space Based Telescopes. Retrieved 2018-10-25.

External links

  • OAO 2 observations of the Alpha Persei cluster
  • OAO-2 Info and pics
  • 50th Anniversary Overview of OAO-2 including video