Orbiting Astronomical Observatory 2

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Orbiting Astronomical Observatory 2
Mission type Astronomy
Operator NASA
COSPAR ID 1968-110A
SATCAT no. 3597
Spacecraft properties
Manufacturer Grumman
Dry mass 2,012 kilograms (4,436 lb)
Start of mission
Launch date 7 December 1968, 08:40:09 (1968-12-07UTC08:40:09) UTC
Rocket Atlas SLV-3C Centaur-D
Launch site Cape Canaveral LC-36B
End of mission
Last contact January 1973 (1973-02)
Orbital parameters
Reference system Geocentric
Regime Low Earth
Perigee 768 kilometres (477 mi)
Apogee 777 kilometres (483 mi)
Inclination 35.0 degrees
Period 100.30 minutes
Epoch 6 January 1969[1]

The Orbiting Astronomical Observatory 2 (OAO-2, nicknamed Stargazer) was a space observatory 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.[2]

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 Institute since 1973.[8]

The Wisconsin Experiment Package had eleven different telescopes for ultraviolet observations.[9] For example, there was a photoelectric photometer fed by a 16-inch (40.64 cm) telescope with a six-position filter wheel.[9] WEP observed over 1200 targets in ultraviolet light before the mission ended in early 1973.[4]

See also[edit]


  1. ^ McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Retrieved 12 October 2013. 
  2. ^ a b c Joseph A. Angelo – Spacecraft for Astronomy (2009) – Page 20 (Google Books)
  3. ^ Gunter – OAO-2
  4. ^ a b c d Orbiting Astronomical Observatory OAO-2
  5. ^ a b c d High-Resolution Telescopes
  6. ^ "Detector, Uvicon, Celescope". National Air and Space Museum. 2016-11-24. Retrieved 2018-01-24. 
  7. ^ [1]
  8. ^ "Detector, Uvicon, Celescope". National Air and Space Museum. 2016-11-24. Retrieved 2018-01-24. 
  9. ^ a b Wisconsin Experiment Package

External links[edit]