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Wisconsin Experiment Package

NSSDCA ID: 1968-110A-02

Mission Name: OAO 2
Principal Investigator:Dr. Arthur D. Code


This Wisconsin equipment package contained seven telescopes designed to make spectrophotometric measurements of selected celestial objects in the ultraviolet longward of 1050 A; a set of four stellar photoelectric photometers located behind 8-in. telescopes; a nebular photoelectric photometer located at the prime focus of a 16-in. telescope; and a set of two objective grating spectrometers. The stellar photometers were each located behind a filter wheel containing three filter passbands, a calibration source, and a dark slide. The filter passbands ranged from 1180 to 1370 A with effective wavelength 1330 A, and from 3810 to 4670 A with effective wavelength 4250 A. The filter passbands were arranged to provide redundant coverage so that the telescope responses could be cross-correlated. Two field stops were provided with angular diameters of 2 arc-min and 10 arc-min. Photons were detected by photomultipliers. These photomultipliers drove pulse counters and dc amplifiers, thus providing redundant output. Unfortunately, the analog channel of stellar photometer 4 failed shortly after launch and provided no useful data. The filters experienced some degradation in orbit. Corrections to be applied to the stellar photometer data are becoming available. The nebular photometer was located behind a six-position filter wheel providing passbands from 1930 to 2230 A (effective wavelength 2130 A) to 3050 to 3570 A (effective wavelength 3330 A,) as well as a calibration slide and a dark slide. A pulse counter and dc amplifier similar to those used with the stellar photometers were used with this photometer meter. About 2-1/2 months after launch, a failure left the calibration source permanently in place, and no further data resulted from this detector. Spectrometer 1 covered the wavelength range from 1800 to 3800 A in 100 steps with resolutions of 20 or 200 A (switchable). The slit width of 20 A corresponded to 2 arc-min projected on the sky, and the slit height corresponded to 8 arc-min. Spectrometer 2 covered the wavelength range from 1050 to 2000 A in 100 steps with resolutions of 10 or 100 A. The slit width of 10 A corresponded to 2 arc-min projected onto the sky, and the slit height corresponded to 8 arc-min. Aside from the failures of the nebular photometer, the analog channel of stellar photometer 4, and the degradation of the filters, the instrument operated normally from launch to spacecraft shutoff in February 1973. For more details, see A. D. Code et al., Ap. J., v. 161, p. 377, 1970.

Alternate Names

  • High Resolution (Spatial) All Sky Broad Band UV Scanner
  • OAO2/WisconsinExperimentPackage

Funding Agency

  • NASA-Office of Space Science Applications (United States)


  • Astronomy: Visible
  • Astronomy: Ultraviolet

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Dr. Robert L. Davis, M.D.Other InvestigatorSmithsonian Astrophysical Observatory
Dr. Arthur D. CodePrincipal InvestigatorUniversity of
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