Purpose of the flight and payload description
The BUSS experiment was designed to perform spectrophotometric measurements of the stars in the UV domain. The telescope was mounted on a biaxial pointer, and was controlled in elevation and azimuth by a boresighted startracker. Both the telescope-spectrometer and the pointer were designed and built . The telescope has a focal length of 300 cm and a diameter of 40 cm. It consisted of an f/3 primary mirror and a secondary mirror with magnification m = 2.5. By means of image motion compensation an ultimate tracking precision of a few seconds of arc is achieved. The secondary mirror is mounted in a biaxial flex-pivot gimbal system, and can be tilted by means of two small torque motors.
Near the focal plane a dichroic mirror reflects the ultraviolet radiation towards the spectrometer, and transmits the visible light towards a star position sensor, which provides the control signals for the torque motors.
The original payload was designed and built by Ball Brothers Research Corporation of Boulder, Colorado, in 1971. The payload is about 3.5 m in diameter by 2.5 m high and weighs 540 kg, excluding ballast. Crush pads are attached to the four legs of the lower section or gondola, and the roll cage supplies additional protection to the telescope.
Details of the balloon flight
Balloon launched on: 9/16/1976
Launch site: Columbia Scientific Balloon Facility, Palestine, Texas, US
Balloon launched by: National Scientific Balloon Facility (NSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon Raven - 600.000 m3 (15.00 microns)
Flight identification number: 985P
End of flight (L for landing time, W for last contact, otherwise termination time): 9/16/1976
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): F 11 h 5 m
Payload weight: 932.5 kg
- Balloon-borne ultraviolet stellar echelle spectrograph Applied Optics Vol. 17, Issue 4, pp. 604-613 (1978)
- Balloon-borne ultraviolet stellar spectrograph. I - Instrumentation and observation. II - Highlights of first observational results Astrophysical Journal, Part 1, vol. 230, June 1, 1979, p. 526-539
- Chromospheric models for ALTAIR (A7 IV-V) The Astrophysical Journal, Part 1, vol. 439, no. 2, p. 1011
- Evidence for a supersonic turbulent velocity gradient in the outer photosphere of the supergiant alpha Cygni (A2Ia) Astronomy and Astrophysics, vol. 141, no. 2, Dec. 1984, p. 304-308
- Interstellar absorption lines between 2000 and 3000 A in nearby stars observed with BUSS Astronomy and Astrophysics, vol. 157, no. 1, March 1986, p. 119-128
- Microturbulence in the upper photosphere of Alpha Persei (F5 Ib) derived from ultraviolet spectral observations Astronomy and Astrophysics, vol. 185, no. 1-2, Oct. 1987, p. 229-232
- National Scientific Balloon Facility Annual Report, FY 1977 National Center for Atmospheric Research, 1978
- The mid-ultraviolet spectrum of Epsilon Aurigae Astronomy and Astrophysics Supplement Series, vol. 50, Nov. 1982, p. 233-245
- The ultraviolet spectrum of Procyon. I - The atlas from 2030 to 2371 A Astrophysical Journal Supplement Series, vol. 61, Aug. 1986, p. 719
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