SDS (Solar Disk Sextant)

The Solar Disk Sextant (SDS) is a balloon-borne instrument whose objective is to measure the solar diameter, at different orientations, as a function of time. Results include the solar oblateness, the oscillation spectrum for use in helioseismology, and the rate of the secular variation of the solar diameter. The required instrumentation precision (a few milliarcsec) is attained by means of an objective beam splitting wedge which produces multiples solar images through consecutive reflections.

Balloon launched on: 9/30/1992 at 12:58 utc
Launch site: Scientific Flight Balloon Facility, Fort Sumner, (NM), US  
Balloon launched by: National Scientific Balloon Facility (NSBF)
Balloon manufacturer/size/composition: Zero Pressure Balloon N40I-8/8T-11.62
Balloon serial number: R11.62-1-113
Flight identification number: 345N
End of flight (L for landing time, W for last contact, otherwise termination time): 9/30/1992 at 23:05 utc
Balloon flight duration (F: time at float only, otherwise total flight time in d:days / h:hours or m:minutes - ): ~ 10 h
Landing site: 13 miles SW of Quanah, Texas, US

• Development of a System for Accurate Forecasting of Solar Activity Annual rept. 15 Oct 91-14 Oct 92
• NASA Balloon Flights (1989-1998) in NASA Historical Data Book, Vol. VII: NASA Launch Systems, Space Transportation, Human Spaceflight, and Space Science, 1989-1998
• Results of the September 30, 1992 Balloon Flight of the Solar Disk Sextant Bulletin of the American Astronomical Society, Vol. 25, p.1225
• The solar diameter and oblateness measured by the solar disk sextant on the 1992 September 30 balloon flight Astrophysical Journal, Part 1, vol. 427, no. 2, p. 1048-1052
• Variation of the Diameter of the Sun as Measured by the Solar Disk Sextant (SDS) Monthly Notices of the Royal Astronomical Society, Volume 436, Issue 3, 11 December 2013, Pages 2151-2169