A2SPECBACK ivo://nasa.heasarc/a2specback NASA/GSFC HEASARC HEASARC 2026-08-14 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Spectrum The A2 experiment was flown on the HEAO-1 satellite, between August, 1977 until January 1979. The experiment consisted of six multi-layer multi-anode collimated gas proportional counters. These were two LEDs (Low Energy Detectors), a MED (Medium Energy Detector), and three HEDs (High Energy Detectors). The first 6-months of mission were dedicated to an all-sky scan after which a pointing phase started. This database table accesses all the background files available at HEASARC obtained from the A2 MED (small and large field of view) and HEDs (1 and 3 small and large filed of view) detectors during the pointed phase. This is a service provided by NASA HEASARC . https://heasarc.gsfc.nasa.gov/W3Browse/all/a2specback.html Archive Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=a2specback& GET text/xml 180 99999 true 102.3914601 -80.1519281 1 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=a2specback GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_a2specback&Action=More+Options&Action=Parameter+Search&ConeAdd=1 HEAO1 1 X-ray public a2specback HEAO 1 A2 Spectra Background name Object Name meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable start_time Date and Time of Observation Start (MJD format) mjd time.start;obs double nullable count_rate Count Rate ct/s phot.count;em.X-ray.medium float nullable count_rate_error Count Rate Error ct/s stat.error;phot.count;em.X-ray.medium float nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable stop_date Date and Time of Observation Stop (DD/MM/YY HH:MM:SS) time.end;obs char nullable exposure Exposure Time (seconds) s time.duration;obs.exposure float nullable lii Galactic Longitude degree pos.galactic.lon double nullable filename File Name meta.id;meta.file char nullable stop_time Date and Time of Observation Stop (MJD format) mjd time.end;obs double nullable start_date Date and Time of Observation Start (DD/MM/YY HH:MM:SS) time.start;obs char nullable bii Galactic Latitude degree pos.galactic.lat double nullable rspfile Response Matrix File Name meta.id;meta.file char nullable