The UCSD/MIT Hard X-Ray and Low-Energy Gamma-Ray Instrument, A4, was flown on the HEAO 1 satellite, between August 1977 until January 1979. The experiment consisted of a collection of collimated sodium iodide scintillators, two of which the Low Energy detectors (LED, LED-3 and LED-6), were optimized for the lower energy part of the hard X-ray range between 13 to 180 keV. The first 6-months of mission were dedicated to an all-sky scan after which a pointing phase started. In pointing mode the A4-LED instrument look axis was kept in a 1 deg dead band centered on the target position. Instead in the "ping-pong" mode the look axis was regularly alternated with a secondary target a few degrees away, usually for background determination. This database table accesses the spectra (and associated files) obtained from the A4-LED detectors in the ping-pong mode. This is a service provided by NASA HEASARC .
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 .
The HEAO 1 A-1 X-Ray Source Catalog contains information about X-ray sources detected with the NRL Large Area Sky Survey Experiment (also referred to as the A-1 Experiment) flown aboard the HEAO-1 satellite. The catalog represents results from the first six months of data from HEAO-1, during which time a scan of the entire sky was completed. Positions and intensities for 842 sources are listed, with a limiting flux of 250 nanoJanskies (nJy) at 5 keV, or about 0.25 Uhuru flux units (UFU). The catalog is more than 90% complete at a flux level equivalent to 1.5 microJanskies (µJy) at 5 keV, for a Crab-like spectrum. The A-1 catalog has been cross-referenced with published literature. Identifications based on coincidence in position have been proposed for some of the sources for which previous work has established no firm identification. Half of the sources remained unidentified at the time of catalog publication (1984). The A3 database contains a list of 654 optical objects identified with A-1 error boxes. Minor structural changes were made to this database table and the documentation was revised by the HEASARC in July 2004. The basic content of the database table was unchanged, however. This is a service provided by NASA HEASARC .
This section describes the "class" parameter, which is included in many tables in the HEASARC database. It can be used to select objects according to their classifications. Each object is assigned a four digit numeric code to represent its object classification. The first digit describes the global classification (e.g., AGN or star). The following digits assign further classifications or properties such as spectral type, or type of AGN. Each sub-class is chosen to contain a unique set of properties. For example, all normal (non-degenerate) stars have the first digit set to 2. The second digit for stars indicates the spectral type (O, B, etc.), the third digit the numerical sub-type, and the last digit the luminosity class; thus, a G5V star will have the class code of 2555. All stars later (cooler) than F0 have a "class" number between 2400 and 2999. As another example, all AGN have class codes that lie between 7000 and 7999; a search by class for AGN would thus be made by doing a search of the class parameter with the range set from 7000 to 7999. It should be emphasized that the class assignments of the same source found in different databases may not always be identical, and, for any given database, the class codes may not always be present, correct, or complete: see the database help for the particular database in question to determine how the class codes were constructed. ALWAYS USE THE CLASS CODES WITH THESE CAVEATS IN MIND. This is a service provided by NASA HEASARC .
The Henry Draper (HD) Catalog (Cannon and Pickering 1918 - 1924, Ann. Astron. Obs. Harvard College 91 - 99) and its first extension, the Henry Draper Extension (HDE) Catalog (Cannon 1934, Ann. Astron. Obs. Harvard College 100, 1 - 6), provided spectral classification and rough positions for 272,150 stars and has been widely made use of by the astronomical community for over half a century. A second extension of the HD Catalog, the so-called Henry Draper Extension Charts (HDEC), subsequently extended this spectral classification to fainter magnitudes (Cannon 1937, Ann. Astron. Obs. Harvard College 105, 1; Cannon and Mayall 1949, Ann. Astron. Obs. Harvard College 112), thus adding nearly another 87,000 stars with derived spectral types. The information in the HDEC was published in the form of charts rather than tables like the HD and HDE Catalogs, and consequently has been barely utiized by modern astronomers. In the 1990's, after a pilot project of Roeser et al. (1991, Astr. Ap. Suppl., 88, 277) had demonstrated that it seemed feasible to `revive' the HDEC data, they were converted into a catalog of accurate astrometric parameters along with magnitudes and spectral types by Nesterov et al. (1995, Astr. Ap. Suppl., 110, 367), who used measurements of Cartesian coordinates of stars in the charts and the positions in the Astrographic Catalog (AC) for subsequent cross-identification. The Nesterov et al. (1991) reference should be consulted for the full details on the procedures used to create this HDEC catalog. The HDEC catalog contains information on 86,933 stars, comprising accurate (0.5 arcseconds error) positions, (for more than 96 per cent of them) proper motions with a typical accuracy of 5.5 milliarcseconds (mas) per year, and the original spectral classifications. The current database contains the main portion of the catalog. An additional set of information, primarily comprising HD entries with cross-identifications with known or suspected variable stars, was included in the A.J. Cannon Memorial Volume (Cannon and Mayall 1949). This list was extended by Nesterov et al. (1991) to more than 500 identifications with variable stars. This latter expanded list, together with a list of entries which have uncertain identifications, is not included in the HEASARC version of this catalog, but it is available on the HEASARC website in the directory <a href="/FTP/heasarc/dbase/misc_files/hdec/">/FTP/heasarc/dbase/misc_files/hdec/</a> as the file <a href="/FTP/heasarc/dbase/misc_files/hdec/hdec.remarks">hdec.remarks</a>. If the parameter "remarks" is set to "R" for an entry in the HDEC catalog, this means that there is a remark about that particular star in the above file. This database was created by the HEASARC in April 1998 based on the machine-readable ADC/<a href="https://cdsarc.cds.unistra.fr/ftp/cats/III/182">CDS Catalog III/182</a>. This is a service provided by NASA HEASARC .
This database table contains the Third Catalog of Emission-Line Stars of the Orion Population (Herbig and Bell (1988)) which lists 735 pre-main sequence stars, members of the Orion Population, that have been observed with slit spectrographs or at equivalent resolution. It is intended to replace the Second Catalog of Herbig and Rao (1972). It gives accurate coordinates (many determined especially for this Catalog); light ranges for known variables; UBVRI data near maximum light; references to ultraviolet, X-ray, and radio observations, and to light curves; value of v sin i and the radial velocity when known; spectral type; equivalent width of the H-alpha emission line; references to spectral reproductions or scans and spectroscopic studies and to identification charts; and a classification (as a T Tau star, FU Ori object, etc.). This is a service provided by NASA HEASARC .
The Herschel Space Observatory (Herschel) is an ESA (European Space Agency) project with instruments funded by ESA member states. It was operated from May 2009 till April 2013, offering unprecedented observational capabilities in the far-infrared and sub-millimeter spectral range (55-671 microns [um]). Herschel carried a 3.5m diameter passively cooled Cassegrain telescope, which was the largest of its kind and utilizes a novel silicon carbide technology. The science payload comprised three instruments: two direct detection cameras/medium resolution spectrometers, the Photodetector Array Camera and Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE), and a very high-resolution heterodyne spectrometer, the Heterodyne Instrument for the Far Infrared or HIFI, whose focal plane units were housed inside a superfluid helium cryostat. PACS comprised two mutually exclusive sub-instruments: a bolometric camera designed to perform photometry in three spectral bands (70, 100 and 160 um) and an integral field unit grating spectrometer operating over the spectral range from 57 to 210 um with a spectral resolution ranging from 1000 to 5000. SPIRE comprised a three-band photometer, operating in spectral bands centered on 250, 350 and 500 um, and an imaging Fourier-Transform Spectrometer (FTS), which provided low resolution spectra over the 195-670 um band. Both instruments used germanium bolometers operating at 0.3 K and coupled to the telescope with hexagonally conical feedhorns. The photometer and the spectrometer were not designed to operate simultaneously. HIFI was designed to obtain spectra with very high resolution (up to 10<sup>7</sup>) in the far-infrared and sub-millimeter wavelengths not directly observable by ground-based telescopes. The HIFI instrument was an heterodyne receiver which provided spectroscopy in the continuous frequency range 480-1250 GHz (240-625 microns) and in the frequency range 1410-1910 GHz (157-213 microns). Herschel had two Announcement of Opportunities (AOs) for Open Time (OT) observations. The first in-flight AO for Open Time (OT1) was opened on 20 May 2010, with a deadline of 22 July 2010. For OT1, 241 observing programs were accepted and the total allocated observing time amounts to 6576.9 hours. The second in-flight AO for Open Time (OT2) was opened on 9 June 2011, with a deadline of 15 September 2011. There were parallel AOs for Guaranteed Time observations, GT1 and GT2, with separate deadlines. The Announcement of Opportunity (AO) for Herschel Key Programs (KP) was issued on 1 February 2007, with separate deadlines for guaranteed time (GT) and open time (OT) proposals. The whole Key Program AO process has now been completed, and by coincidence there were exactly the same number of KP GT and OT programs, in both cases 21 programs were awarded observing time. Taken together, these 42 observing programs contained 11,650 astronomical observation requests or AORs (AORs are the primary units of Herschel observing time and are effectively the Herschel 'observation units'). The total allocated observing time for these programs was 11,257.7 hours, corresponding to approximately 57% of the nominally available Herschel routine mission science time. Herschel successfully made over 37,000 scientific observations before its helium cryogen was exhausted. The HSA is available at the Herschel Science Centre at <a href="http://herschel.esac.esa.int/Science_Archive.shtml">http://herschel.esac.esa.int/Science_Archive.shtml</a>, the Herschel help desk is at <a href="http://herschel.esac.esa.int/esupport/">http://herschel.esac.esa.int/esupport/</a>, the Herschel User Provided Data Products are available at <a href="http://herschel.esac.esa.int/UserProvidedDataProducts.shtml">http://herschel.esac.esa.int/UserProvidedDataProducts.shtml</a>, the Herschel Postcard Server is at <a href="http://archives.esac.esa.int/hsa/aio/doc/postcardGallery.html">http://archives.esac.esa.int/hsa/aio/doc/postcardGallery.html</a>, and the Herschel Observation Log is at<a href="http://herschel.esac.esa.int/logrepgen/observationlist.do">http://herschel.esac.esa.int/logrepgen/observationlist.do</a> This table was created by the HEASARC in October 2013 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/VI/139">CDS Catalog VI/139</a> file herschel.dat. This is a service provided by NASA HEASARC .
Herschel Stripe 82 Survey (HerS) Point Source Catalog
Short Name:
HERS82CAT
Date:
07 Mar 2025
Publisher:
NASA/GSFC HEASARC
Description:
This study presents the first set of maps and band-merged catalog from the Herschel Stripe 82 Survey (HerS). Observations at 250, 350, and 500 micron (µm) were taken with the Spectral and Photometric Imaging Receiver (SPIRE) instrument onboard the Herschel Space Observatory. HerS covers 79 square degrees along the SDSS Stripe 82 to an average depth of 13.0, 12.9, and 14.8 mJy beam<sup>-1</sup> (including confusion) at 250, 350, and 500 um, respectively. HerS was designed to measure correlations with external tracers of the dark matter density field, either point-like (i.e., galaxies selected from radio to X-ray) or extended (i.e., clusters and gravitational lensing), in order to measure the bias and redshift distribution of intensities of infrared-emitting dusty star-forming galaxies and active galactic nuclei. By locating HerS in Stripe 82, the authors maximize the overlap with available and upcoming cosmological surveys. The band-merged catalog contains 3.3 x 10<sup>4</sup> sources detected at a significance of >~ 3 sigma (including confusion noise). The maps and catalog are available at <a href="http://www.astro.caltech.edu/hers/">http://www.astro.caltech.edu/hers/</a>. This table contains the first HerS band-merged point source catalog based on observations covering 79 deg<sup>2</sup> in the equatorial Stripe 82, spanning 13 to 37 degrees (0<sup>h</sup> 54<sup>m</sup> to 2<sup>h</sup> 24<sup>m</sup> ) in RA, and -2 to +2 degrees in Declination. The SPIRE beams are 18.1, 25.2 and 36.6 arcseconds at 250, 350 and 500 um, respectively. The band-merged catalog was constructed, after filtering, with DESPHOT (Roseboom et al. 2010, MNRAS, 409, 48), using 250-um sources (extracted with STARFINDER: Diolaiti et al. 2000, A&AS, 147, 335) as positional priors. The authors included sources with S/N greater than 3, whose completeness is estimated to be 50% (see Figure 7 of the reference paper), with a false detection rate less than 1%, and which had reasonable residuals (i.e., chi<sup>2</sup> < 10). Next, they identified obviously extended sources - 24 in total - where their extended nature resulted in them being broken up into multiple components by the filter, and removed them. This results in a catalog with 32,815 sources at 250 um, of which 13,300 and 3,276 have similarly defined 3-sigma detections at 350 and 500 um, respectively. The authors expect a false positive rate of 1.2 +/- 0.2 deg<sup>-2</sup> : thus, across the 79 deg<sup>2</sup> of HerS, they expect 96 +/- 16 spurious sources. The following local extended sources were removed: <pre> Name, RA, DEC NGC 0493,20.537458,0.945361 UGC 00890,20.283333,1.373333 UGC 00892,20.319166,-0.544491 NGC 0428,18.232125,0.981556 NGC 0799,30.551407,-0.100629 NGC 0800,30.549358,-0.130432 NGC 0450,18.876840,-0.860973 NGC 0497,20.599064,-0.875207 NGC 0867,34.269910,1.244202 UGC 01725,33.607833,1.469833 NGC 0570,22.244325,-0.948996 UGC 00711,17.153750,1.641667 UGC 00726,17.489833,-1.749694 NGC 0550,21.677292,2.022361 NGC 0585,22.9255833,-0.9333056 UGC 01123,23.533209,-1.032286 2MASX J01434929-0048547,25.955091,-0.815256 NGC 0856,33.409831,-0.717287 UGC 01698,33.082019,-0.811513 CGCG 385-007,17.256708,1.378194 UGC 00790,18.657792,1.180167 2MFGC 01002,19.930083,1.630778 2MFGC 00979,19.642792,1.747889 UGC 00847,19.768317,-0.138572 </pre> This database table was created by the HEASARC in March 2014 based on a FITS file (v2.0, uploaded Nov 18, 2013, of hers.catalogue_3sig250_no_extended.fits) containing the catalog which was obtained from the HerS web site, viz., <a href="http://www.astro.caltech.edu/hers/Catalogs.html">http://www.astro.caltech.edu/hers/Catalogs.html</a>. Some of the values for the name parameter in the HEASARC's implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .
HESS (High Energy Stereoscopic System) Source Catalog
Short Name:
HESSCAT
Date:
07 Mar 2025
Publisher:
NASA/GSFC HEASARC
Description:
H.E.S.S. is a system of Imaging Atmospheric Cherenkov Telescopes for the investigation of cosmic gamma rays in the 100 GeV energy range. The name H.E.S.S. stands for High Energy Stereoscopic System, and should also remind us of Victor Hess, who received in 1936 the Nobel Prize in Physics for his discovery of cosmic radiation. The instrument allows us to explore gamma-ray sources with intensities at a level of a few thousandth parts of the flux of the Crab nebula. H.E.S.S. is located in Namibia, near the Gamsberg, an area well known for its excellent optical quality. The first of the four telescopes of Phase I of the H.E.S.S. project went into operation in Summer 2002; all four were operational in December 2003, and were officially inaugurated on September 28, 2004. In recognition of its scientific results, H.E.S.S. was awarded the 2006 Descartes Prize for Research of the European Commission. This database table, first created in April 2008, contains the H.E.S.S. source list created by Dr. W. Hofmann and is based on the HTML table at <a href="http://www.mpi-hd.mpg.de/hfm/HESS/public/HESS_catalog.htm">http://www.mpi-hd.mpg.de/hfm/HESS/public/HESS_catalog.htm</a>. The latter table is updated regularly and this HEASARC table will be updated within one week of any updates. This is a service provided by NASA HEASARC .
HETE-2 (the High Energy Transient Explorer) is an international mission designed to help unravel the mystery of Gamma-Ray Bursts (GRBs). The primary goal of HETE-2 is to determine the origin and nature of cosmic gamma-ray bursts (GRBs) by simultaneous observation of soft and medium X-rays and gamma-rays to provide precise localization of GRBs and identification of counterparts to these explosions. HETE-2 carries three science instruments: a set of wide-field gamma-ray spectrometers (FREGATE), a wide-field X-ray monitor (WXM, and a set of soft X-ray cameras (SXC) HETE-2 was launched on October 9, 2000, and declared fully operational on February 6, 2001. The contents of this HEASARC database table are based on the burst summary web pages created at MIT at the <a href="http://space.mit.edu/HETE/Bursts/">http://space.mit.edu/HETE/Bursts/</a>. The HEASARC table will be updated on a twice-per-week basis shortly after whenever the MIT web pages are updated. This is a service provided by NASA HEASARC .
