- ID:
- ivo://nasa.heasarc/comptel
- Title:
- CGRO/COMPTEL Low-Level Data and Maps
- Short Name:
- COMPTEL
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- COMPTEL is both the name of the Imaging Compton Telescope on the Compton Gamma Ray Observatory (CGRO) and the name of this HEASARC database table which allows the user to select low-level data and maps produced by this instrument. Much more information on the COMPTEL instrument, data products, and data analysis techniques can be obtained from the Compton Observatory Science Support Center (COSSC) web site at <pre> <a href="https://heasarc.gsfc.nasa.gov/docs/cgro/">https://heasarc.gsfc.nasa.gov/docs/cgro/</a> </pre> and from the article in Legacy No. 7 on the HEASARC CGRO Data Archive <pre> <a href="https://heasarc.gsfc.nasa.gov/docs/journal/cgro7.html">https://heasarc.gsfc.nasa.gov/docs/journal/cgro7.html</a> </pre> Interactions in COMPTEL occur in a two stage process: First, a Compton collision occurs in one of seven (low-Z) liquid scintillators and is usually then completely absorbed in one of fourteen (high-Z) NaI(Tl) scintillators. The unusual aspect of this detector is that the location of the gamma-ray on the sky is given by an annulus and not a point. The correlation of many events enables the localization of point sources or the creation of sky maps. Time-of-flight measurements, pulse shape discrimination and anti-coincidence shields are used to reject background events. COMPTEL has a wide field of view (about 1 steradian, equivalent to a FWHM of about 40 degrees), an angular resolution under optimal conditions of about 1 degree, and an energy resolution that ranges from 5-10% at 1 MeV. During Phase 1 of the CGRO mission, COMPTEL completed the first all-sky survey in the energy range of 0.75-30 MeV (in four energy bands). In addition, COMPTEL can measure energy spectra of solar flares or bright cosmic gamma-ray bursts between 0.1-10 MeV, and neutrons from solar flares. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/egretdata
- Title:
- CGRO/EGRET Photon Lists and Maps
- Short Name:
- GRO/EGRET
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Energetic Gamma-Ray Experiment Telescope (EGRET), which operated from 1991-April until 2000-May, was sensitive to photons in the energy range from about 30 MeV to over 20 GeV, the highest energies accessible by the CGRO instruments, and, like COMPTEL, was an imaging instrument. This catalog includes photon lists in qvp files, with one file for each EGRET viewing period. Photons which pass an energy-dependent cut on zenith angle (to exclude earth-albedo gamma rays) are processed into maps of photon counts for a standard set of energy ranges. Exposure and intensity (counts divided by exposure) maps are generated for each counts map. The counts maps typically include photons detected up to 40 degrees from the instrument axis. Most analysis has been done using data within 30 degrees of the instrument axis, where the point-spread function is narrower and the effective area greater than further off axis. All EGRET data files in the archive are the final versions, produced after the end of the mission. More detailed information about EGRET, EGRET data, and EGRET data analysis software can be found at: <pre> <a href="https://heasarc.gsfc.nasa.gov/docs/cgro/egret/egret_doc.html">https://heasarc.gsfc.nasa.gov/docs/cgro/egret/egret_doc.html</a> </pre> The data contained in this database table was supplied by the CGRO Science Support Center. The contents this table was last updated in May 2001. Galactic coordinates were added to the table by the HEASARC in August 2005. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/osse
- Title:
- CGRO/OSSE Observations
- Short Name:
- OSSE
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table is based on the set of OSSE observation data products available at the HEASARC. The Oriented Scintillation Spectrometer Experiment (OSSE) is one of four experiments on NASA's Compton Gamma Ray Observatory (CGRO) satellite. OSSE was designed to undertake comprehensive gamma-ray observations of astrophysical sources in the 0.05-10 MeV energy range. The instrument also had secondary capabilities for gamma-ray and neutron observations above 10 MeV that are of particular value for solar flare studies. This database table was last updated in August 2005. Some duplicate entries in the table were removed in June 2019. The data in this table was supplied by the CGRO Science Support Center. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/cgrotl
- Title:
- CGRO Timeline
- Short Name:
- CGROTL
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Compton Gamma-Ray Observatory (CGRO) was the second of NASA's Great Observatories. It was launched on April 5, 1991, from Space Shuttle Atlantis. It operated successfully for 9 years, and then was safely de-orbited and re-entered the Earth's atmosphere on June 4, 2000. Compton had four instruments that covered an unprecedented six decades of the electromagnetic spectrum, from 30 keV to 30 GeV. In order of increasing spectral energy coverage, these instruments were the Burst And Transient Source Experiment (BATSE), the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (CompTel), and the Energetic Gamma Ray Experiment Telescope (EGRET). BATSE viewed the full sky, as a transient monitor and is thus not included in this database table of pointed telescope observations. Also, EGRET and CompTel had wide fields of view, about 30 degrees, and, as such, viewed multiple targets per X-axis pointing. OSSE could be slewed (about one axis) independently from the spacecraft, so it typically viewed 2 targets per spacecraft Z-axis orientation, or "viewing period." Viewing periods were typically two weeks long. This database table contains the CGRO observations for Cycles 1 through 9. The Cycle 1 observations for EGRET and COMPTEL were part of the All-Sky Survey with no defined targets. This database table was last updated in November 2001. The information contained therein was provided by the Compton Observatory Science Support Center (COSSC). Galactic coordinates were added to the table by the HEASARC in August 2005. Duplicate entries in the table were removed in June 2019. This is a service provided by NASA HEASARC .
