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| term | definition | links |
|---|---|---|
| ACD | (Anti-Coincidence Detector) The ACD is the collection of scintillating tiles that detect charged particles, and is crucial to background rejection. The ACD covers the tracker (the part of the LAT that converts gamma rays into electron-positron pairs and then tracks these pairs' trajectories). Charged particles will also register as signals in the tracker, so the ACD is used to determine if a signal is actually a charged particle and not a gamma ray. If an ACD tile has a "hit" (detects a charged particle) that lines up with a signal, then that fact is used to "veto" the signal (i.e., declare that it's not a gamma ray). | |
| Acceptance | Defined as the effective area integrated over the solid angle (units: m^2 sr). | LAT performance page |
| AGN (group) | (Active Galactic Nuclei) | AGN group page |
| ARR | (Autonomous Repoint Request) | |
| ASP | ||
| ATel | (Astronomer's Telegram) Multiwavelength, web-based short-notice publication system for reporting and commenting on new astronomical observations. | |
| ATS | Absolute Time Sequence. A series of spacecraft and/or instrument commands that are loaded on the Fermi spacecraft. | |
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| term | definition | link |
|---|---|---|
| dec | (declination) | |
| diffuse (group) | Diffuse group page | |
| diffuse (event class) | In previous versions of the LAT data, the diffuse event class was the event class with the most stringent cuts on background. However, the "diffuse" name is no longer used. | |
| DM (group) | (Dark Matter) | DM group link |
| DQM | (Data Quality Monitor) | |
| ds9 | (Deep Space 9 (seriously)) ds9 is a piece of software that is used for data visualization and imaging. For instance, someone analyzing Fermi data might use ds9 to look at a counts map (a map of where the photons that Fermi observed came from). | http://ds9.si.edu/site/Home.html |
| DRP | ||
| dSph | (dwarf spheroidal galaxy) |
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| term | definition | link |
|---|---|---|
| Pass #, version # | ||
| Pgwave | ||
| phi | ||
| pipeline | ||
| pointed observations | ||
| pole pointing | ||
| PSF | (point-spread function) | |
| PSR | (pulsar) | Pulsar group page |
| PWN | (pulsar wind nebula) | |
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