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| term | definition | link | ||
|---|---|---|---|---|
| Earth limb / Earth's limb | The Earth is a bright emitter of gamma rays, due to cosmic rays interacting with the atmosphere. | |||
| EBL | (Extragalactic Background Light). When used in gamma-ray astrophysics, EBL usually means the infrared-optical-ultraviolet light that fills intergalactic space, coming from all the stars that ever existed. Gamma rays can be absorbed by the EBL through the process of photon-photon pair production, in which a high-energy gamma ray collides with a low-energy IR-optical-UV photon to produce an electron-positron particle pair. | |||
| EDISP | (energy dispersion) The energy dispersion is a measure of how accurately we can reconstruct the energy of a photon from the energy it deposits in the LAT calorimeter. The energy dispersion is a part of the LAT Instrument Response Functions (IRFs), and information on the energy dispersion is automatically taken into account in the Science Tools for standard LAT analysis. | Cicerone | ||
| effective area | The number of photons detected divided by the source flux. The LAT effective area is a function of photon energy and inclination angle. | |||
| EPO (group) | (Education and Public Outreach) | EPO group link | ||
| event | An "event" is a catch-all name for "things that the LAT detects" (although sometimes it is used specifically to mean photons). In practice, these are either photons or cosmic rays. | |||
| event class | Events that are detected by the LAT are sorted into different classes based on how confident we are that the event is a photon. | Cicerone | ||
| Evo | Video conferencing software that has now been superseded by SeeVogh. | |||
| exposure |
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| term | definition | link |
|---|---|---|
| Pass #, version # | ||
| Pgwave | ||
| phi | ||
| pipeline | ||
| pointed observations | more info | |
| pole pointing | ||
| PSF | (point-spread function) When the LAT detects a photon, what actually happens is that the components of the LAT (tracker, calorimeter, ACD) register "hits" from the charged particles that the photon converts into. The PSF is a measure of how accurately we can reconstruct a photon based on the measurements of the charged particles' trajectories. The PSF of the LAT depends on both the original photon's energy and inclination angle. This is part of the set of LAT Instrument Response Functions (IRFs), and is automatically taken into account by the Science Tools. | Cicerone |
| PSR | (pulsar) | Pulsar group page |
| PWN | (pulsar wind nebula) |
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