FERMI2FAVS - Fermi All-Sky Variability Analysis Second Catalog of Flaring Gamma-Ray Sources

Overview

The Fermi All-sky Variability Analysis (FAVA) is an analysis technique that searches for flaring sources in data collected by the Large Area Telescope (LAT) onboard NASA's Fermi Gamma-ray Space Telescope. It uses a photometric approach to blindly search for flares over the entire sky, and a likelihood analysis to precisely locate them and to measure their spectra.

This catalog contains the flares and sources detected by running FAVA over the first 7.4 years of Fermi mission, from Modified Julian Date (MJD) 54682 (2008-08-04) to 57391 (2016-01-04). The analysis has been run in weekly time bins and in two independent energy bands, 100-800 MeV and 0.8-300 GeV. The detection threshold applied to the catalog flares is equivalent to 6 sigma (pre trials).

The sources in the 2FAV are identified as clusters of flares. Their position and the corresponding error are derived from a weighted average of the best localized flares in the cluster. Likely gamma-ray counterparts, based on positional coincidence, are provided for the sources.

Catalog Bibcode

2017ApJ...846...34A

References

A full description of the catalog is given by the FAVA team in "The Fermi All-sky Variability Analysis". Additional information for which is available at http://fermi.gsfc.nasa.gov/ssc/data/access/lat/fava_catalog/.

Provenance

This database table was first ingested by the HEASARC in July 2017 using electronic data obtained from the Fermi Science Support Center (FSSC). That data is available at http://fermi.gsfc.nasa.gov/ssc/data/access/lat/fava_catalog/.

Parameters

Source_Number
The sequential identification number for each source in the catalog.

Name
The name of the 2FAV source, constructed as 2FAV JHHMM+DD.d[f] where HHMM expresses the Right Ascension (J2000) of the source in hours and minutes, and DD.d is the declination in degrees, truncated to the first decimal place. An 'f' is used to flag then source name in case it has been found significant by the photometric analysis, but not by the likelihood. The worst positional precision of the former suggest caution with this source.

RA
The Right Ascension of the source in the selected equinox. This was given in J2000 decimal degree coordinates to a precision of 10^-2 degrees in the original table.

Dec
The Declination of the source in the selected equinox. This was given in J2000 decimal degree coordinates to a precision of 10^-2 degrees in the original table.

LII
The Galactic Longitude of the source in degrees. This was given in decimal degree coordinates to a precision of 10^-2 degrees in the original table.

BII
The Galactic Latitude of the source in degrees. This was given in decimal degree coordinates to a precision of 10^-2 degrees in the original table.

Total_Flares
The total number of flares associated with the source (saturated flares are excluded).

High_Energy_Flares
The number of high-energy (0.8-300 GeV) flares associated with the source (saturated flares are excluded).

Negative_Flares
The number of negative flares associated with the source (saturated flares are excluded).

Error_Radius
The estimate of the 95% containment radius in degrees.

Search_Radius
The search radius used to look for counterparts. Defined as R_s = r_99% + 0.1 deg (systematics).

Gamma_Ctrprt_Name
The likely gamma-ray counterpart (based on positional coincidence).

Gamma_Ctrprt_Var_Flag
This parameter contains 'N' if the sourcés variability index in the 2FGL or 3FGL catalog is below the threshold to be considered variable at 99% probability or 'Y' otherwise.

Other_Ctrprt_Name
The likely counterpart at other wavelengths (as published in the considered catalogs).

Source_Type
The source type of the likely counterpart following the 3FGL scheme for class names.

Telegram_Number
The number for the Astronomer's Telegram alert associated with the source.

Contact Person

Questions regarding the FERMI2FAVS database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: Tuesday, 02-Jun-2020 14:46:26 EDT