VERIMASTER - VERITAS Source Catalog

Overview

The Very Energetic Radiation Imaging Telescope Array System (VERITAS) is a major ground-based gamma-ray observatory operating at the Fred Lawrence Whipple Observatory (FLWO) in southern Arizona, USA. It is an array of four 12m optical telescopes for gamma-ray astronomy in the GeV - TeV energy range. VERITAS is an imaging air Cerenkov system. Gamma-rays from astrophysical sources create particle showers in the Earth's upper atmosphere that produce Cerenkov photons detected on the ground using the large optical telescopes. These telescopes are deployed such that they have the highest sensitivity in the VHE energy band (50 GeV - 50 TeV), with maximum sensitivity from 100 GeV to 10 TeV. The four telescope array is needed for stereoscopic observations that allow the reconstruction of the particle shower geometry, thus giving precise angular and energy resolution. This very high energy observatory, completed in 2007, effectively complements the Fermi Gamma-ray Space Telescope due to its large collection area as well as its higher energy bound and improved angular resolution.

VERITAS started four-telescope operations in 2007 and collects about 1100 hours of good-weather data per year. The VERITAS collaboration has published over 100 journal articles since 2008 reporting on gamma-ray observations of a large variety of objects: Galactic sources like supernova remnants, pulsar wind nebulae, and binary systems; extragalactic sources like star forming galaxies, dwarf-spheroidal galaxies, and highly-variable active galactic nuclei. Additional details are available at the VERITAS website.

The catalog lists the sources observed by VERITAS as of April 2022, including cross-matches with other gamma-ray observations and spectral fits. This catalog has associated high-level data products containing data from VERITAS publications.

Catalog Bibcode

2023RNAAS...7....6A

References

VTSCat: The VERITAS Catalog of Gamma-Ray Observations
    Acharyya, A., Adams, C. B., Archer, A., Bangale, P., Bartkoske,
    J. T., Batista, P., Benbow, W., Brill, A., Brose, R., Buckley, J. H.,
    Capasso, M., Christiansen, J. L., Chromey, A. J., Daniel, M. K.,
    Errando, M., Falcone, A., Farrell, K. A., Feng, Q., Finley, J. P.,
    Foote, G. M., Fortson, L., Furniss, A., Gallagher, G., Gent, A.,
    Giuri, C., Gueta, O., Hanlon, W. F., Hanna, D., Hassan, T.,
    Hervet, O., Hoang, J., Holder, J., Hughes, G., Humensky,
    T. B., Jin, W., Kaaret, P., Kertzman, M., Kieda, D., Kleiner,
    T. K., Korzoun, N., Krennrich, F., Kumar, S., Lang, M. J.,
    Lundy, M., Maier, G., McGrath, C. E., Millard, M. J.,
    Mooney, C. L., Moriarty, P., Mukherjee, R., Nieto, D.,
    Nievas-Rosillo, M., O'Brien, S., Ong, R. A., Otte, A. N.,
    Pandel, D., Park, N., Patel, S. R., Patel, S., Pfrang, K.,
    Pichel, A., Pohl, M., Prado, R. R., Pueschel, E., Quinn, J.,
    Ragan, K., Reynolds, P. T., Ribeiro, D., Richards, G. T.,
    Roache, E., Rovero, A. C., Rulten, C., Ryan, J. L., Sadeh, I.,
    Santander, M., Schlenstedt, S., Sembroski, G. H., Shang, R.,
    Splettstoesser, M., Stevenson, B., Tak, D., Vassiliev, V. V.,
    Wakely, S. P., Weinstein, A., Williams, D. A., Williamson, T. J.,
    Angelini, L., Basu-Zych, A., Sabol, E., and Smale, A.
    <Research Notes of the American Astronomical Society, 7, 6 (2023)>
    =2023RNAAS...7....6A

Provenance

This database table was ingested by the HEASARC in December 2022 and is based upon data files provided by the VERITAS Team. A minor correction to one entry in the catalog was made in April 2024.

High-level data products were collected from VERITAS publications. Data and fit results were extracted from the published papers or from internal VERITAS analysis results used to produce the published figures and tables. In many cases, spectral and light curve data were obtained by digitizing published figures. This process was led by Gernot Maier at DESY with contributions from many members of the VERITAS collaboration. The primary archive can be accessed on GitHub or downloaded via Zenodo (doi:10.5281/zenodo.6163391). Translation to formats suitable for the HEASARC was led by Philip Kaaret with assistance by Sameer Patel at the University of Iowa and by the HEASARC Team.

Data Products

This catalog has the following high-level data products associated with most entries:

The ver_*_lc.fits.gz files contain the published lightcurve data in FITS format.

The ver_*_sed.fits.gz files contain the published spectral energy distribution data in FITS format.

The ver_*_<N>_lc.png files provide published lightcurve plots in PNG format, where <N> corresponds to the FITS extension in the associated lightcurve data file (i.e., the associated ver_*_lc.fits.gz file).

Please note that associated data products are not available for the following sources (refer to the source_number parameter):

    11, 13, 20, 22, 34, 43, 53, 55, 57, 67, 69, 82, 138, 154.

Parameters

ObsID
An identifier for each set of observations. It is based on the ref_id field.

Source_Number
The numerical identifier for each unique source in the catalog.

Entry_Number
The numerical identifier for each entry of a source in the catalog.

Name
The VERITAS source designation.

SIMBAD_Name
The SIMBAD identifier for source based on cross reference searches.

Component_Flag
The flag that denotes whether the observed object is a diffuse or pulsed (e.g., pulsar) object.

Location_Flag
A flag to indicate the source location: 'gal' for Galactic sources, 'egal' for extragalactic sources and 'uid' for unidentified sources.

RA
The right ascension of the VERITAS source in the selected equinox, based on matching with SIMBAD.

Dec
The declination of the VERITAS source in the selected equinox, based on matching with SIMBAD.

LII
The Galactic longitude of the VERITAS source, based on matching with SIMBAD, in units of degrees.

BII
The Galactic latitude of the VERITAS source, based on matching with SIMBAD, in units of degrees.

Other_Names
A comma-separated list of alternative source designations.

Ref_ID
The bibliographic reference code for the publication from which the provided data were compiled.

File_ID
An identifier for the data products related to this source.

Unique_ID
The unique identifier for each entry in the catalog.

Pub_RA
The right ascension for the source based on fit to the VERITAS data as described in the publication (see ref_id), in the selected equinox.

Pub_RA_Error
The uncertainty in the fitted right ascension, in units of degrees.

Pub_RA_Sys_Err
The systematic uncertainty in the fitted right ascension, in units of degrees.

Pub_Dec
The declination for the source based on fit to the VERITAS data as described in the publication (see ref_id), in the selected equinox.

Pub_Dec_Error
The uncertainty in the fitted declination, in units of degrees.

Pub_Dec_Sys_Err
The systematic uncertainty in the fitted declination, in units of degrees.

Notes
Notes related to the data.

Counts
The background-subtracted counts for the source in the given observation.

Sigma
The statistical significance (i.e., the signal-to-noise ratio) for the source.

Sigma_Post
The statistical significance (i.e., the signal-to-noise ratio) for the source, taking into account the "look-elsewhere" effect.

Exposure
The exposure time for the observation, in units of seconds.

Src_Counts
The total number of counts within the "on" region, i.e., the total source counts.

Bck_Counts
The total number of counts in the "off" region, i.e., the total background counts.

Src_To_Bck_Area
The normalization factor between the "on" and "off" regions, used to scale the source and background counts.

Source_Extent
The source extent, in units of arcsec, of the source assuming either symmetric or asymmetric Gaussian morphology.

Source_Extent_Error
The uncertainty in the source extent, in units of arcsec, of the source assuming either symmetric or asymmetric Gaussian morphology.

Source_Extent_Sys_Err
The systematic uncertainty in the source extent, in units of arcsec, of the source assuming either symmetric or asymmetric Gaussian morphology.

Source_Extent_2
The secondary source extent, in units of arcsec, of the source for asymmetric Gaussian morphology.

Source_Extent_2_Error
The uncertainty in the secondary source extent, in units of arcsec, of the source for asymmetric Gaussian morphology.

Source_Extent_2_Sys_Err
The systematic uncertainty in the secondary source extent, in arcsec, of the source for asymmetric Gaussian morphology.

Position_Angle
The position angle, in units of degrees, for asymmetric Gaussian morphology. The reference frame for the position angle is indicated by the position_angle_flag field.

Position_Angle_Error
The uncertainty in the position angle, in units of degrees, for asymmetric Gaussian morphology.

Position_Angle_Sys_Err
The systematic uncertainty in the position angle, in units of degrees, for asymmetric Gaussian morphology.

Morph_Class
The morphological classification (point source vs. Gaussian) for the source.

Position_Angle_Flag
The flag indicating the frame of reference for the position angle measurement: galactic versus equatorial coordinate system.

Orbital_Date
The reference date for the orbital period calculation (i.e., phase zero definition).

Orbital_Period
The orbital period, in units of days, for the source.

Orbital_Period_Error
The uncertainty in the orbital period, in units of days, for the source.

Orbital_Period_Neg_Err
The lower uncertainty value in the orbital period, in units of days.

Orbital_Period_Pos_Err
The upper uncertainty value in the orbital period, in units of days.

Photflux
The measured photon flux, in units of cm^-2 s^-1.

Photflux_Error
The uncertainty in the measured photon flux, in units of cm^-2 s^-1.

Photflux_Sys_Err
The systematic uncertainty in the measured photon flux, in units of cm^-2 s^-1.

Flux
The energy flux for the source, in units of erg cm^-2 s^-1, calculated by integrating the flux down to the threshold energy defined by the lower_energy field.

Lower_Energy
The lower energy bound assumed in the integrated energy flux calculation, in TeV.

Spec_Lower_Energy
The lower energy bound assumed in the flux calculation based on the spectral fit, in TeV.

Spec_Upper_Energy
The upper energy bound assumed in the flux calculation based on the spectral fit, in TeV.

Spec_Start_Date
The start date and time used for the spectral fit.

Spec_End_Date
The end date and time used for the spectral fit.

Spec_Min_Phase
The start of the orbital phase range for the spectral fit.

Spec_Max_Phase
The end of the orbital phase range for the spectral fit.

Extraction_Radius
The radius, in arcsec, for the extraction aperture used for spectral measurement.

Spec_Model_Type
The flag that specifies the spectral model to fit the VERITAS spectrum. These include:

        pl   = Single power law model fit by the normalization (spec_norm),
               and power law index (spectral_index), in the form:
               dN/dE = spec_norm * (E/spectral_ref_energy)^(-1*spectral_index).
        pl2  = Power law model fit by power law index (spectral_index) of the
               form: dN/dE = spec_norm * (E/spectral_ref_energy)^(-1*spectral_index) *
               (-1*spectral_index + 1)/(- spec_pl2_lower_energy^(-1*spectral_index+1)).
        ecpl = Exponential cutoff power law model fit by normalization
               (spec_norm), power law index (spectral_index), reference
               energy (spectral_ref_energy) and cutoff energy (spec_energy_cut)
               in the form: dN/dE = spec_norm *
               (E/spectral_ref_energy)^(-1*spectral_index) * exp(-E/spec_energy_cut).
        lppl = Log-parabola power law with an index (spec_lppl_index) which
               varies as a log parabola in the form:
  	     dN/dE = spec_norm * (E/spectral_ref_energy)^(spec_lppl_index -
  	     spec_lppl_beta * log(E/spectral_ref_energy)).
        none = none of the models above were used to fit the spectrum.

Spectral_Index
The spectral index parameter for the spectral model fit.

Spectral_Index_Error
The uncertainty in the spectral index parameter for the spectral model fit.

Spectral_Index_Sys_Err
The systematic uncertainty in the spectral index parameter for the spectral model fit.

Spectral_Ref_Energy
The reference energy parameter for the spectral model (pl, pl2, or lppl) fit, in units of TeV.

Chi_Squared
The Chi² statistic for the spectral model fit.

Fit_DoF
The degrees of freedom for the spectral model fit.

Spec_Flux
The energy flux based on the integrated spectral fit, in units of erg cm^-2 s^-1.

Spec_Flux_Error
The uncertainty in the energy flux based on the integrated spectral fit, in units of erg cm^-2 s^-1.

Spec_Flux_Sys_Err
The systematic uncertainty in the energy flux based on the integrated spectral fit, in units of erg cm^-2 s^-1.

Spec_PL2_Lower_Energy
The lower energy bound for the integrated flux measurement for the pl2 model, in TeV.

Spec_Energy_Cut
The cut-off energy parameter for the expl or lppl spectral fit models, in TeV.

Spec_Energy_Cut_Error
The uncertainty in the cut-off energy parameter for the expl or lppl spectral fit models, in TeV.

Spec_LPPL_Index
The spectral index parameter for the lppl spectral fit model.

Spec_LPPL_Index_Error
The uncertainty in the spectral index parameter for the lppl spectral fit model.

Spec_LPPL_Beta
The pre-factor beta parameter for the lppl spectral fit model.

Spec_LPPL_Beta_Error
The uncertainty in the pre-factor beta parameter for the lppl spectral fit model.

Contact Person

Questions regarding the VERIMASTER database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:36:03 EDT