MITGB6CM - MIT-Green Bank 5-GHz Survey Catalog

Overview

The MIT-Green Bank 5 GHz Survey Catalog was produced from four separate surveys with the National Radio Astronomy Observatory (NRAO) 91m transit telescope, the results from which were presented in papers by Bennett et al., 1986ApJS...61....1B (MG1), Langston et al., 1990ApJS...72..621L (MG2), Griffith et al., 1990ApJS...74..129G (MG3), and Griffith et al. 1991ApJS...75..801G (MG4). The sky coverage of the various surveys is:

    00h    < RAB < 24h,    -00d30'13" < DECB < +19d29'47" for MG1
    04h    < RAJ < 21h,    +17.0d     < DECJ < +39d09'    for MG2
    16h30m < RAB < 05h,    +17d       < DECB < +39d09'    for MG3
    15h30m < RAB < 02h30m, +37.00d    < DECB < +50d58'48" for MG4

where RAB and DECB refer to B1950 coordinates, and RAJ and DECJ refer to J2000 coordinates. The catalog contains 20344 sources detected with a signal-to-noise ratio greater than 5 and 3836 possible detections (MG1) with a signal-to-noise ratio less than 5. Spectral indices are computed for MG1 sources also identified in the Texas 365 MHz survey (Douglas et al. 1980, Univ. Texas Pub. Astr. No. 17), and for MG1-MG4 sources also identified in the NRAO 1400 MHz Survey (Condon and Broderick 1985, AJ, 90, 2540 = 1985AJ.....90.2540C).

Catalog Bibcodes

1986ApJS...61....1B
1990ApJS...72..621L
1990ApJS...74..129G
1991ApJS...75..801G

References

The MIT-Green Bank (MG) 5 GHz survey
    Bennett C.L., Lawrence C.R., Burke B.F., Hewitt J.N., Mahoney J.
    <Astrophys. J. Suppl. Ser. 61, 1 (1986)>
    =1986ApJS...61....1B
The second MIT-Green Bank 5 GHz survey
    Langston G.I., Heflin M.B., Conner S.R., Lehar J., Carrilli C.L.,
    Burke B.F.
    <Astrophys. J. Suppl. Ser. 72, 621 (1990)>
    =1990ApJS...72..621L
The third MIT-Green Bank 5 GHz survey
    Griffith M., Langston G., Heflin M., Conner S., Lehar J., Burke B.
    <Astrophys. J. Suppl. Ser. 74, 129 (1990)>
    =1990ApJS...74..129G
The fourth MIT-Green Bank 5 GHz survey
    Griffith M., Langston G., Heflin M., Conner S., Burke B.
    <Astrophys. J. Suppl. Ser. 75, 801 (1991)>
    =1991ApJS...75..801G

Provenance

This online catalog was created by the HEASARC in October 2003 based on CDS catalog VIII/52B (the file mgcat.dat).

HEASARC Implementation

The HEASARC has created the names that are given in this table in order to have identifications which conform to the naming convention recommended by the Dictionary of Nomenclature of Celestial Objects. Thus, the object with the original name in the CDS table version of MG3 J000335+3747 is named MITG J0003+3747 in this HEASARC table. Since some names would be duplicates for objects lying in very nearly the same directions, in such cases there are prefixes, "a", "b", etc., appended to the names, in order of increasing right ascension. For the sake of completeness, the HEASARC has retained the name field given in the CDS table as the parameter called original_name. Notice that names in the original printed paper versions of this catalog were of the form MG 0003+3747, i.e., they only had 4 characters in the RA part of their name, and were not unique.

The HEASARC has also added a new parameter called survey which identifies in which survey (1, 2, 3 or 4) the source was identified, based on the original name prefix, e.g., survey = 3 for the source used in the example above.

Parameters

Survey
The survey number 1, 2, 3, or 4 from which the source was taken.

Source_Flag
A flag 's' that indicates sources with signal-to-noise ratios of less than 5.

Original_Name
The original name of the radio source as listed in the catalog.

Name
The name of the radio source. Notice that the HEASARC has changed the names given in the original CDS table, e.g., MG3_J000335+3747, in order to conform to the naming convention that is recommended by the Dictionary of Nomenclature of Celestial Objects. Thus, the object above is now named MITG J0003+3747. Since some names would be duplicates for objects lying in similar directions, we have appended prefixes, "a", "b", etc., to the names in such cases, in order of increasing right ascension.

RA
The Right Ascension of the radio source. This was given in B1950 equatorial coordinates and to a precision of 0.1 seconds of time in the original table.

Dec
The Declination of the radio source. This was given in B1950 equatorial coordinates and to a precision of 1 arcseconds in the original table.

LII
The Galactic Longitude of the radio source.

BII
The Galactic Latitude of the radio source.

Flux_6_cm_Limit
This is a flux density limit flag which is left blank if the quoted flux density value is the actual flux density, or is set to '>' if the quoted value is actually a lower limit on the flux density. Notice that MG1 fluxes over 5 Jy (5000 mJy) are listed as "> 5000" due to the receiver saturation.

Flux_6_cm
The flux density in milliJanskies (mJy) measured by the Green Bank 91-m Telescope at either 4.830 or 4.775 GHz, according to the value of the flux_6_cm_flag parameter.

Flux_6_cm_Flag
This flag is left blank if the observing frequency is 4.830 GHz (as in the MG2, MG3, and MG4 Surveys), or is set to "1" if the observing frequency is 4.775 GHz (as in the MG1 Survey).

SNR_6_cm_Limit
This is a signal-to-noise ratio limit flag which is left blank if the quoted SNR value is the actual signal-to-noise, or is set to '>' if it is a lower limit on the actual signal-to-noise. Notice that MG1 SNR values over 100 are listed as ">99.9".

SNR_6_cm
The signal-to-noise ratio of the radio source detection or, if snr_6_cm_limit = ">", the lower limit to the signal-to-noise ratio.

Group_Number
The "group" in which the source was found. Each source is assigned to one of nine groups depending on the source location and on whether the source was found in both the north moving and south moving scans. Sources with b > +10 deg and detected in the south, north, or both surveys are assigned to groups 0, 1, or 2, respectively. Sources lying in regions observed only once or at low Galactic latitude |b| < 10 deg, and detected in the south, north, or both surveys are assigned to groups 3, 4, or 5, respectively. Sources in the region observed twice but with b < -10 deg and detected in the south, north, or both surveys are assigned to groups 6, 7, or 8, respectively.

Spectral_Index
The radio spectral index of the source. The frequencies used to create the spectral index are a function of the value of the spectral_index_flag parameter (q.v.).

Spectral_Index_Flag
This parameter is a flag which indicates what frequencies were used to create the quoted spectral index: it is left blank if the spectral index is derived using NRAO 1400 MHz and Green Bank Telescope 4.830 GHz observations (as in the MG2, MG3 and MG4 Surveys), or is set to "1" if it is derived using Texas 365 MHz and Green Bank Telescope 4.775 GHz observations (as in the MG1 Survey).

Contact Person

Questions regarding the MITGB6CM database table can be addressed to the HEASARC Help Desk.

Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:31:08 EDT