MITGB6CM - MIT-Green Bank 5-GHz Survey Catalog
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).
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)>
The second MIT-Green Bank 5 GHz survey
Langston G.I., Heflin M.B., Conner S.R., Lehar J., Carrilli C.L.,
<Astrophys. J. Suppl. Ser. 72, 621 (1990)>
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)>
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)>
This online catalog was created by the HEASARC in October 2003
based on CDS catalog VIII/52B (the file mgcat.dat).
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.
The survey number 1, 2, 3, or 4 from which the source was taken.
A flag 's' that indicates sources with signal-to-noise ratios of
less than 5.
The original name of the radio source as listed in the catalog.
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.
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
The Declination of the radio source. This was given in B1950
equatorial coordinates and to a precision of 1 arcseconds in the
The Galactic Longitude of the radio source.
The Galactic Latitude of the radio source.
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.
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.
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).
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".
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.
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.
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.).
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).
Questions regarding the MITGB6CM database table can be addressed to the
HEASARC User Hotline.
If you have any problems, please consult the help
page or mail firstname.lastname@example.org