VIII/52B The MIT-Green Bank 5GHz Survey (Bennett+, 1986-91)
The MIT-Green Bank (MG) 5GHz 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 1986ApJS...61....1B
The second MIT-Green Bank 5GHz 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 1990ApJS...72..621L
The third MIT-Green Bank 5GHz survey
Griffith M., Langston G., Heflin M., Conner S., Lehar J., Burke B.
<Astrophys. J. Suppl. Ser. 74, 129 (1990)>
=1990ApJS...74..129G 1990ApJS...74..129G
The fourth MIT-Green Bank 5GHz survey
Griffith M., Langston G., Heflin M., Conner S., Burke B.
<Astrophys. J. Suppl. Ser. 75, 801 (1991)>
=1991ApJS...75..801G 1991ApJS...75..801G
ADC_Keywords: Radio continuum ; Radio sources
Keywords: radio sources: general - radio sources: identifications
Description:
The MIT-Green Bank 5GHz survey catalog was produced from four
separate surveys with the National Radio Astronomy Observatory (NRAO)
91m transit telescope (Bennett et al., 1986ApJS...61....1B 1986ApJS...61....1B (MG1);
Langston et al., 1990ApJS...72..621L 1990ApJS...72..621L (MG2); Griffith et al.,
1990ApJS...74..129G 1990ApJS...74..129G (MG3); Griffith et al. 1991ApJS...75..801G 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; and
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 365MHz survey
(Douglas et al. 1980), and for MG1-MG4 sources also identified in the
NRAO 1400MHz Survey (Condon and Broderick 1985).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
mgcat.dat 70 24180 Merged MG1-4 source list
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See also:
VIII/14 : 87GB Radio Sources 4.85GHz (Gregory, Condon 1991)
VIII/42 : Texas Survey of radio sources at 365MHz (Douglas+ 1996)
A 4.85GHz sky survey. (Condon+ 1994) =1994AJ....107.1829C 1994AJ....107.1829C
90GB 4.85GHz Sky Maps (Condon+ 1995) =1995ADIL...JC...06C
Byte-by-byte Description of file: mgcat.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [MG]
3 I1 --- vno [1,4] Volume number
4 A1 --- f_MG *[s*] Redundancy or low S/N ratio
5- 16 A12 --- MG *Source name
17 A1 --- m_MG *[abcd] Multiplicity indicator on MG
19- 20 I2 h RAh Right ascension J2000 (hours)
21- 22 I2 min RAm Right ascension J2000 (minutes)
23- 26 F4.1 s RAs [0.0/60.0] Right ascension J2000 (seconds)
27 A1 --- DE- Declination sign
28- 29 I2 deg DEd Declination J2000 (degrees)
30- 31 I2 arcmin DEm Declination J2000 (minutes)
32- 33 I2 arcsec DEs [0/60] Declination J2000 (seconds)
35- 36 I2 h RA1950h Right Ascension B1950 (hours)
37- 38 I2 min RA1950m Right Ascension B1950 (minutes)
39- 42 F4.1 s RA1950s Right Ascension B1950 (seconds)
43 A1 --- DE1950- Declination B1950 (sign)
44- 45 I2 deg DE1950d Declination B1950 (degrees)
46- 47 I2 arcmin DE1950m Declination B1950 (minutes)
48- 49 I2 arcsec DE1950s Declination B1950 (seconds)
50 A1 --- l_Flux *? Flux density limit flag
51- 55 I5 mJy Flux Green Bank flux density at 4.830 or 4.775GHz
56 A1 --- n_Flux *[*] '*' when frequency is 4.775GHz (MG1)
57 A1 --- l_S/N *? Signal-to-noise limit flag
58- 61 F4.1 --- S/N Signal-to-noise ratio of the detection, or
lower limit on signal-to-noise.
63 I1 --- G *? Group detection note
65- 69 F5.2 --- Sp+Index ? The spectral index of the source, where
Flux ∝ νalpha
70 A1 --- n_Sp+Index *[*] Note about the computation of Sp+Index
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Note on f_MG:
s = indicates sources with S/N ratio less than 5
* = sources J163211+2014 which appear twice and have incompabile fluxes
a,b,c,d = indicates duplicated sources (added in May 2004,
see the details in the "History" section below).
Note on MG, m_MG:
Names were not in the original publications, and are based on J2000
position (JHHMMSS+DDMM). The multiplicity index is set to a, b, c, d
for sources sharing the same name which are generally observations of
the same source in the overlapping zones, see details in the "History"
section below. In the case of J163211+2014 however the 2 sources look
incompatible, and the flag f_MG is set to '*' in this case.
Note on l_Flux:
blank if 'Flux' is actual flux density
'>' if 'Flux' is lower limit on flux density (MG1 fluxes over 5 Jy
are listed as "> 5000" due to receiver saturation.)
Note on n_Flux:
blank if frequency is 4.830GHz (MG2-4)
'*' if frequency is 4.775GHz (MG1)
Note on l_S/N:
blank if 'S/N' is actual signal-to-noise
'>' if 'S/N' is lower limit on signal-to-noise (MG1 S/N values over
100 are listed as ">99.9".)
Note on G:
G is defined by the north or south survey detecting the source
and the source location in the survey.
Sources with b > +10 deg and detected in the south, north, or both
surveys are assigned to groups 0, 1, 2.
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.
Sources in the region observed twice but with b < -10 deg and
detected in south, north, or both surveys, are assigned to
groups 6, 7, or 8.
Note on n_Sp+Index:
blank if spectral index derived using NRAO 1400MHz and 4.830GHz
observations (MG2-4)
"*" if derived using Texas 365MHz and 4.775GHz observations (MG1)
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History:
* April 1999: the first merged version of the catalog was prepared by
H.Andernach; following a suggestion by Glen Langston on 25-Mar-1998,
in reply to an inquiry by the IAU TG on Designations, this version
contained names (incorrectly) expanded to MGn_Jhhmmss+ddmm. The
documentation of this version was written by Tom Sodroski [SSDOO/ADC].
* August 2003: the error in the name expansion was corrected after
(painfully) recovering the original catalog files with J2000
coordinates (from NED, thanks to H.G. Corwin Jr.). 23994 unique names
(in the format Jhhmmss+ddmm) resulted from the merging of the 24180
sources. The duplications are all due to overlaps between various
pairs of the 4 parts of the survey, except for the case of MG3
J163211+2014 which appears duplicate in the same paper (III) with
slightly different coordinates (11" apart) and slightly different
flux. They are differentiated by an appended letter 'a' and 'b' in
byte 17 of the catalog.
* 14-May-2004: the values a, b, c, d were added in m_MG to all sources
having duplicate names, and the f_MG flag was set to '*' for the
J163211+2014 case.
References:
Condon, J. J., and Broderick, J. J. 1985, AJ, 90, 2540 =1985AJ.....90.2540C 1985AJ.....90.2540C
Douglas, J. N., Bash, F. N., Torrence, G. W., and Wolfe, C. 1980, The Texas
Survey: Preliminary +18 deg Strip (Univ. Texas Pub. Astr. No. 17).
=1980PAUTx..17....1D 1980PAUTx..17....1D (see also the Texas Survey, Cat. VIII/42)
(End) H.A. Andernach [Guanajuato Univ.], Tom Sodroski [SSDOO/ADC] 28-Aug-2003