J/ApJS/75/801 MGIV (Fourth MIT-Green Bank) 5GHz Survey (Griffith+ 1991)
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 sources ; Surveys
Keywords: radio sources: general - radio sources: identifications
Abstract:
The MIT-Green Bank IV (MG IV) 5 GHz survey covers 0.504 sr of sky
in the right ascension range 15.5 to 2.5 hours, between +37.00 and
+50.98 degrees declination (B1950). The final MG IV catalog
contains 3427 sources detected with a signal-to-noise ratio
greater than 5. The catalog was produced from two separate north
and south surveys with the National Radio Astronomy Observatory
(NRAO) 91m transit telescope. The north survey was produced from
data collected while scanning the telescope north from +39.0 to
+50.98 degrees declination and the south survey from data
collected from scans from +48.98 to +37.00 degrees declination.
The completeness and reliability of the final source list is
checked by examination of north and south source lists in a twice
observed comparison region, lying between +39.15 and +48.83
degrees declination and excluding the area between ±10 degrees
Galactic latitude. The comparison region covers 0.270 sr of sky
and contains 1094 sources. In this region, the MG IV catalog
contains 423 sources brighter than 90 mJy and is shown to be 99.1
± 1.2% complete at this flux density level. Spectral indices are
computed for sources identified in the NRAO 1400 MHz Survey
(published by Condon and Broderick in 1985). A comparison of the
spectral index distributions between ± 10 and outside of ± 10
degrees Galactic latitude is presented.
Authors' addresses:
MARK GRIFFITH,
BERNARD BURKE, SAM CONNER, and MIKE HEFLIN:
Room 26-335, Massachusetts Institute of Technology,
Cambridge, MA 02139 (Phone 1-617-253-2572)
GLEN LANGSTON
National Radio Astronomy Observatory , Edgemont Road,
Charlottesville, Va 22903 (Phone 1-804-296-0328)
Nomenclature Note:
The source names are derived from the J2000 coordinates;
a 'J' was added in front of this name to comply with
IAU recommendations on designations, and the suffix 'a'
or 'b' was added for 132 sources with identical names.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 78 3427 JMG IV source list
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See also:
VIII/52 : The MIT-Green Bank 5GHz Survey (Bennett+, 1986-91)
VIII/38 : The Parkes-MIT-NRAO 4.85GHz (PMN) Surveys (Griffith+ 1993-1996)
Byte-per-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Name The source names are derived from the
J2000 coordinates
(see "Nomenclature Note" section above)
16- 17 I2 h RAh right ascension J2000
19- 20 I2 min RAm right ascension J2000
22- 25 F4.1 s RAs right ascension J2000
27 A1 --- DE- declination sign
28- 29 I2 deg DEd declination J2000
31- 32 I2 arcmin DEm declination J2000
34- 35 I2 arcsec DEs declination J2000
38- 39 I2 h RA1950h right ascension B1950.0
41- 42 I2 min RA1950m right ascension B1950.0
44- 47 F4.1 s RA1950s right ascension B1950.0
49 A1 --- DE1950- declination sign
50- 51 I2 deg DE1950d declination B1950.0
53- 54 I2 arcmin DE1950m declination B1950.0
56- 57 I2 arcsec DE1950s declination B1950.0
60- 64 I5 mJy S4.83GHz 4.830 GHz Green Bank flux density
67- 68 I2 --- S/N Signal-to-noise ratio of the detection.
The MGIV source list is defined by S/N ≥ 5
71 I1 --- G *Group containing the source
74- 78 F5.2 --- alpha ? The NRAO 1400 MHz-MGIV spectral index,
alpha(1400 MHz, 4830 MHz), where
S ∝ νalpha
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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
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Acknowledgements: Mark Griffith
History:
* 13-Oct-1998: the suffix 'a' or 'b' was added in byte position 14
of table4 to distinguish sources with colliding names.
(done for consecutive identical names)
* 13-Oct-1998: the suffix 'a' 'b' or 'c' was added in byte position 14
(done for all 132 sources with colliding names)
* 22-May-1999: All four parts of MIT-Green Bank merged in Cat. VIII/52
(End) Patricia Bauer, Francois Ochsenbein [CDS] 07-Oct-1998