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J/ApJS/166/526      Compact extragalactic radio sources              (Xu+, 2006)

Search for compact extragalactic radio sources near massive star-forming regions. Xu Y., Reid M.J., Menten K.M., Zheng X.W. <Astrophys. J. Suppl. Ser., 166, 526-533 (2006)> =2006ApJS..166..526X
ADC_Keywords: Galaxies, radio Keywords: astrometry - radio continuum: galaxies Abstract: We have used the Very Large Array to search for compact milliarcsecond-size radio sources near methanol masers in high-mass star-forming regions. Such sources are required for very long baseline Interferometry phase-referencing observations. We conducted pointed observations of 234 compact sources found in the NVSS survey and find 92 sources with unresolved components and synchrotron spectral indexes. These sources are likely the cores of AGNs and, thus, are good candidates for astrometric calibrators. Description: On 2004 April 2 we made snapshot observations of our 234 sources using the NRAO5 VLA in its C configuration at C band (4.885GHz) and U band (14.939GHz). In order to obtain better positional accuracy and check on compactness, we reobserved 53 sources that had flux densities higher than 5mJy in both the C and U bands and were unresolved in C band. These observations were done as low-priority observations in small gaps in the VLA schedule in the A or B array at U band on 2004 September 26, 27, 28, October 29, and 2005 May 1, 10, and 26, respectively. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 50 38 12.2GHz Methanol maser sources considered table3.dat 33 126 Sources resolved in C- or U-band observations table4.dat 97 129 Parameters of possible calibrators
See also: VIII/40 : GB6 catalog of radio sources (Gregory+ 1996) VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998) J/MNRAS/332/422 : Galaxies morphology and IR photometry. VIII (Pierini+, 2002) J/AJ/129/1163 : Third VLBA calibrator survey: VCS3 (Petrov+, 2005) J/A+A/413/233 : 12.2 GHz methanol survey (Blaszkiewicz+, 2004) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 12 A12 --- Source 12.2GHz Methanol maser source name 13 A1 --- n_Source [a] Indicates no detected compact extragalactic radio sources within 1° 15- 16 I2 h RAh ? Hour of Right Ascension (J2000.0) 18- 19 I2 min RAm ? Minute of Right Ascension (J2000.0) 21- 24 F4.1 s RAs ? Second of Right Ascension (J2000.0) 26 A1 --- DE- Sign of the Declination (J2000.0) 27- 28 I2 deg DEd ? Degree of Declination (J2000.0) 30- 31 I2 arcmin DEm ? Arcminute of Declination (J2000.0) 33- 34 I2 arcsec DEs ? Arcsecond of Declination (J2000.0) 36- 50 A15 --- Region Name of the region containing the maser source
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 13 A13 --- Source Source name 14 A1 --- f_Source [ab] Known Source (1) 16- 17 I2 h RAh Hour of Right Ascension (J2000.0) (2) 19- 20 I2 min RAm Minute of Right Ascension (J2000.0) (2) 22- 23 I2 s RAs Second of Roght Ascension (J2000.0) (2) 25 A1 --- DE- Sign of the Declination (J2000.0) (2) 26- 27 I2 deg DEd Degree of Declination (J2000.0) (2) 29- 30 I2 arcmin DEm Arcminute of Declination (J2000.0) (2) 32- 33 I2 arcsec DEs Arcsecond of Declination (J2000.0) (2)
Note (1): Flag on Name, defined as follows: a = Known HII region according to SIMBAD astronomical database and/or source with rising spectrum. b = Planetary nebula according to SIMBAD astronomical database. Note (2): Position derived from name.
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 12 A12 --- Source Maser source name 14- 31 A18 --- Name Calibrator name 33 A1 --- n_Name Flag on Name (1) 35- 36 I2 h RAh Calibrator Hour of Right Ascension (J2000) 38- 39 I2 min RAm Calibrator Minute of Right Ascension (J2000) 41- 47 F7.4 s RAs Calibrator Second of Right Ascension (J2000) 49 A1 --- DE- Sign of the Calibrator Declination (J2000) 50- 51 I2 deg DEd Calibrator Degree of Declination (J2000) 53- 54 I2 arcmin DEm Calibrator Arcminute of Declination (J2000) 56- 61 F6.3 arcsec DEs Calibrator Arcsecond of Declination (J2000) 63- 68 F6.1 mJy S1.4GHz ? NVSS L band 1.4GHz integrated flux density (2) 70- 74 F5.1 mJy S5GHz ? C band 5GHz peak flux density (2) 76- 80 F5.1 mJy S15GHz ? U band 15GHz peak flux density (2) 82- 86 F5.2 --- alpha ? Spectral index (3) 88- 90 F3.1 arcsec theta Upper limit on maser size (4) 92 A1 --- n_theta [abc] U-band data VLA configuration (5) 94- 97 F4.2 deg Sep Separation between maser and calibrator
Note (1): Flag on Name, defined as follows: d = Source listed in Gregory & Condon (1991, Cat. VIII/40). e = Source listed in VLBA calibrator source (Petrov et al. 2005, Cat. J/AJ/129/1163). Note (2): NULL values indicate sources have no data due to failure of the telescope. Note (3): Between C- and U- bands (S(ν)∝ν). Note (4): FWHM of the maximum major axes of the sources as determined from the Gaussian fits using AIPS task JMFIT. The data come from C-band observed with C-configuration, except those marked by signs. Note (5): Flag on theta, defined as follows: a = U-band data observed with C configuration. b = U-band data observed with A configuration. c = U-band data observed with B configuration.
History: From electronic version of the journal
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 03-Apr-2007
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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