J/AJ/128/1646 The Galactic Center region at 330MHz (Nord+, 2004)
High-resolution, wide-field imaging of the Galactic Center region at 330 MHz.
Nord M.E., Lazio T.J.W., Kassim N.E., Hyman S.D., Larosa T.N., Brogan C.L.,
Duric N.
<Astron. J., 128, 1646-1670 (2004)>
=2004AJ....128.1646N 2004AJ....128.1646N
ADC_Keywords: Radio continuum ; Interferometry ; Pulsars
Keywords: Galaxy: center - radio continuum: general -
techniques: interferometric
Abstract:
We present a wide-field, subarcminute-resolution VLA image of the
Galactic center region at 330MHz. With a resolution of ∼7"x12" and an
rms noise of 1.6mJy/beam, this image represents a significant increase
in resolution and sensitivity over the previously published VLA image
at this frequency. The improved sensitivity has more than tripled the
census of small-diameter sources in the region, has resulted in the
detection of two new nonthermal filaments (NTFs), 18 NTF candidates,
and 30 pulsar candidates, reveals previously known extended sources in
greater detail, and has resulted in the first detection of Sagittarius
A* in this frequency range.
Description:
Two sets of observations were obtained. The first was observed at
330MHz in the A configuration of the VLA in 1996 October. The second
set of observations were obtained in the A and B configurations of the
VLA and were obtained between 1998 March and 1999 May.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 84 241 Galactic Center P-band Survey of Small-Diameter
Sources
table3.dat 101 144 Radio cross-identifications
table4.dat 45 4 Detected pulsars
table5.dat 43 10 Pulsar nondetections
table6.dat 36 30 Pulsar candidates
--------------------------------------------------------------------------------
See also:
J/ApJS/74/181 : Small-diameter radiosources catalogue (Zoonematkermani+, 1990)
J/ApJS/91/347 : A 5-GHz VLA Survey of the Galactic Plane (Becker+ 1994)
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
J/A+A/368/835 : Soft X-ray sources in the Galactic Center region
(Sidoli+, 2001)
J/A+A/433/117 : L- + M-band imaging of the Galactic Center (Viehmann+, 2005)
J/A+AS/52/63 : H I Survey of the Galactic Center Region (Burton+ 1983)
J/ApJ/589/225 : Chandra X-ray sources toward Galactic Center
(Feigelson+, 2003)
J/ApJS/118/201 : Galactic Center 6 and 20cm survey (Lazio+, 1998)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- GCPS GCPS Source number
5- 17 A13 --- Name Source name (G1)
19 A1 --- f_Name [b] Flag on Name (1)
21- 22 I2 h RAh Hour of right ascension (J2000)
24- 25 I2 min RAm Minute of right ascension (J2000)
27- 31 F5.2 s RAs Second of right ascension (J2000)
33 A1 --- DE- Sign of the Declination (J2000)
34- 35 I2 deg DEd Degree of declination (J2000)
37- 38 I2 arcmin DEm Arcminute of declination (J2000)
40- 43 F4.1 arcsec DEs Arcsecond of declination (J2000)
45- 49 F5.1 mJy Imax Maximum intensity (2)
51- 54 F4.1 mJy e_Imax Local rms of the image (2)
56- 61 F6.1 mJy S330MHz Flux density at 330MHz
63- 66 F4.1 arcsec theta Average deconvolved size
68- 72 F5.1 arcmin Offset Source offset from the phase center (3)
74- 83 A10 --- SIM Additional SIMBAD information within 1' (4)
--------------------------------------------------------------------------------
Note (1): Flag on Name:
b = Transient source (see Hyman et al. 2002AJ....123.1497H 2002AJ....123.1497H).
Note (2): In units of mJy/beam, where the FWHM of the beam is 12.58" by 6.81".
Note (3): Phase center R.A.=17:45:40.045, decl.=-29:00:27.900 (J2000).
Note (4): Stellar matches were neglected, and radio source matches are
in Table 3. Types of sources are described as follows:
PSR = Pulsar;
IRAS = IRAS infrared source;
YSO = Young stellar object;
X = X-ray object;
PN = Planetary nebula;
PN? = Possible planetary nebula;
IR = Isogal infrared source;
XRB = X-ray binary;
H II = H II region;
OPC = Open cluster;
MC = Molecular cloud;
SY1 = Seyfert 1 galaxy.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Name Name (G1)
16- 21 F6.1 mJy S330MHz Flux density at 330MHz
25- 29 F5.2 arcsec Diam Angular diameter
34- 46 A13 --- GPSR ? Name in the GPSR catalog (1)
50- 53 F4.1 --- SI1 ? Spectral index 1.4-0.33GHz from GPSR (1)
58- 70 A13 --- 2LC ? Name in the 2LC catalog (2)
74- 77 F4.1 --- SI2 ? Spectral index 1.4-0.33GHz from 2LC (2)
82- 94 A13 --- GPSR5 ? Name in the GPSR5 catalog (3)
98-101 F4.1 --- SI3 ? Spectral index 5-0.33GHz from GPSR5 (3)
--------------------------------------------------------------------------------
Note (1): Zoonematkermani et al. 1990, Cat. J/ApJS/74/181;
Helfand et al. 1992ApJS...80..211H 1992ApJS...80..211H.
Note (2): Lazio & Cordes 2004, in prep.
Note (3): Becker et al. 1994, Cat. J/ApJS/91/347.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Name Source Name (G1)
17- 26 A10 --- PSR Pulsar name from Taylor et al (1993, see
Cat. VII/189) and the ATNF Pulsar Catalogue
(Cat. J/AJ/129/1993).
29- 31 F3.1 arcsec Diam Angular diameter
34- 39 F6.1 mJy S330MHz Flux density at 330MHz
42- 45 F4.1 --- Sp+Index Spectral index 1.4-0.33GHz
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- PSR Pulsar Name
17- 19 I3 arcmin Dist Distance from phase center
25- 28 F4.2 mJy S1.4GHz Flux density at 1.4GHz
32- 35 F4.1 mJy S0.33GHz 3σ flux density at 0.33GHz (1)
40- 43 F4.1 mJy Sp+Index Spectral index 1.4-0.33GHz in mJy/beam (2)
--------------------------------------------------------------------------------
Note (1): The 330MHz flux density required for a 3σ detection at the
location of the pulsar.
Note (2): Lower limit based on 3σ nondetection.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Name Name (G1)
17- 20 F4.2 arcsec Diam Angular diameter
23- 28 F6.1 mJy S330MHz Flux density at 330MHz
32- 35 F4.1 --- Sp+Index Spectral index 1.4-0.33GHz
36 A1 --- f_Sp+Index Flag on Sp+Index (1)
--------------------------------------------------------------------------------
Note (1): Flag on Sp+Index, defined as follows:
a = Spectral index implied by nondetection in the GPSR (Zoonematkermani et
al. 1990, Cat. J/ApJS/74/181; Helfand et al. 1992ApJS...80..211H 1992ApJS...80..211H) and
should be considered an upper limit.
b = Spectral index measured against the NVSS (Condon et al. 1998,
Cat. VIII/65), not the GPSR. The NVSS has a resolution of 45',
so spectral index values should be considered an upper limit.
--------------------------------------------------------------------------------
Global Notes:
Note (G1): Name is using the source Galactic coordinates.
In Simbad, it is written: GCPS LLL.lll+B.bbb.
--------------------------------------------------------------------------------
History:
* 14-Apr-2005: From electronic version of the journal
* 01-Jun-2005: Names standardized, e.g. 2.186+0.043 transformed
into 002.186+0.043 to comply to IAU standards.
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 14-Apr-2005