J/AJ/154/23 Southern H II Region Discovery Survey: pilot survey (Brown+, 2017)
The Southern H II Region Discovery Survey (SHRDS): pilot survey.
Brown C., Jordan C., Dickey J.M., Anderson L.D., Armentrout W.P.,
Balser D.S., Bania T.M., Dawson J.R., Mc Clure-Griffiths N.M., Wenger T.V.
<Astron. J., 154, 23 (2017)>
=2017AJ....154...23B 2017AJ....154...23B (SIMBAD/NED BibCode)
ADC_Keywords: Galactic plane ; H II regions ; Infrared sources ; Radio lines ;
Surveys
Keywords: Galaxy: structure - HII regions - radio lines: ISM - surveys
Abstract:
The Southern H II Region Discovery Survey is a survey of the third and
fourth quadrants of the Galactic plane that will detect radio
recombination line (RRL) and continuum emission at cm-wavelengths from
several hundred H II region candidates using the Australia Telescope
Compact Array. The targets for this survey come from the WISE Catalog
of Galactic H II Regions (Anderson et al. 2014, J/ApJS/212/1) and were
identified based on mid-infrared and radio continuum emission. In this
pilot project, two different configurations of the Compact Array Broad
Band receiver and spectrometer system were used for short test
observations. The pilot surveys detected RRL emission from 36 of 53 H II
region candidates, as well as seven known H II regions that were
included for calibration. These 36 recombination line detections
confirm that the candidates are true H II regions and allow us to
estimate their distances.
Description:
The Southern H II Region Discovery Survey (SHRDS) is a multi-year
project using the Australia Telescope Compact Array (ATCA) to
complement the GBT and Arecibo HRDS by extending the survey area into
the southern sky (δ←45°). This area includes the Southern
end of the Galactic Bar, the Near and Far 3 kpc Arms, the Norma/Cygnus
Arm, the Scutum/Crux Arm, the Sagitttarius/Carina Arm, and outside the
solar circle, the Perseus Arm, and the Outer Arm.
All pilot SHRDS observations used the ATCA in the five antenna H75
array configuration, giving a nominal maximum baseline of 75 m and a
beam size of FWHM ∼65" at 7.8 GHz depending on the declination and hour
angles of the observations.
The SHRDS pilot observations were done in two sessions. Epoch I,
observed 2013 June 30, focused on candidates that were expected to
show bright radio recombination line (RRL) detections, which they did.
Epoch II, observed 2014 June 26 and 27, used a list of candidates with
expected flux densities typical of the SHRDS catalog as a whole. The
two epochs also used different longitude ranges in order to generate
samples of H II regions with different Galactic radii.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 47 60 Pilot SHRDS Source Candidates
table2.dat 26 39 Recombination Lines Observed
table3.dat 95 147 Detected RRL Gaussian Parameters
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See also:
J/A+A/171/261 : Radio Recombination Lines of Southern HII Regions
(Caswell+ 1987)
J/A+A/397/213 : Galactic HII regions (Paladini+, 2003)
J/ApJ/653/1226 : Physical properties of galactic HII regions (Quireza+, 2006)
J/ApJS/165/338 : Radio recombination lines in HII regions (Quireza+, 2006)
J/ApJ/690/706 : Distances of Galactic HII regions (Anderson+, 2009)
J/ApJ/738/27 : Galactic HII regions RRL and continuum data (Balser+, 2011)
J/ApJS/194/32 : The HII Region Discovery Survey (HRDS). II. (Anderson+, 2011)
J/ApJ/754/62 : HRDS III. HII region kinematic distances (Anderson+, 2012)
J/ApJS/212/1 : The WISE catalog of Galactic HII regions (Anderson+, 2014)
J/ApJS/221/26 : Radio observations of Galactic WISE HII regions
(Anderson+, 2015)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Region Known H II region or candidate (Cand)
7- 21 A15 --- Name H II region name (GLLL.lll+BB.bbb)
23 I1 --- Epoch [1/2] Epoch of observation (1)
25- 26 I2 --- Nuv [3/13] Number of uv cuts
28- 29 I2 min TObs [10/52] Total observation time
31- 45 A15 --- IRAS IRAS source name (IRAS HHMMm-DDMM)
47 A1 --- Vel [Y-] Known velocity (e.g., stellar or molecular)
probably associated with the region?
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Note (1): Epoch 1 = 30 June 2013; Epoch 2 = 26 and 27 June 2014.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Epoch [I II] Epoch of observation (1)
4- 6 I3 --- Hna [85/117] Hnα transition number
8- 16 F9.3 MHz nuRest [4053.878/10522.04] Rest frequency
18- 22 I5 MHz nuCent [4040/10508] Center frequency (2)
24- 26 F3.1 km/s DVel [0.9/2.3] Velocity resolution ΔV
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Note (1): Epoch defined as follows:
I = Epoch I, ν1=6984, ν2=9900 MHz (30 June 2013);
II = Epoch II, ν1=5000, ν2=7100 MHz (26/27 June 2014).
Note (2): The center frequencies of the 2 GHz bands (ν1 and ν2) are
also listed. See Figure 1.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name H II region name (GLLL.lll+BB.bbb)
17- 19 I3 --- Hna [85/107]? Hnα transition number (1)
20- 21 A2 --- n_Hna [S S2] Note on Hna (2)
23- 29 F7.3 km/s VLSR [-93.5/69.0] Local Standard of Rest Velocity
of line center
31- 34 F4.1 km/s e_VLSR [0.2/20.2] Uncertainty in VLSR
36- 40 F5.1 km/s FWHM [12.2/105.5] Full-width at half-maximum
of line width
42- 45 F4.1 km/s e_FWHM [0.3/20.9] Uncertainty in FWHM
47- 54 F8.2 mJy Sc [106/27000]?=-99.99 Continuum flux density
56- 60 F5.1 mJy rms [1.2/303.0] Spectral root-mean-square noise
62- 67 F6.1 mJy SL [1.9/2479.0] Peak line flux density
69- 72 F4.1 mJy e_SL [1.4/56.0] Uncertainty in SL
74- 81 F8.2 K Te [4500/14000]?=-99.99 Electron temperature (3)
83- 89 F7.2 K e_Te [400/4500]?=-99.99 Uncertainty in Te
91- 95 F5.1 --- S/N [1.5/163.0] Signal-to-noise ratio,
in σ units (4)
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Note (1): For sources bright enough to be detected in individual transitions.
Note (2): Note as follows:
S = Source average. Indicates the detection was made in the average of all
radio recombination line (RRL) transitions;
S2 = The result of the two-Gaussian fit.
Note (3): Estimated from the line-to-continuum ratios.
Note (4): The S/N is computed as (e.g. Lenz & Ayers 1992PASP..104.1104L 1992PASP..104.1104L):
S/N=0.7(SL/rms)*(FWHM/ΔV)0.5.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 28-May-2018