J/ApJS/282/18 Green Bank Ammonia Survey (GAS) DR2 (Pineda+, 2026)
The Green Bank Ammonia Survey: Data Release 2.
Pineda J.E., Friesen R.K., Rosolowsky E., Chacon-Tanarro A., Chen M.C.-Y.,
Di Francesco J., Kirk H., Punanova A., Seo Y., Shirley Y., Ginsburg A.,
Offner S.S.R., Pandhi A., Singh A., Quan F., Arce H.G., Caselli P.,
Choudhury S., Goodman A.A., Heitsch F., Martin P.G., Matzner C.D.,
Myers P.C., Redaelli E., Scibelli S., co-PIs, The GAS collaboration
<Astrophys. J. Suppl. Ser., 282, 18 (2026)>
=2026ApJS..282...18P 2026ApJS..282...18P
ADC_Keywords: Molecular clouds; Space velocities; Velocity dispersion;
Interstellar medium; Molecular data; Radio lines
Keywords: Star formation ; Interstellar molecules ; Astrochemistry
Abstract:
We present an overview of the final data release (DR2) from the Green
Bank Ammonia Survey (GAS). GAS is a large program at the Green Bank
Telescope to map all Gould Belt star-forming regions with AV≳7mag
visible from the Northern Hemisphere in emission from NH3 and other
key molecular tracers. This final release includes the data for all
the regions observed: Heiles Cloud 2 and B18 in Taurus; Barnard 1,
Barnard 1-E, IC 348, NGC 1333, L1448, L1451, and Per7/34 in Perseus;
L1688 and L1689 in Ophiuchus; Orion A (North and South) and Orion B in
Orion; Cepheus; B59 in Pipe; Corona Australis East and West; IC 5146;
and Serpens Aquila and MWC297 in Serpens. Similar to what was
presented in GAS DR1, we find that the NH3 emission and dust continuum
emission from Herschel correspond closely. We find that the NH3
emission is generally extended beyond the typical 0.1pc length scales
of dense cores, and we find that the transition between coherent core
and turbulent cloud is a common result. This shows that the regions of
coherence are common throughout different star-forming regions, with a
substantial fraction of the high column density regions displaying
subsonic nonthermal velocity dispersions. We produce maps of the gas
kinematics, temperature, and NH3 column densities through forward
modeling of the hyperfine structure of the NH3 (1,1) and (2,2) lines.
We show that the NH3 velocity dispersion, σv, and gas kinetic
temperature, TK, vary systematically between the regions included in
this release, with an increase in both the mean value and spread of
σv and TK with increasing star formation activity.
Description:
The Green Bank Ammonia Survey (GAS) survey's goals were to map all
regions with visual extinctions AV≳7mag toward the Northern
Hemisphere-visible molecular clouds in the Gould Belt. This selection
comprises many of the star-forming clouds within ∼500pc of the Sun.
Overall, GAS mapped ∼4deg2 on sky over nine clouds with distances
ranging from ∼120 to ∼400pc, with one cloud (IC 5146) at a distance of
∼800pc.
Observations for the GAS survey were performed from 2015 January
through 2016 March at the Robert C. Byrd Green Bank Telescope (GBT)
using the 7 pixel K-band Focal Plane Array (KFPA) and the Versatile
GBT Astronomical Spectrometer (VEGAS). Observational details were
first presented in GAS DR1 (Friesen+ 2017ApJ...843...63F 2017ApJ...843...63F), which
focused on the NH3 (1,1) and (2,2) emission from four regions.
The GAS uses VEGAS configuration Mode 20, allowing eight separate
spectral windows per KFPA beam --each with a bandwidth of 23.44MHz
and 4096 spectral channels-- for a spectral resolution of 5.7kHz, or
∼0.07km/s at 23.7GHz.
The data presented in this paper are publicly available via
doi:10.11570/24.0091.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 41 26 Observed regions, distances, and masses
table8.dat 246 399 NH3 core properties for selected regions
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See also:
VIII/64 : Westerhout's Catalogue of 82 Discrete Sources (Westerhout 1958)
J/ApJS/125/161 : A database of dense cores mapped in ammonia (Jijina+, 1999)
J/ApJ/526/788 : Survey of infall motions toward starless cores (Lee+, 1999)
J/ApJS/153/523 : Starless cores in CS(3-2) and DCO+(2-1) lines (Lee+, 2004)
J/A+A/487/993 : MAMBO Mapping of c2d Clouds and Cores (Kauffmann+, 2008)
J/ApJS/175/509 : Ammonia spectral atlas in Perseus (Rosolowsky+, 2008)
J/MNRAS/426/1972 : H2O Southern Gal. Plane Survey, HOPS. II (Purcell+, 2012)
J/A+A/544/A146 : ATLASGAL cold high-mass clumps with NH3 (Wienen+, 2012)
J/ApJ/779/113 : IR photometry of YSOs in the W40 region (Mallick+, 2013)
J/ApJS/220/11 : SEDs of Spitzer YSOs in the Gould Belt (Dunham+, 2015)
J/ApJ/830/127 : CLASSy: CARMA obs. in L1451 region of Perseus (Storm+, 2016)
J/ApJ/846/144 : Virial analysis of the dense cores in Orion A (Kirk+, 2017)
J/ApJ/867/151 : YSOs in the Gould Belt regions with Gaia-DR2 (Dzib+, 2018)
J/ApJ/859/33 : GOBELINS. IV. VLBA obs. of Taurus (Galli+, 2018)
J/A+A/619/A106 : 3D shape of Orion A from Gaia DR2 (Grossschedl+, 2018)
J/A+A/610/A77 : Orion Integral Filament ALMA+IRAM30m N2H+ (Hacar+, 2018)
J/AJ/156/84 : APOGEE-2 survey of Orion Complex. II. (Kounkel+, 2018)
J/ApJ/865/73 : GOBELINS. V. Kinematics of Perseus (Ortiz-Leon+, 2018)
J/A+A/658/A104 : HL Tau SO2 14(0-14)-13(1,13) datacube (Garufi+, 2022)
J/A+A/667/A12 : PRODIGE I. Per-emb-50 datacubes (Valdivia-Mena+, 2022)
J/A+A/677/A92 : Flow of gas in Barnard 5 (Valdivia-Mena+, 2023)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Cloud Cloud name
11- 23 A13 --- Region Molecular cloud named substructure
(as in Table 8)
25- 29 F5.1 pc Dist [126.6/813] Distance
31- 34 F4.2 deg2 Area [0.01/0.39] Area
36- 39 I4 Msun Mass [8/3141] Total mass (1)
41 I1 --- Ref [1/8]? Reference (2)
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Note (1): The mass listed is the total mass within the extent of the area
mapped by GAS, calculated from dust continuum opacity and temperatures
maps derived from spectral energy distribution fitting of
submillimeter continuum data at similar resolution to the NH3
observations (Singh & Martin 2022ApJ...941..135S 2022ApJ...941..135S).
Note (2): Reference as follows:
1 = Galli et al. (2018, J/ApJ/859/33)
2 = Zucker et al. 2018ApJ...869...83Z 2018ApJ...869...83Z
3 = Ortiz-Leon et al. (2018, J/ApJ/865/73)
4 = Ortiz-Leon et al. 2018ApJ...869L..33O 2018ApJ...869L..33O
5 = Grosschedl et al. (2018, J/A+A/619/A106)
6 = Kounkel et al. (2018, J/AJ/156/84)
7 = Dzib et al. (2018, J/ApJ/867/151)
8 = Yan et al. 2019A&A...624A...6Y 2019A&A...624A...6Y
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Region Molecular cloud named substructure
15- 17 I3 --- GASID [0/253] Dendrogram index within Region (1)
19- 20 I2 h RAh [3/22] Hour of right ascension (J2000)
22- 23 I2 min RAm Minute of right ascension (J2000)
25- 28 F4.1 s RAs Second of right ascension (J2000)
30 A1 --- DE- Sign of declination (J2000)
31- 32 I2 deg DEd Degree of declination (J2000)
34- 35 I2 arcmin DEm Arcminute of declination (J2000)
37- 40 F4.1 arcsec DEs Arcsecond of declination (J2000)
42- 53 F12.9 km/s vLSR [-8.2/12.4]? Mean local standard of rest
velocity across core
55- 65 F11.9 km/s e_vLSR [0.009/3.2]? One-sigma uncertainty in vLSR
67- 77 F11.9 km/s Sigma [0.1/3.2]? Mean velocity dispersion across
core
79- 89 F11.9 km/s e_Sigma [0.005/3]? One-sigma uncertainty in Sigma
91- 102 F12.9 K Tex [2.86/10.64]? Mean excitation temperature
derived from NH3 (1,1) and (2,2) fits across
core
104- 114 F11.9 K e_Tex [0/2.31]? One-sigma uncertainty in Tex
116- 127 F12.9 K Tkin [7.85/46.2]? Mean kinetic temperature derived
from NH3 (1,1) and (2,2) fits across core
129- 140 F12.9 K e_Tkin [0/17.32]? One-sigma uncertainty in Tkin
142- 152 F11.8 cm-2 logNNH3 [13.57/14.97]? Mean of logarithm of NH3
column density across core
154- 164 F11.9 cm-2 e_logNNH3 [0/0.42]? One-sigma uncertainty in logNNH3
166- 176 F11.9 km/s sigth [0.16/0.41]? Thermal line width of H2 given
mean kinetic temperature of core
178- 188 F11.9 km/s signth [0.07/3.2]? Mean non-thermal component of
line width given mean kinetic temperature of
core
190- 210 A21 --- contID ID of cross-matched continuum counterpart of
core (1)
212- 216 F5.3 pc contr [0.006/0.16] Radius of core as derived using
continuum data
218- 224 F7.3 Msun contM [0/166] Mass of core as derived using
continuum data
226- 233 F8.3 --- alpha [0.16/9760]? Virial parameter of core
235- 246 A12 --- CType Core classification as starless, prestellar,
or protostellar
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Note (1): From the Green Bank Ammonia Survey data (Pandhi+ 2023MNRAS.525..364P 2023MNRAS.525..364P).
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History:
From electronic version of the journal
License: CC-BY-4.0
References:
Friesen et al. DR1 2017ApJ...843...63F 2017ApJ...843...63F
Kirk et al. 2017ApJ...846..144K 2017ApJ...846..144K Cat. J/ApJ/846/144
Keown et al. 2017ApJ...850....3K 2017ApJ...850....3K
Redaelli et al. 2017ApJ...850..202R 2017ApJ...850..202R
Kerr et al. 2019ApJ...874..147K 2019ApJ...874..147K
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Jul-2026