J/ApJS/183/214 Arecibo Legacy Fast Alfa Survey (ALFALFA) VIII. (Martin+, 2009)
The Arecibo Legacy Fast Alfa Survey.
VIII. H I source catalog of the anti-Virgo region at δ = +25°.
Martin A.M., Giovanelli R., Haynes M.P., Saintonge A., Hoffman G.L.,
Kent B.R., Stierwalt S.
<Astrophys. J. Suppl. Ser., 183, 214-224 (2009)>
=2009ApJS..183..214M 2009ApJS..183..214M
ADC_Keywords: Surveys ; H I data ; Galaxies, radio ; Redshifts
Keywords: catalogs - galaxies: distances and redshifts - galaxies: photometry -
galaxies: spiral - radio lines: galaxies - surveys
Abstract:
We present a fourth catalog of HI sources from the Arecibo Legacy Fast
ALFA (ALFALFA) Survey. We report 541 detections over 136deg2,
within the region of the sky having 22h<RA<03h and 24<DE<26°.
This complements a previous catalog in the region 26<DE<28°. We
present here the detections falling into three classes: (1)
extragalactic sources with signal-to-noise ratio (S/N)>6.5, where the
reliability of the catalog is better than 95%; (2) extragalactic
sources 5.0<S/N<6.5 and a previously measured optical redshift that
corroborates our detection; or (3) High Velocity Clouds (HVCs), or
subcomponents of such clouds, in the periphery of the Milky Way. Of
the 541 objects presented here, 90 are associated with HVCs, while the
remaining 451 are identified as extragalactic objects. Optical
counterparts have been matched with all but one of the extragalactic
objects.
Description:
ALFALFA observations are conducted at the Arecibo telescope, using the
7 pixel ALFA receiver installed in 2004.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 102 541 HI candidate detections
notes.dat 80 229 Comments from section 3
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See also:
VIII/73 : HI Parkes All Sky Survey Catalogue (HIPASS) (Meyer+, 2004)
VIII/77 : HI spectral properties of galaxies (Springob+, 2005)
J/AJ/113/905 : HI observations of galaxies (Pantoja+ 1997)
J/MNRAS/357/819 : Colours and HI line observations in Virgo (Sabatini+, 2005)
J/AJ/130/2613 : The Arecibo Legacy Fast ALFA survey. II (Giovanelli+, 2005)
J/AJ/133/2569 : Arecibo legacy fast ALFA survey III. (Giovanelli+, 2007)
J/AJ/135/588 : Arecibo legacy fast ALFA survey V. (Saintonge+, 2008)
http://arecibo.tc.cornell.edu/hiarchive : ALFALFA data access
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [4-]
3- 5 I3 --- ALFALFA4 [1/541] Catalog entry number,
ALFALFA 4-NNN in Simbad
7- 12 I6 --- AGC Arecibo General Catalog number
14- 15 I2 h RAh HI Hour of Right Ascension (J2000) (1)
17- 18 I2 min RAm HI Minute of Right Ascension (J2000)
20- 23 F4.1 s RAs HI Second of Right Ascension (J2000)
25 A1 --- DE- Sign of the HI Declination (J2000) (1)
26- 27 I2 deg DEd HI Degree of Declination (J2000)
29- 30 I2 arcmin DEm HI Arcminute of Declination (J2000)
32- 33 I2 arcsec DEs HI Arcsecond of Declination (J2000)
35- 36 I2 h RAOh ? Optical Hour of Right Ascension (J2000) (2)
38- 39 I2 min RAOm ? Optical Minute of Right Ascension (J2000)
41- 44 F4.1 s RAOs ? Optical Second of Right Ascension (J2000)
46 A1 --- DEO- Sign of the Opical Declination (J2000) (2)
47- 48 I2 deg DEOd ? Optical Degree of Declination (J2000)
50- 51 I2 arcmin DEOm ? Optical Arcminute of Declination (J2000)
53- 54 I2 arcsec DEOs ? Optical Arcsecond of Declination (J2000)
56- 60 I5 km/s cz HI heliocentric velocity (3)
62- 64 I3 km/s W50 Source line profile velocity width (4)
66- 68 I3 km/s e_W50 Uncertainty in W50 (5)
70- 75 F6.2 Jy.km/s Fc Source integrated flux density (6)
77- 81 F5.1 --- S/N Signal-to-noise (7)
83- 87 F5.2 mJy rms Integrated spectral profile noise figure (8)
89- 93 F5.1 Mpc Dist ? Adopted distance (9)
95- 99 F5.2 [solMass] logM ? Log of HI mass (10)
101 I1 --- Qual Object quality code (11)
102 A1 --- n_ALFALFA4 [*] * indicates additional comments provided
in notes.dat file
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Note (1): HI center after correction for systematic telescope pointing
errors, which are on the order of 20" and depend on declination. The
accuracy of the HI positions, compared to the positions of the optical
counterparts, depends on source strength. On average, the positional
accuracy, estimated as the difference between the HI position and the
optical counterpart, is about 18".
Note (2): Optical counterpart center matched with the source. No optical
counterpart is listed for High Velocity Clouds. The position has been
checked for each listed ob ject and assessed using tools provided
through the SkyView website, in addition to NED and the AGC. The
quality of centroids is estimated to be 2" or better.
Note (3): Measured as the midpoint between the channels at which the flux
density drops to 50% of each of the two peaks (or of one, if only one
is present) at each side of the spectral feature.
Note (4): Measured at the 50% level of each of the two peaks. This value
is corrected for instrumental broadening. No corrections due to
turbulent motions, disk inclination or cosmological effects are
applied.
Note (5): This error is the sum in quadrature of two components: the first
is a statistical error; the second is a systematic error associated
with the subjective guess with which the observer estimates the
spectral boundaries of the feature, flagged during the interactive
assessment of candidate detections. In the majority of cases, the
systematic error is significantly smaller than the statistical error;
thus the former is ignored.
Note (6): This is measured on the integrated spectrum, obtained by
spatially integrating the source image over a solid angle of at least
7'x7' and dividing by the sum of the survey beam values over the same
set of image pixels (see Shostak & Allen, 1980A&A....81..167S 1980A&A....81..167S).
Integrated fluxes for very extended sources with large spatial
asymmetries can be misestimated by our algorithm, which is not
optimized for that category of sources.
Note (7): Estimated as S/N=((1000Fc)/W50)x(Wsmo1/2/rms). The ratio
1000Fc/W50 is the mean flux across the feature, Wsmo is either
W50/(2x10) for W50<400km/s or 400/(2x10)=20 for W50≥400km/s [wsmo
is a smoothing width expressed as the number of spectral resolution
bins of 10km/s bridging half of the signal width].
Note (8): The noise figure as tabulated is the r.m.s. as measured over the
signal- and RFI-free portions of the spectrum, after Hanning smoothing
to a spectral resolution of 10km/s.
Note (9): For objects with cz☉>6000km/s, the distance is simply
estimated as czcmb/H0; czcmb is the recessional velocity
measured in the Cosmic Microwave Background reference frame and H0
is the Hubble constant, for which we use a value of 70km/s/Mpc. For
objects of lower czcmb, we use the local universe peculiar velocity
model of Masters, as described in Paper II (Giovanelli et al., 2005,
Cat. J/AJ/130/2613), which is based on data from the SFI++ catalog of
galaxies (Springob et al., 2007, Cat. J/ApJS/172/599). In cases where
a galaxy has a known primary distance, that distance will be adopted;
when the galaxy is a known member of a group, that group's recessional
velocity czcmb is used to determine the distance.
Note (10): Where MHI=2.356x105Dist2Fc.
Note (11): Quality is numbered with values as follows:
1 = S/N and general qualities make it a reliable detection.
2 = low S/N (<6.5), which would ordinarily not be considered a reliable
detection by the criteria set for code 1. However, HI candidate
source is matched with an optical counterpart with known optical
redshifts which match those measured in the HI line.
9 = assumed to be a HVC.
See text for additional details.
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [4-]
3- 5 I3 --- ALFALFA4 Catalog entry number
7- 80 A74 --- Note Section 3 comment
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History:
From electronic version of the journal
References:
Giovanelli et al., Paper I 2005AJ....130.2598G 2005AJ....130.2598G
Giovanelli et al., Paper II 2005AJ....130.2613G 2005AJ....130.2613G, Cat. J/AJ/130/2613
Giovanelli et al., Paper III 2007AJ....133.2569G 2007AJ....133.2569G, Cat. J/AJ/133/2569
Saintonge et al., Paper IV 2007AJ....133.2087S 2007AJ....133.2087S
Saintonge et al., Paper V 2008AJ....135..588S 2008AJ....135..588S, Cat. J/AJ/135/588
Kent et al., Paper VI 2008AJ....136..713K 2008AJ....136..713K, Cat. J/AJ/136/713
Kent et al., Paper VII 2009ApJ...691.1595K 2009ApJ...691.1595K
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 18-Jan-2010