J/AJ/138/338 Arecibo Legacy Fast ALFA Survey. IX. (Stierwalt+, 2009)
The Arecibo Legacy Fast ALFA Survey.
IX. The Leo region H I catalog, group membership, and the H I mass function for
the Leo I group.
Stierwalt S., Haynes M.P., Giovanelli R., Kent B.R., Martin A.M.,
Saintonge A., Karachentsev I.D., Karachentseva V.E.
<Astron. J., 138, 338-361 (2009)>
=2009AJ....138..338S 2009AJ....138..338S
ADC_Keywords: Surveys; H I data ; Galaxies, radio ; Redshifts
Keywords: galaxies: distances and redshifts - galaxies: dwarf -
galaxies: evolution - galaxies: formation - galaxies: halos -
galaxies: luminosity function, mass function - radio lines: galaxies
Abstract:
We present the catalog of HI sources extracted from the ongoing
Arecibo Legacy Fast ALFA (ALFALFA) extragalactic HI line survey,
found within the sky region bounded by 9:36<RA<11:36 and +08<DE<+12.
The HI catalog presented here for this 118deg2 region is combined
with the ones derived from surrounding regions also covered by the
ALFALFA survey to examine the large-scale structure in the complex Leo
region. Because of the combination of wide sky coverage and superior
sensitivity, spatial and spectral resolution, the ALFALFA HI catalog
of the Leo region improves significantly on the numbers of low HI mass
sources as compared with those found in previous HI surveys.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 101 549 HI Candidate Detections
notes.dat 80 138 Individual notes
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See also:
J/AJ/130/2613 : 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)
J/AJ/136/713 : Arecibo legacy Fast ALFA survey. VI (Kent+, 2008)
J/ApJS/183/214 : Arecibo Legacy Fast Alfa Survey. VIII (Martin+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [5-]
3- 5 I03 --- Seq [1/549] Source identification (5-NNN)
in Simbad
7- 12 I6 --- AGC Arecibo General Catalog number
14- 15 I2 h RAh HI position Right Ascension (J2000) (1)
17- 18 I2 min RAm HI position Right Ascension (J2000) (1)
20- 23 F4.1 s RAs HI position Right Ascension (J2000) (1)
25 A1 --- DE- HI position Declination sign (J2000) (1)
26- 27 I2 deg DEd HI position Declination (J2000) (1)
29- 30 I2 arcmin DEm HI position Declination (J2000) (1)
32- 33 I2 arcsec DEs HI position Declination (J2000) (1)
35- 36 I2 h RAOh ? Optical position Right Ascension (J2000) (2)
38- 39 I2 min RAOm ? Optical position Right Ascension (J2000) (2)
41- 44 F4.1 s RAOs ? Optical position Right Ascension (J2000) (2)
46 A1 --- DEO- Optical position Declination sign (J2000) (2)
47- 48 I2 deg DEOd ? Optical position Declination (J2000) (2)
50- 51 I2 arcmin DEOm ? Optical position Declination (J2000) (2)
53- 54 I2 arcsec DEOs ? Optical position Declination (J2000) (2)
56- 60 I5 km/s cz Heliocentric velocity of HI source (3)
62- 64 I3 km/s W50 Line profile at 50% level velocity width (4)
66- 68 I3 km/s e_W50 Error in W50 (4)
70- 74 F5.2 Jy.km/s Fc Integrated line flux (5)
76- 80 F5.1 --- S/N Signal-to-noise (6)
82- 85 F4.2 mJy rms Spatially integrated spectral profile noise
figure (7)
87- 91 F5.1 Mpc Dist ? Adopted distance (8)
93- 97 F5.2 [Msun] logM ? Log of the HI mass (9)
99 I1 --- Code [1/9] Object code (10)
101 A1 --- Note [*] * indicates a note in notes.dat file
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Note (1): Centroid position after correction for systematic telescope pointing
errors (see Kent et al. (2008AJ....136..713K 2008AJ....136..713K) for a description of how
pointing errors vary with declination for the Arecibo telescope). The
accuracy of HI positions depends on source strength.
Note (2): Centroid position of the optical galaxy found to provide the most
reasonable optical counterpart to the HI detection. Assignments of optical
identifications are made via the Skyview website and are based on spatial
proximity, morphology, color, and redshift. Accuracy of centroids is
estimated to be ≤25". For cases with lacking or ambiguous optical
counterparts, comments are provided as alerted by an asterisk in the
"Code" column.
Note (3): Measured as the midpoint between the channels at which the flux
density drops to 50%. The error can be estimated as half the error on
the width.
Note (4): Corrections for broadening but not turbulent motions, disk
inclination, or cosmological effects are applied. The estimated error on the
velocity width is estimated by the sum in quadrature of two components: a
statistical error, principally dependent on the S/N ratio of the feature
measured, and a systematic error associated with the observer's subjective
guess at the quality of the chosen spectral extent of the feature. In the
majority of cases, the statistical error is significantly larger than the
systematic error; thus the latter is ignored.
Note (5): 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).
Note (6): S/N of the detection, as estimated by
S/N=(1000Fc/W50)ωsmo1/2/σrms,
where Fc is the integrated flux density, as listed in Column 7, the ratio
of 1000Fc/W50 is the mean flux across the feature in mJy, ωsmo,
the smoothing width expressed as the number of spectral resolution bins
of 10km/s bridging half of the signal width, is either W50/(2x10) for
W50<400km/s or 400/(2x10)=20 for W50≥400km/s, and σrms is the
rms noise figure across the spectrum measured in mJy at 10km/s resolution,
as tabulated in Column "rms".
Note (7): The noise figure 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 (8): For objects with czcmb>6000, the distance is simply czcmb/H0,
where 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
multiattractor, peculiar velocity model for the local Universe presented in
Masters (2005, PhD thesis, Cornell Univ). Objects which are thought to be
parts of clusters or groups (for group membership assignments Springob et al.
(2007, Cat. J/ApJS/172/599)) are assigned the czcmb of the cluster or group.
A detailed analysis of group and membership of Leo objects is presented in
Section 4.
Note (9): Obtained using MHI=2.356x105D2MpcFc.
Note (10): object code, defined as follows:
1 = refers to sources of S/N and general qualities that make it a reliable
detection: an approximate S/N threshold of 6.5, a good match between the
two independent polarizations, and a spatial extent consistent with the
characteristics of the telescope beam. Thus, some candidate detections
with S/N 6.5 have been excluded on grounds of polarization mismatch,
spectral vicinity to RFI features or peculiar spatial properties.
Likewise, some features of S/N<6.5 are included as reliable detections
if the source's optical characteristics clearly resemble typical
galaxies found at the redshift of the HI feature. We estimate that
detection candidates with S/N<6.5 in Table will be confirmed in
follow-up observations in better than 95% of cases (Saintonge,
2007AJ....133.2087S 2007AJ....133.2087S).
2 = refers to sources of low S/N (<6.5), which would ordinarily not be
considered reliable detections by the criteria set for code 1. However,
those HI candidate sources are matched with optical counterparts with
known optical redshifts which, within their respective errors, coincide
with those measured in the HI line. We refer to these sources
as "priors."
9 = refers to objects assumed to be high-velocity clouds (HVCs) based on
their low heliocentric velocities (<200km/s) and their lack of an
optical counterpart; no estimate for their distance is made.
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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 --- --- [5-]
3- 5 I03 --- Seq [1/549] Source identification (5-NNN)
7- 80 A74 --- Note Text of the note
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History:
* 13-Jul-2012: From electronic version of the journal
* 05-Nov-2013: Values 0 for optical position when no optical counterpart
suppressed
References:
Haynes et al., Paper I 2011AJ....142..170H 2011AJ....142..170H
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, 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
Martin et al., Paper VIII 2009ApJS..183..214M 2009ApJS..183..214M, Cat. J/ApJS/183/214
Martin et al., Paper X 2010ApJ...723.1359M 2010ApJ...723.1359M
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 29-Nov-2011