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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
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:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 101 549 HI Candidate Detections notes.dat 80 138 Individual notes
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
Bytes Format Units Label Explanations
1- 2 A2 --- --- [5-] 3- 5 I03 --- Seq [1/549] Source identification (5-NNN) <ALFALFA 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 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
Note (1): Centroid position after correction for systematic telescope pointing errors (see Kent et al. (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). Note (6): S/N of the detection, as estimated by S/N=(1000Fc/W50)ωsmo1/2rms, 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). 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.
Byte-by-byte Description of file: notes.dat
Bytes Format Units Label Explanations
1- 2 A2 --- --- [5-] 3- 5 I03 --- Seq [1/549] Source identification (5-NNN) 7- 80 A74 --- Note Text of the note
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 Giovanelli et al., Paper II 2005AJ....130.2613G, Cat. J/AJ/130/2613 Giovanelli et al., Paper III 2007AJ....133.2569G, Cat. J/AJ/133/2569 Saintonge, Paper IV 2007AJ....133.2087S Saintonge et al., Paper V 2008AJ....135..588S, Cat. J/AJ/135/588 Kent et al., Paper VI 2008AJ....136..713K, Cat. J/AJ/136/713 Kent et al., Paper VII 2009ApJ...691.1595K Martin et al., Paper VIII 2009ApJS..183..214M, Cat. J/ApJS/183/214 Martin et al., Paper X 2010ApJ...723.1359M
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 29-Nov-2011
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