J/AJ/130/2613 The Arecibo Legacy Fast ALFA survey. II (Giovanelli+, 2005)
The Arecibo Legacy Fast ALFA survey. II. Results of precursor observations.
Giovanelli R., Haynes M.P., Kent B.R., Perillat P., Catinella B.,
Hoffman G.L., Momjian E., Rosenberg J.L., Saintonge A., Spekkens K.,
Stierwalt S., Brosch N., Masters K.L., Springob C.M., Karachentsev I.D.,
Karachentseva V.E., Koopmann R.A., Muller E., van Driel W., van Zee L.
<Astron. J., 130, 2613-2624 (2005)>
=2005AJ....130.2613G 2005AJ....130.2613G
ADC_Keywords: H I data
Keywords: galaxies: distances and redshifts - galaxies: halos -
galaxies: luminosity function, mass function - galaxies: photometry -
galaxies: spiral - radio lines: galaxies
Abstract:
In preparation for the full Arecibo Legacy Fast ALFA (ALFALFA)
extragalactic HI survey, precursor observations were carried out in
2004 August-September with the seven-beam Arecibo L-band Feed Array
(ALFA) receiver system and the Wideband Arecibo Pulsar Processor
spectral processors. While these observations were geared mainly at
testing and debugging survey strategy, hardware, and software,
approximately 48hr of telescope time yielded science-quality data. To
test our ability to discriminate cosmic signals from radio-frequency
interference and noise, 165 candidates ranging in reliability
likelihood were reobserved with the single-beam L-band wide system at
Arecibo in 2005 January-February. Of those, 41% were confirmed as
real. We present the results of both the ALFA and the single-beam
observations for the sample of 166 confirmed HI sources, as well as
our assessment of their optical counterparts.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 71 166 Parameters of ALFA (L-band Feed Array) detections
table3.dat 77 68 *Parameters of LBW (L-band wide) detections
table4.dat 66 166 Optical ID, distances and HI masses
notes.dat 80 171 Notes
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Note on table3.dat : HI 010225.7+263613 is a misprint for HI 010225.7+263713.
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See also:
VIII/73 : HI Parkes All Sky Survey Catalogue (HIPASS) (Meyer+, 2004)
J/MNRAS/342/738 : HI Jodrell All Sky Survey (Lang+, 2003)
J/ApJS/130/177 : Arecibo Dual-Beam Survey (Rosenberg+, 2000)
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)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [HI]
4- 18 A15 --- HI Source identification (G1)
20- 23 F4.1 s e_RA ? Estimated Right Ascension centroid
position error
25- 26 I2 arcsec e_DE ? Estimated Declination centroid
position error
28- 32 I5 km/s cz Center heliocentric velocity of the feature
34- 35 I2 km/s e_cz Estimated measurement error in cz
37- 38 I2 km/s ecz Systematic component error in cz (G2)
40- 42 I3 km/s W ? Velocity width of spectral feature (G3)
44- 46 I3 km/s e_W ? Estimated error in W (G4)
48- 51 F4.2 mJy rms RMS of composite HI spectrum (G5)
53- 57 F5.2 Jy.km/s Fc Spectral feature flux integral
59- 62 F4.2 Jy.km/s e_Fc Statistical error in Fc (G6)
64- 68 F5.2 Jy.km/s Fm ? Spectral feature flux integral obtained
from map (1)
70 A1 --- LBW [L] detection corroborated with LBW (2)
71 A1 --- Note [*] Additional notes detailed in notes.dat
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Note (1): For cases for which the ALFA data indicate significant angular
extent of the HI source, this is an estimate of the total flux of the
source derived from a map. Note that for the majority of sources the
signal-to-noise ratio is not sufficient to obtain a reliable map.
Note (2): the 'L' indicates that the ALFA detection is corroborated by
observations with the LBW single-pixel feed. The results of those
observations are given in Table 3.
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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- 2 A2 --- --- [HI]
4- 18 A15 --- HI Source identification (G1)
20- 21 I2 h RAh Hour of Right Ascension (J2000)
23- 24 I2 min RAm Minute of Right Ascension (J2000)
26- 29 F4.1 s RAs Second of Right Ascension (J2000)
31 A1 --- DE- Sign of the Declination (J2000)
32- 33 I2 deg DEd Degree of Declination (J2000)
35- 36 I2 arcmin DEm Arcminute of Declination (J2000)
38- 39 I2 arcsec DEs Arcsecond of Declination (J2000)
41- 45 I5 km/s cz Center heliocentric velocity of the feature
47- 48 I2 km/s e_cz Estimated measurement error in cz
50- 52 I3 km/s ecz Systematic component of error in cz (G2)
54- 56 I3 km/s W Velocity width of spectral feature (G3)
58- 60 I3 km/s e_W Estimated error in W (G4)
62- 65 F4.2 mJy rms RMS of LBW HI spectrum (G5)
67- 70 F4.2 Jy.km/s Fc Spectral feature flux integral
72- 75 F4.2 Jy.km/s e_Fc Statistical error in Fc (G6)
77 A1 --- Note [*] Indicates comments available in notes.dat
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [HI]
4- 18 A15 --- HI Source identification (G1)
20- 25 I6 --- AGC Arecibo General Catalog identification (1)
27- 28 I2 h RAo.h ? Hour of Right Ascension (J2000) (2)
30- 31 I2 min RAo.m ? Minute of Right Ascension (J2000) (2)
33- 36 F4.1 s RAo.s ? Second of Right Ascension (J2000) (2)
38 A1 --- DEo.- Sign of the Declination (J2000) (2)
39- 40 I2 deg DEo.d ? Degree of Declination (J2000) (2)
42- 43 I2 arcmin DEo.m ? Arcminute of Declination (J2000) (2)
45- 46 I2 arcsec DEo.s ? Arcsecond of Declination (J2000) (2)
48- 52 F5.1 Mpc Dcmb ? CMB distance assuming pure Hubble flow (3)
54- 58 F5.1 Mpc Dpec Distance corrected for peculiar velocity (4)
60- 64 F5.2 [solMass] MHI Log of the HI mass (5)
66 A1 --- Note [*] Indicates comments available in notes.dat
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Note (1): AGC numbers smaller than 13000 coincide with those of the
Uppsala General Catalog (Nilson 1973, Cat. VII/26).
Note (2): Of the proposed optical counterpart of the HI source.
These coordinates are either obtained from previous tabulations or
directly measured using the Skyview facility. Positional accuracies
are of order 1".
Note (3): Obtained from the radial velocity corrected to the Cosmic
Microwave Background rest frame, and assuming pure Hubble flow
with H0=70km/s/Mpc.
Note (4): Obtained from the measured redshift and from the peculiar
velocity field model of Tonry et al. (2000ApJ...530...62G 2000ApJ...530...62G), for
H0=70km/s/Mpc. In addition to the error on the measurement of
cz and the systematics in the flow model (see Masters, 2005, Ph.D.
thesis, Cornell Univ.), a "thermal" velocity component of 187km/s
as assumed by Tonry et al. (2000ApJ...530...62G 2000ApJ...530...62G) introduces an
additional uncertainty of 2.7Mpc on each distance estimate.
Note (5): Via MHI=2.356x105Dpec2F, where Dpec is the distance in Mpc
and F is the flux integral obtained from Fm (or Fc if Fm is blank)
of Table 2.
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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 --- --- [HI]
4- 18 A15 --- HI Source identification
20- 80 A61 --- Note Note
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Global Notes:
Note (G1): Source identification, composed of the qualifier 'HI' and
the RA and DE (epoch J2000.0) of the HI centroid.
Note (G2): When two non zero numbers are listed for e_cz and f_cz, the
second is an estimate of the systematic component of the error, while
the first is a statistical error which depends on the shape of the
signal and the signal-to-noise. The systematic error results from the
observer's subjective choice of the signal boundaries: when those are
clear, the systematic error is nil; when strong uncertainty exists in
making that choice, a visual guess is made by the observer of the
potential amplitude of the uncertainty. The total error on cz is the
sum in quadrature of the two components of the error.
Note (G3): Measured at 50% level of intensity of two peaks on each side of
the signal. Widths are corrected for instrumental smoothing and
relativistic broadening, i.e. the tabulated values are
(Wmeasured2-res2)-1/2/(1+z), where res is the spectral
resolution in km/s. No disk inclination nor turbulent motion
correction is applied to the widths.
Note (G4): Note that the measurement error on the width is effectively a
fractional error, so that W(e_W)=100(50) should be read as
100+50-33.
Note (G5): Measured "locally", i.e. over a baseline region within 10MHz of
the detected feature rather than over the full spectrum.
Note (G6): Compounded with the overall uncertainty on the flux calibration.
This value is an underestimate of the true flux if the source is
extended in comparison with the beam size.
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History:
From electronic version of the journal
References:
Giovanelli et al., Paper I 2005AJ....130.2598G 2005AJ....130.2598G
(End) Greg Schwarz [AAS], Marianne Brouty [CDS] 04-Aug-2006