The ALFALFA Catalog Data

All sources have been extracted from three-dimensional spectral data cubes exploiting a matched filtering technique and then examined interactively to yield global HI parameters. Catalog details can be found in the first ALFALFA catalog paper Giovanelli et al. 2007 AJ 133, 2559 which describes the survey and how the catalogues are constructed.

Catalog Contents
	Variable Name	Format	Data Content

	  Object	  A17	  A temporary entry identifier for this Catalog. Note:
                                  Since the astrometry may be updated after the source is extracted,
                                  this designation is for INTERNAL PURPOSES only!
	  AGC		  A6	  The source number in the AGC, a private database
 				  of extragalactic objects maintained by M.P.H. and 
				  R.G. The AGC entry normally correspnds to the optical 
				  counterpart except in the cases of HI sources that 
				  cannot be associated with and optical object with any 
				  high degree of probability.
	  Other		  A8	  Alternative source name.
	  Ellipse Center  A15	  Center (J2000) of the ellipse bounding the HI source after 	
				  correction for systematic telescope pointing errors, with a 
				  range between a few and about a dozen arcseconds. On average, 
				  the positional accuracy is about 24". Measured in RA and DEC, 
				  where the units of right ascension are hours, minutes, and 	
				  seconds, and units of declination are degrees, arcminutes, 
				  and arcseconds.
	  dRA		  I3	  Difference in the degrees RA of the Ellipse Center and the 
				  Optical Center.
	  dDEC		  I3	  Difference in the degrees DEC of the Ellipse Center and the 
				  Optical Center.
	  Optical Center  A15	  Center (J2000.0) of the optical galaxy found to provide a 
				  reasonable optical counterpart. For objects with no 
				  discernible optical counterpart and those for which such 
				  assignment is ambiguous, due to the presence of more than 
				  one equally possible optical counterpart, no optocal 
				  position is listed. The latter set includes HVCs.
	  hSize		  F3.1
	  v50		  I5	  Heliocentric velocity, in km/s, of the HI source 
				  measured as the midpoint between the channels at 
 				  which the flux density drops to 50% of the two peaks.
	  Verr		  I2	  The error of v50 adopted as half the error on the 
				  width, tabulated in W50
	  W50		  I3	  Velocity width of the source line profile, W50, 
				  measured at 50% level of each two peaks.
	  Werr		  I3	  Error in W50 measured as 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.
	  SintP		  F5.2	  Integrated HI line flux density in Jy-km/s
	  Serr		  F4.2	  Error of the integrated flux density.
	  Sintmap	  F5.2    (in general, not of use)
	  S/N		  F5.1	  S/N of the detection
	  rms		  F4.2	  Noise figure of the spatially integrated spectral 
				  profile in mJy. The noise figure as tabulated is 
				  the rms and measured over the signal- and RFI-free 
				  portions of the spectrum, after Hanning smooting to 
				  a spectral resolution of 10 km/s
	  code		  I1	  Object code defined as follows:
				  Code 1 refers to sources of S/N and general quantities 
				  that make it a reliable detection.
				  Code 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.
				  Code 9 refers to objects assumed to be HVC's; no 
				  estimate of their distances is made.
	  Grid		  A8	  grid of pre-processed raw data on which the source can
				  be found.

ALFALFA Catalog records are now 156 characters in length:

This page maintained by members of the Cornell ExtraGalactic Group.

Last modified: Fri Jun 24 18:06:37 EDT by martha