GBT HI Galaxy Survey Line Profile Index

The following is a list of galaxies in the GBT HI galaxy survey observing list. This survey has been a background task during telescope commissioning. Objects for which the data have been reduced are marked with asterisks and have active links to the spectrum displays and associated data.

At the top of each galaxy's web page is a table of observing parameters for the displayed data. The decimal R.A. and Declination coordinates are J2000 for the "on" scan direction. The azimuth, zenith distance date and UTC refer to the center of the first scan. The UTC is in fraction of a day. The Doppler correction is the radial component of the earth's motion with respect to the solar system barycenter in the direction of the object a fraction of the speed of light. The effective integration is the total on-source time less any data deleted as bad. The off-source time is the same.

A plot of the unedited spectrum is shown for all galaxies. If any data were deleted because of interference or bad baselines in some one-minute records, a full edited spectrum is also shown. If a measurable profile was detected, the portion of the spectrum around the profile is shown with markers for the chosen peak intensity, 20% peak intensity profile edge points, and the velocity range over which the flux density integral was computed. All of these values and ranges were measured or selected manually. The flux density was computed from the data for the selected range. In the case of double-peaked profiles, the peak value chosen was the average of the two peak intensities. Before the profile was measured a baseline (usually second order as noted in the text) was removed from the unedited or edited spectrum. The ranges used to solve for this baseline were selected by hand to avoid any interference or edge of band distortions. If any interference spikes fell within the flux integral velocity range, they were remove by interpolation before the profile was measured.

At the bottom of each detected galaxy's web page the measured profile parameters are listed. Most of the values are self-explanatory. Three values for the profile flux density integral are given, one each for receiver channels 1 and 2 (labeled A and B) plus the combined measurement using the best estimate of the intensity calibration ratio of the two channels in each case. Channel 2 (B) is generally the most reliable so the combined flux density integral with generally agree with it fairly closely. Since the measured ratios of the channel 1 and 2 flux integrals were used in an aggregate sense to determine the relative calibration of the two channels over several or more days of observations, the measured ratio is given for each galaxy in the web page table.

A summary table of all measured galaxy profile data can be found in an ASCII file. ASCII files containing the frequency, velocity, and intensity values for the full spectra used in the profile measurements can be ftp'd from the anonymous ftp account of The files are named by object name and scan number. The data in these files are in the format

    frequency table in MHz
    velocity table in km/s
    number of 1-munute spectra in channel 1 spectrum
    channel 1 spectrum intensity table in Jy
    number of 1-munute spectra in channel 2 spectrum
    channel 2 spectrum intensity table in Jy

Last modified June 3, 2003

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