GBT Commissioning Logs and Summary from 01 Feb 05 to 01 Feb 21

This web page contains some techincal archives describing the first commissioning observations with the newly dedicated Robert C. Byrd Green Bank Telescope. Selected images from the commissioning observations are available below. These data are public domain, but the data calibration reliability is poor.

A log of recent observations is online.

The commissioning summaries and beam map images are presented below:
Image
DateFrequencyNote
(UTC)(GHz)
3C147 Scan 1 2001 Feb 050.8 Prime Focus Observations. First commissioning Observations with the GBT. Source 3C147 is clearly visible in the center of this scan along a line of constant declination. This scan was plotted using AIPS++.

An image of this scan is also available.
3C295 Cross 2001 Feb 060.8 Prime Focus Observations. The image at left shows source 3C295 at the center of the cross scans along lines of constant Right Ascention and Declination. The second offset peak along the line of constant declination is due to Radio Frequency Interference (RFI).

In this image, red indicates more intense emission, green indicates regions of less emission and blue/black indicates least emission. The image at left has 1 arc minute square pixels. The image is made of 'I' polarization, by combining the two circular polarization IF's. Note that for the first few days, the circular and linear polarization data were flipped. The intensity scale is in units of T-cal. so to convert to Kelvins, the image must be multiplied by the effective temperature of the Cal signal, approximately 2 Kelvins.

2001 Feb 070.8 Prime Focus Observations.
2001 Feb 080.8 Prime Focus Observations.
2001 Feb 090.8 Prime Focus Observations. Problems prevented any observations this night.
2001 Feb 130.8 Prime Focus Observations.
3C147 Map 2001 Feb 140.8 Prime Focus Observations. 3C147 and 3C295 beam maps. Data are gridded to show serious RFI problems. The source 3C147 is in the center of this image. Raster scans are made along lines of constant declination.

An identically shaped 5 GHz NVSS Image is available for comparision. Note that several of the fainter components near 3C147 appear to be sources, not sidelobes.

2001 Feb 150.8 Prime Focus Observations. M&C FITS file scan numbers correct. Before this night, the Scan Logs and Fits files have inconsistent scan number. The source of the RFI was found to be space heaters on the GBT site. These were turned off and the problems cleared.
Virgo A 2001 Feb 160.8 Prime Focus Observations. Virgo A Beam Maps. Image peaks are satureated. A second image of Virgo was made.

An identically shaped 5 GHz NVSS Image is available for comparision.

3C147 2001 Feb 170.8 Prime Focus Observations. 3C147 Beam Maps. The sense of the 800 MHz polarization switch is correct in these observations, and I polarization images are produced from the combination of X and Y linear polarization data. The data are gridded so that the individual points in the scans are visible. These observations were made before the hysteresis effect (due to a time tag error) was fixed.
3C295 2001 Feb 210.8 Prime Focus Observations. 3C147 and 295 Beam Maps. Note that for the image at left, the time tag errors are still present in the raw DCR data, but the time tages have been corrected when combined with the antenna pointing data. The adjacent scans are well matched and there is very little RFI. A smooth version of the image at left was used to measure the ratio of the peak to first side lobe. There is a peak to the south west of the main peak, with height of 1 T-Cal. The source peak is 19 T-Cal.

The National Radio Astronomy Observatory (NRAO) is a facillity of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

glangsto@nrao.edu, last update: 2001 March 23