Green Bank Telescope Spectra

Documentation



glangsto -at- nrao.edu

created on:

2003MAR31

GBT Observations of W3 at 334 MHz, using the Spectral Processor for RFI excision. The images and plots below show that good quality continuum images are produced in the Spectral Processor with 20 MHz bandwidth and 1024 channels.

The data were examined, flagged, calibrated and imaged with AIPS++. The first images below show effects of flagging on the imaging process. The left image below shows the spectra before gridding in RA and Declination. The right image shows the location of the integrations in the 17 scans made to produce the image. The gaps in the scans correspond to times when strong broad band RFI was present.

A glish script is provided that allowes an observer to produce an AIPS++ image of these data.
Image of the raw Spectra for a spectral line map of W3. The horizontal axis is frequency (in channels) for 1024 channels in a 20 MHz band centered on 334 MHz. The vertical axis is time, where each spectrum is from a 10 second integration.

The white horizontal stripes show times when the telescope was observing the brightest parts of W3. The dark orange data show times when the telescope was pointed at the edges of W3.

The verticle purple lines show frequencies where RFI was flagged. The two horizontal purple lines show time ranges where broadband RFI was flagged.

Image of a 4 by 4 degree region containing W3. This image shows one channel of the spectral line cube produced from an average of 5 channels of data from the spectra at left. The center frequency 334 MHz and the bandwidth was 100 KHz. The image is produced using the high cal noise diode assuming an effective temperature of 1 K. The actual noise diode temperature was 29.3 K, so the image intensity should be scaled by a factor of 29.3.

The spectra were obtained in 10 second integrations while continuously slewing the telescope over the region at a rate of 2 degrees/minute. The colored dots show the average intensity for the 10 second integration, but the data were taken continuously while the 17 two minute scans were obtained.

Image of W3 produced with the normal imaging parameters, showing the effects of convolution on the missing spectral samples.

A glish script is provided that allowes the observer to quickly produce such an image.

W3 calibrated spectra obtained from the average of the 12 integrations in the first scan of the W3 map. Due to a configuration error, a noise diode value of 1 K is assumed for these spectra. The true noise diode value is 29.3 K
W3 calibrated spectra obtained from the average of the 12 integrations in the middle scan of the W3 map. Due to a configuration error, a noise diode value of 1 K is assumed for these spectra. The true noise diode value is 29.3 K
W3 raw uncalibrated spectra obtained while pointing 2 degrees away from the center of W3. Ascii Data (2003_03_14_00:47:35.7.log)
W3 calibrated dual circular polarization spectra obtained while pointed 2 degrees away from the center of W3. Data were noise diode calibrated using an equivalent noise diode temperature of 29.3 K for both Left and Right Circular polarizations.

These spectra are the average of 12 ten second integrations.

The verticle spikes show the bright RFI features. Fainter RFI features are found a few MHz on either side of the RFI spikes. Ascii Data (2003_03_14_00:47:35.9.log)

W3 calibrated dual circular polarization spectra obtained while pointed twoards the center of W3. Data were "Tsys (On-Off)/Off" calibrated assuming an Off source system temperature of 145 K for LCP and 109 K for RCP.

These spectra are the average of 12 ten second integrations.

The verticle spikes show the bright RFI features. Fainter RFI features are found a few MHz on either side of the RFI spikes.

Ascii Data (2003_03_14_00:48:53.11.log)

Observing Setup

These data were obtained by Commissars/Langston using the GBT. The observing project was 'T_PF1_03MAR13' and observation ID was 'test'. Object 'W3' was observed on 2003MAR14. The Rest Frequency was 334.000000 (MHz).

Data were written to directory:
/home/gbtdata/T_PF1_03MAR13

Modified on 2003-May-14