Green Bank Telescope Spectra /tmp/2002JAN25-4h24m/2002JAN25.html

On 2002 January 23, observations of bright radio source 3C286 were made in the frequency range 690 to 910 MHz using the GBT and spectrometer. The data were taken in 50 MHz frequency bands, in dual polarization.

The plots below show 5 minutes of data on 3C286 calibrated by subtraction of 5 minutes of off source data, then division by the off source spectra. The an off source system temperature of 20 K was assumed for these observations.

Uncalibrated observations of radio source 3C286. Showing the relative gain of the GBT system as a function of frequency (X axis). This plot shows dual polarization observations of the two cal states of linear polarization observations at 800 MHz.
2002_01_24_06:56:10A.0.ps

Uncalibrated observations of radio source 3C286. Showing the relative gain of the GBT system as a function of frequency (X axis).
The X linear polarization channel shows a 12.5 MHz band pass filter in band, because of a failure of the 50 MHz filter.
2002_01_24_06:56:10A.1.ps

Uncalibrated observations of radio source 3C286. Showing the relative gain of the GBT system as a function of frequency (X axis).
2002_01_24_06:56:10A.2.ps

Uncalibrated observations of radio source 3C286. Showing the relative gain of the GBT system as a function of frequency (X axis).
2002_01_24_06:56:10A.3.ps

Calibrated observations of radio source 3C286. Showing spectral shape of the radio source and several RFI features.
The calibration was performed by subtracting a 5 minute off source observation from a 5 minute on source observation, then dividing by the off source spectra. The intensity scale (Y axis) was set assuming the off source system temperature was 20 K. Only a single (Y linear) polarization is shown, but for both cal on and cal off spectra.
2002_01_24_06:43:55A.4.ps

3C286: 326; OffOn 1/2
(Plot - Off) / Off (1)
2002_01_24_06:38:35A.5.ps

Calibrated spectra of bright radio source 3C286. The deep notch at 796 MHz is due to the "Ortho-mode-transducer" in the receiver feed, which has low gain at resonant frequencies.
2002_01_24_06:43:55A.6.ps

Calibrated spectra of bright radio source 3C286. The deep notch at 817.5 MHz is due to the "Ortho-mode-transducer" in the receiver feed, which has low gain at resonant frequencies.
Also note the 10 % absorption feature at 839.4 MHz.
2002_01_24_06:43:55A.7.ps

Same spectrum as above, except zoomed in on 839.5 MHz center frequency. Calibrated observations of radio source 3C286. Showing a high redshift neutral hydrogen absorption feature.
2002_01_24_06:43:55A.8.ps

Same spectrum as above, except zoomed in further on 839.5 MHz center frequency. Calibrated observations of radio source 3C286. Showing a high redshift neutral hydrogen absorption feature. The 3C286 intensity has been subtracted using a linear baseline fit. The absorption feature is approximately 10 % of the 3C286 source brightness.
The GBT is a facility of the National Science Foundation

last modified on: 2002JAN25

	Uncalibrated observations of radio source 3C286. Showing the relative gain of the GBT system as a function of frequency (X axis). This plot shows dual polarization observations of the two cal states of linear polarization observations at 800 MHz. 2002_01_24_06:56:10A.0.ps
	Uncalibrated observations of radio source 3C286. Showing the relative gain of the GBT system as a function of frequency (X axis). The X linear polarization channel shows a 12.5 MHz band pass filter in band, because of a failure of the 50 MHz filter. 2002_01_24_06:56:10A.1.ps
	Uncalibrated observations of radio source 3C286. Showing the relative gain of the GBT system as a function of frequency (X axis). 2002_01_24_06:56:10A.2.ps
	Uncalibrated observations of radio source 3C286. Showing the relative gain of the GBT system as a function of frequency (X axis). 2002_01_24_06:56:10A.3.ps
	Calibrated observations of radio source 3C286. Showing spectral shape of the radio source and several RFI features. The calibration was performed by subtracting a 5 minute off source observation from a 5 minute on source observation, then dividing by the off source spectra. The intensity scale (Y axis) was set assuming the off source system temperature was 20 K. Only a single (Y linear) polarization is shown, but for both cal on and cal off spectra. 2002_01_24_06:43:55A.4.ps
	3C286: 326; OffOn 1/2 (Plot - Off) / Off (1) 2002_01_24_06:38:35A.5.ps
	Calibrated spectra of bright radio source 3C286. The deep notch at 796 MHz is due to the "Ortho-mode-transducer" in the receiver feed, which has low gain at resonant frequencies. 2002_01_24_06:43:55A.6.ps
	Calibrated spectra of bright radio source 3C286. The deep notch at 817.5 MHz is due to the "Ortho-mode-transducer" in the receiver feed, which has low gain at resonant frequencies. Also note the 10 % absorption feature at 839.4 MHz. 2002_01_24_06:43:55A.7.ps
	Same spectrum as above, except zoomed in on 839.5 MHz center frequency. Calibrated observations of radio source 3C286. Showing a high redshift neutral hydrogen absorption feature. 2002_01_24_06:43:55A.8.ps
	Same spectrum as above, except zoomed in further on 839.5 MHz center frequency. Calibrated observations of radio source 3C286. Showing a high redshift neutral hydrogen absorption feature. The 3C286 intensity has been subtracted using a linear baseline fit. The absorption feature is approximately 10 % of the 3C286 source brightness.