12 Meter Telescope - Telescope Efficiencies

The following table contains the most recent measured telescope efficiencies. The definitions for $eta$ ^*_m and $eta$ _mb are...

$eta$ ^*_m is the "corrected main beam efficiency", which is used to convert from the $T$ ^*_R temperature scale to the main beam brightness temperature scale ( $T$ _mb). The corrected main beam efficiency is the fraction of the forward power in the main diffraction beam relative to the total forward power in the main beam plus error beam.
$eta$ _mb is the "main beam efficiency", which is used to convert from the $T$ ^*_A temperature scale to the main beam brightness temperature scale ( $T$ _mb).
$eta$ _mb/(eta_leta_fss) = $eta$ ^*_m

eta

_l = 0.94 (the rear scattering, spillover, and radiative loss efficiency) and

eta

_fss = 0.68 (the forward scattering and spillover efficiency), independent of frequency.

The following tables are ordered by frequency for a given year. Efficiencies for 1995, 1996, 1997, 1998, 1999, and 2000 are tabulated. A plot of these efficiency measurements compared to a theoretical estimate of

eta

^*_m based on the Ruze equation (see the User's Manual for details) is given here. I have also made plots of planet equatorial diameter as a function of day number for 1998, 1999, and 2000 to be used as an aid in calculating efficiencies and for determining which planets can be used as calibrators. Efficiencies are also tabulated for the 1mm Array Receiver.

NRAO 12m Telescope Efficiencies for 2000
Frequency (GHz)	Source	Source Size (arcsec)	eta^*_m	eta_mb	Date Measured
115.3	Saturn	18.9 x 17.2	0.84+-0.07	0.54+-0.043	January 2000

NRAO 12m Telescope Efficiencies for 1999

Frequency (GHz) Source Source Size (arcsec) eta^*_m eta_mb Date Measured

244.9 Mars 11.5 x 11.5 0.45+-0.05 0.29+-0.03 March 1999

NRAO 12m Telescope Efficiencies for 1999
Frequency (GHz)	Source	Source Size (arcsec)	eta^*_m	eta_mb	Date Measured
244.9	Mars	11.5 x 11.5	0.45+-0.05	0.29+-0.03	March 1999

NRAO 12m Telescope Efficiencies for 1998

Frequency (GHz) Source Source Size (arcsec) eta^*_m eta_mb Date Measured

220.0 Saturn 19.5 x 17.7 0.46+-0.03 0.29+-0.05 December 1998

225.0 Venus 42.5 x 42.5 0.52+-0.10 0.33+-0.06 February 1998

240.0 Mars 4.9 x 4.9 0.47+-0.02 0.30+-0.01 November 1998

NRAO 12m Telescope Efficiencies for 1998
Frequency (GHz)	Source	Source Size (arcsec)	eta^*_m	eta_mb	Date Measured
220.0	Saturn	19.5 x 17.7	0.46+-0.03	0.29+-0.05	December 1998
225.0	Venus	42.5 x 42.5	0.52+-0.10	0.33+-0.06	February 1998
240.0	Mars	4.9 x 4.9	0.47+-0.02	0.30+-0.01	November 1998

NRAO 12m Telescope Efficiencies for 1997

Frequency (GHz) Source Source Size (arcsec) eta^*_m eta_mb Date Measured

72.0 Jupiter 37.4 x 35.0 1.04+-0.13 0.66+-0.08 April 1997

98.0 Mars 8.5 x 8.4 0.83+-0.07 0.53+-0.04 June 1997

98.0 Saturn 16.9 x 15.3 0.93+-0.11 0.59+-0.08 June 1997

147.0 Jupiter 37.4 x 35.0 0.85+-0.10 0.54+-0.06 April 1997

172.5 Jupiter 37.4 x 35.0 0.79+-0.05 0.50+-0.02 April 1997

225.0 Venus 35.7 x 35.7 0.42+-0.03 0.27+-0.02 December 1997

225.0 Jupiter 36.9 x 34.5 0.56+-0.06 0.35+-0.04 December 1997

225.0 Saturn 18.9 x 17.1 0.46+-0.03 0.29+-0.02 December 1997

241.9 Mars 14.1 X 14.1 0.46+-0.02 0.29+-0.01 March 1997

251.9 Jupiter 34.6 X 32.4 0.50+-0.01 0.32+-0.01 March 1997

291.2 Saturn 18.4 X 16.7 0.29+-0.01 0.18+-0.01 December 1997

291.2 Saturn 18.4 X 16.7 0.34+-0.03 0.22+-0.02 December 1997

291.2 Saturn 18.4 X 16.7 0.41+-0.05 0.26+-0.03 December 1997

NRAO 12m Telescope Efficiencies for 1997
Frequency (GHz)	Source	Source Size (arcsec)	eta^*_m	eta_mb	Date Measured
72.0	Jupiter	37.4 x 35.0	1.04+-0.13	0.66+-0.08	April 1997
98.0	Mars	8.5 x 8.4	0.83+-0.07	0.53+-0.04	June 1997
98.0	Saturn	16.9 x 15.3	0.93+-0.11	0.59+-0.08	June 1997
147.0	Jupiter	37.4 x 35.0	0.85+-0.10	0.54+-0.06	April 1997
172.5	Jupiter	37.4 x 35.0	0.79+-0.05	0.50+-0.02	April 1997
225.0	Venus	35.7 x 35.7	0.42+-0.03	0.27+-0.02	December 1997
225.0	Jupiter	36.9 x 34.5	0.56+-0.06	0.35+-0.04	December 1997
225.0	Saturn	18.9 x 17.1	0.46+-0.03	0.29+-0.02	December 1997
241.9	Mars	14.1 X 14.1	0.46+-0.02	0.29+-0.01	March 1997
251.9	Jupiter	34.6 X 32.4	0.50+-0.01	0.32+-0.01	March 1997
291.2	Saturn	18.4 X 16.7	0.29+-0.01	0.18+-0.01	December 1997
291.2	Saturn	18.4 X 16.7	0.34+-0.03	0.22+-0.02	December 1997
291.2	Saturn	18.4 X 16.7	0.41+-0.05	0.26+-0.03	December 1997

NRAO 12m Telescope Efficiencies for 1996

Frequency (GHz) Source Source Size (arcsec) eta^*_m eta_mb Date Measured

98.0 Venus 12.2 X 12.2 0.90+-0.06 0.57+-0.04 November 1996

98.0 Mars 6.2 X 6.2 0.95+-0.03 0.61+-0.02 November 1996

109.8 Venus 22.1 X 22.1 0.97+-0.04 0.62+-0.02 August 1996

109.8 Jupiter 43.4 X 40.6 0.97+-0.05 0.62+-0.03 August 1996

109.8 Saturn 19.2 X 17.3 0.97+-0.06 0.62+-0.04 August 1996

109.8 Saturn 19.2 X 17.3 0.97+-0.11 0.62+-0.07 November 1996

115.3 Jupiter 43.4 X 40.6 0.88+-0.04 0.56+-0.02 August 1996

115.3 Saturn 19.2 X 17.3 0.97+-0.06 0.62+-0.04 August 1996

140.8 Venus 13.4 X 13.4 0.73+-0.05 0.46+-0.03 November 1996

140.8 Mars 5.5 X 5.5 0.85+-0.07 0.54+-0.04 November 1996

140.8 Jupiter 35.5 X 33.2 0.82+-0.09 0.52+-0.06 November 1996

140.8 Saturn 19.2 X 17.3 0.94+-0.10 0.60+-0.06 August 1996

140.8 Saturn 19.1 X 17.2 0.92+-0.09 0.59+-0.06 November 1996

140.8 Uranus 3.5 X 3.5 0.80+-0.10 0.51+-0.06 November 1996

140.8 Neptune 2.2 X 2.2 0.76+-0.10 0.48+-0.06 November 1996

144.6 Saturn 17.4 X 15.7 0.76+-0.04 0.48+-0.03 June 1996

230.5 Saturn 19.5 X 17.6 0.43+-0.11 0.27+-0.07 October 1996

230.5 Uranus 3.6 X 3.5 0.46+-0.15 0.29+-0.09 October 1996

241.8 Mars 7.5 X 7.5 0.61+-0.02 0.39+-0.01 December 1996

244.9 Mars 7.5 x 7.5 0.57+-0.04 0.36+-0.03 December 1996

265.9 Mars 5.5 X 5.5 0.48+-0.03 0.30+-0.02 November 1996

265.9 Mars 6.5 X 6.4 0.43+-0.02 0.27+-0.01 December 1996

291.8 Mars 7.1 x 7.1 0.42+-0.04 0.27+-0.02 December 1996

291.8 Mars 6.5 X 6.4 0.37+-0.04 0.23+-0.02 December 1996

NRAO 12m Telescope Efficiencies for 1996
Frequency (GHz)	Source	Source Size (arcsec)	eta^*_m	eta_mb	Date Measured
98.0	Venus	12.2 X 12.2	0.90+-0.06	0.57+-0.04	November 1996
98.0	Mars	6.2 X 6.2	0.95+-0.03	0.61+-0.02	November 1996
109.8	Venus	22.1 X 22.1	0.97+-0.04	0.62+-0.02	August 1996
109.8	Jupiter	43.4 X 40.6	0.97+-0.05	0.62+-0.03	August 1996
109.8	Saturn	19.2 X 17.3	0.97+-0.06	0.62+-0.04	August 1996
109.8	Saturn	19.2 X 17.3	0.97+-0.11	0.62+-0.07	November 1996
115.3	Jupiter	43.4 X 40.6	0.88+-0.04	0.56+-0.02	August 1996
115.3	Saturn	19.2 X 17.3	0.97+-0.06	0.62+-0.04	August 1996
140.8	Venus	13.4 X 13.4	0.73+-0.05	0.46+-0.03	November 1996
140.8	Mars	5.5 X 5.5	0.85+-0.07	0.54+-0.04	November 1996
140.8	Jupiter	35.5 X 33.2	0.82+-0.09	0.52+-0.06	November 1996
140.8	Saturn	19.2 X 17.3	0.94+-0.10	0.60+-0.06	August 1996
140.8	Saturn	19.1 X 17.2	0.92+-0.09	0.59+-0.06	November 1996
140.8	Uranus	3.5 X 3.5	0.80+-0.10	0.51+-0.06	November 1996
140.8	Neptune	2.2 X 2.2	0.76+-0.10	0.48+-0.06	November 1996
144.6	Saturn	17.4 X 15.7	0.76+-0.04	0.48+-0.03	June 1996
230.5	Saturn	19.5 X 17.6	0.43+-0.11	0.27+-0.07	October 1996
230.5	Uranus	3.6 X 3.5	0.46+-0.15	0.29+-0.09	October 1996
241.8	Mars	7.5 X 7.5	0.61+-0.02	0.39+-0.01	December 1996
244.9	Mars	7.5 x 7.5	0.57+-0.04	0.36+-0.03	December 1996
265.9	Mars	5.5 X 5.5	0.48+-0.03	0.30+-0.02	November 1996
265.9	Mars	6.5 X 6.4	0.43+-0.02	0.27+-0.01	December 1996
291.8	Mars	7.1 x 7.1	0.42+-0.04	0.27+-0.02	December 1996
291.8	Mars	6.5 X 6.4	0.37+-0.04	0.23+-0.02	December 1996

NRAO 12m Telescope Efficiencies for 1995

Frequency (GHz) Source Source Size (arcsec) eta^*_m eta_mb Date Measured

218.2 Saturn 18.0 X 16.1 0.58+-0.03 0.37+-0.02 November 1995

290.6 Saturn 17.7 X 15.8 0.28+-0.02 0.18+-0.01 December 1995

NRAO 12m Telescope Efficiencies for 1995
Frequency (GHz)	Source	Source Size (arcsec)	eta^*_m	eta_mb	Date Measured
218.2	Saturn	18.0 X 16.1	0.58+-0.03	0.37+-0.02	November 1995
290.6	Saturn	17.7 X 15.8	0.28+-0.02	0.18+-0.01	December 1995

NRAO 12m Telescope Efficiencies for the 1mm Array Receiver

Frequency (GHz) Beam Source Source Size (arcsec) eta^*_m eta_mb Date Measured

230.0 1 Saturn 17.5 x 15.8 0.55+-0.11 0.35+-0.07 January 1998

230.0 2 Saturn 17.5 x 15.8 0.65+-0.13 0.41+-0.08 January 1998

230.0 3 Saturn 17.5 x 15.8 0.45+-0.09 0.29+-0.06 January 1998

230.0 4 Saturn 17.5 x 15.8 0.55+-0.11 0.35+-0.07 January 1998

230.0 5 Saturn 17.5 x 15.8 0.47+-0.09 0.30+-0.06 January 1998

230.0 6 Saturn 17.5 x 15.8 0.34+-0.07 0.22+-0.04 January 1998

230.0 7 Saturn 17.5 x 15.8 0.56+-0.11 0.36+-0.07 January 1998

230.0 8 Saturn 17.5 x 15.8 0.53+-0.10 0.34+-0.07 January 1998

230.0 1 Saturn 16.7 x 15.2 0.59+-0.06 0.38+-0.04 February 1998

230.0 2 Saturn 16.7 x 15.2 0.50+-0.07 0.32+-0.04 February 1998

230.0 3 Saturn 16.7 x 15.2 0.54+-0.07 0.34+-0.04 February 1998

230.0 4 Saturn 16.7 x 15.2 0.58+-0.07 0.37+-0.04 February 1998

230.0 5 Saturn 16.7 x 15.2 0.57+-0.07 0.36+-0.04 February 1998

230.0 6 Saturn 16.7 x 15.2 0.47+-0.13 0.30+-0.08 February 1998

230.0 7 Saturn 16.7 x 15.2 0.57+-0.07 0.36+-0.04 February 1998

230.0 8 Saturn 16.7 x 15.2 0.52+-0.07 0.33+-0.04 February 1998

230.0 1 Mars 5.0 x 5.0 0.42+-0.02 0.27+-0.01 November 1998

230.0 3 Mars 5.0 x 5.0 0.40+-0.02 0.25+-0.01 November 1998

230.0 4 Mars 5.0 x 5.0 0.46+-0.02 0.29+-0.01 November 1998

230.0 5 Mars 5.0 x 5.0 0.49+-0.03 0.31+-0.01 November 1998

230.0 6 Mars 5.0 x 5.0 0.38+-0.03 0.24+-0.01 November 1998

230.0 7 Mars 5.0 x 5.0 0.46+-0.02 0.29+-0.01 November 1998

230.0 8 Mars 5.0 x 5.0 0.51+-0.02 0.32+-0.01 November 1998

NRAO 12m Telescope Efficiencies for the 1mm Array Receiver
Frequency (GHz)	Beam	Source	Source Size (arcsec)	eta^*_m	eta_mb	Date Measured
230.0	1	Saturn	17.5 x 15.8	0.55+-0.11	0.35+-0.07	January 1998
230.0	2	Saturn	17.5 x 15.8	0.65+-0.13	0.41+-0.08	January 1998
230.0	3	Saturn	17.5 x 15.8	0.45+-0.09	0.29+-0.06	January 1998
230.0	4	Saturn	17.5 x 15.8	0.55+-0.11	0.35+-0.07	January 1998
230.0	5	Saturn	17.5 x 15.8	0.47+-0.09	0.30+-0.06	January 1998
230.0	6	Saturn	17.5 x 15.8	0.34+-0.07	0.22+-0.04	January 1998
230.0	7	Saturn	17.5 x 15.8	0.56+-0.11	0.36+-0.07	January 1998
230.0	8	Saturn	17.5 x 15.8	0.53+-0.10	0.34+-0.07	January 1998
230.0	1	Saturn	16.7 x 15.2	0.59+-0.06	0.38+-0.04	February 1998
230.0	2	Saturn	16.7 x 15.2	0.50+-0.07	0.32+-0.04	February 1998
230.0	3	Saturn	16.7 x 15.2	0.54+-0.07	0.34+-0.04	February 1998
230.0	4	Saturn	16.7 x 15.2	0.58+-0.07	0.37+-0.04	February 1998
230.0	5	Saturn	16.7 x 15.2	0.57+-0.07	0.36+-0.04	February 1998
230.0	6	Saturn	16.7 x 15.2	0.47+-0.13	0.30+-0.08	February 1998
230.0	7	Saturn	16.7 x 15.2	0.57+-0.07	0.36+-0.04	February 1998
230.0	8	Saturn	16.7 x 15.2	0.52+-0.07	0.33+-0.04	February 1998
230.0	1	Mars	5.0 x 5.0	0.42+-0.02	0.27+-0.01	November 1998
230.0	3	Mars	5.0 x 5.0	0.40+-0.02	0.25+-0.01	November 1998
230.0	4	Mars	5.0 x 5.0	0.46+-0.02	0.29+-0.01	November 1998
230.0	5	Mars	5.0 x 5.0	0.49+-0.03	0.31+-0.01	November 1998
230.0	6	Mars	5.0 x 5.0	0.38+-0.03	0.24+-0.01	November 1998
230.0	7	Mars	5.0 x 5.0	0.46+-0.02	0.29+-0.01	November 1998
230.0	8	Mars	5.0 x 5.0	0.51+-0.02	0.32+-0.01	November 1998

Last modified 22 January 2000; Webmaster

12 Meter Telescope - Telescope Efficiencies

NRAO 12m Telescope Efficiencies for 2000

NRAO 12m Telescope Efficiencies for 1999

NRAO 12m Telescope Efficiencies for 1998

NRAO 12m Telescope Efficiencies for 1997

NRAO 12m Telescope Efficiencies for 1996

NRAO 12m Telescope Efficiencies for 1995

NRAO 12m Telescope Efficiencies for the 1mm Array Receiver