GBT Sensitivity

Appendix: GBT Gain and sensitivity.

This table lists typical system temperatures (Tsys), gains, and aperture efficiencies measured at high elevation in good weather. There is virtually no change in efficiency with elevation for frequencies of 6 GHz and lower.

Also listed are rms flux density levels for continuum observations with 80 MHz bandwidth (column 6), and various spectral line configurations (columns 7-10), calculated from the above formulas for an on-source integration time of 60 seconds.

The active surface should be used for frequencies of 8 Ghz and higher.

Col. 6: Continuum with 80 MHz bandwidth.
Col. 7: 800 MHz band, 8192 channels, 98kHz per channel.
Col. 8: 200 MHz band, 8192 channels, 24kHz per channel.
Col. 9: 50 MHz band, 9-levels, 8192 channels, 6.1kHz per channel.
Col. 10: 12.5 MHz band, 9-levels, 8192 channels, 1.5kHz per channel.

Col. 11: Confusion rms in mJy

1 2 3 4 5 6 7 8 9 10 11

Receiver FWHM Tsys Gain
(K/Jy) Ap.Eff Srms
80MHz
(mJy) Srms
98kHz
(mJy) Srms
24kHz
(mJy) Srms
6.1kHz
(mJy) Srms
1.5kHz
(mJy) Conf
(mJy)

Rcvr_342 36' 70 K 2.0 70% 0.47 12.6 25.3 42.2 84.4 920

Rcvr_450 27' 57 K 2.0 70% 0.38 10.3 20.6 34.4 68.7 432

Rcvr_600 21' 48 K 2.0 70% 0.32 8.7 17.3 28.9 57.9 200

Rcvr_800 15' 25 K 2.0 70% 0.17 4.5 9.0 15.1 30.1 91

Rcvr1_2 9' 20 K 2.0 70% 0.11 3.6 7.2 12.1 24.2 19

Rcvr2_3 5.8' 22 K 1.9 68% 0.12 4.1 8.2 13.7 27.4 6.0

Rcvr4_6 2.5' 25 K 1.87 66% 0.14 4.8 9.6 16.1 32.1 0.65

Rcvr8_10 1.4' 27 K 1.8 63% 0.16 5.4 10.9 18.2 36.3 0.13

Rcvr12_15 54" 30 K 1.7 60% 0.19 6.3 12.7 21.2 42.4 0.05

Rcvr18_22 37" 40 K 1.5 51% 0.29 10.0 19.9 33.2 66.5 0.015

Rcvr22_26 30" 40 K 1.5 51% 0.29 10.0 19.9 33.2 66.5 0.009

Rcvr40_52 16" 60 K 1.0 35% 0.63 21.7 43.5 72.7 145. 0.002

1	2	3	4	5	6	7	8	9	10	11
Receiver	FWHM	Tsys	Gain (K/Jy)	Ap.Eff	Srms 80MHz (mJy)	Srms 98kHz (mJy)	Srms 24kHz (mJy)	Srms 6.1kHz (mJy)	Srms 1.5kHz (mJy)	Conf (mJy)
Rcvr_342	36'	70 K	2.0	70%	0.47	12.6	25.3	42.2	84.4	920
Rcvr_450	27'	57 K	2.0	70%	0.38	10.3	20.6	34.4	68.7	432
Rcvr_600	21'	48 K	2.0	70%	0.32	8.7	17.3	28.9	57.9	200
Rcvr_800	15'	25 K	2.0	70%	0.17	4.5	9.0	15.1	30.1	91
Rcvr1_2	9'	20 K	2.0	70%	0.11	3.6	7.2	12.1	24.2	19
Rcvr2_3	5.8'	22 K	1.9	68%	0.12	4.1	8.2	13.7	27.4	6.0
Rcvr4_6	2.5'	25 K	1.87	66%	0.14	4.8	9.6	16.1	32.1	0.65
Rcvr8_10	1.4'	27 K	1.8	63%	0.16	5.4	10.9	18.2	36.3	0.13
Rcvr12_15	54"	30 K	1.7	60%	0.19	6.3	12.7	21.2	42.4	0.05
Rcvr18_22	37"	40 K	1.5	51%	0.29	10.0	19.9	33.2	66.5	0.015
Rcvr22_26	30"	40 K	1.5	51%	0.29	10.0	19.9	33.2	66.5	0.009
Rcvr40_52	16"	60 K	1.0	35%	0.63	21.7	43.5	72.7	145.	0.002