History of efficiencies of the 30m telescope

1) Before March 1994

Taken from IRAM Newsletter No. 5, p.2 (1 of September 1992).
The table represents a summary of measurements up to 1992.
Freq. (GHz)	Receiver	Beff	Feff	Aeff	HPBW (")	Date
43	MPI Sch.			0.57	61	07/91
85 86 90 90 90	Sch. SIS Sch. Sch.	0.65 0.60 0.54 0.67	0.90	0.53 0.47 0.53 0.58 +/- 0.03	27 26 25.3 27	06/90 88 88 86 02/92
100? 106 111 115? 115 115	SIS Sch. Sch. SIS SIS Sch.	0.57 0.56 0.59	0.89 0.89	0.45 - 0.47 0.50 0.49 0.50	22 21 21	88 88 12/91 02/92 86
140 147 150	SIS SIS	0.59 0.55	0.84 0.88	0.50	17	88 02/92 06/90
230 230 230 230 230 230 230 230.5	SIS1 Sch. Sch. SIS SIS SIS SIS	0.55 0.47 0.47 0.45	0.74 0.90 0.79 (0.90)	0.27 0.25 0.27 0.27 0.26 +/- 0.01	13.5 12.3 12.5 11.6	02/92 88 86 88 06/90 12/91 03/91
250 250 250 265 265	Bolom. Bolom. Bolom. SIS SIS	0.38 0.44 0.36 0.36	0.90	0.24 0.28 0.21	11.2 11.4 11 10.8	86 08/91 88 88 06/90
345 345 345 345 345 350 350 350	SIS Bolom. Sch. SIS MPI Bolom. MPI Sch. MPE Sch.	0.15 0.18 0.20 0.17	0.84	0.09 0.09 0.10 0.095 0.06 0.106 0.14	10 7 (?) 8.5 8.5 8.4	02/92 86 88 06/90 11/91 08/91 87

2) From March 1994 - July 1997

Taken from: The 30m Manual, v. 1.0, W. Wild, p. 65;
IRAM Newsletter No. 18, p. 2
Receiver	Freq. (GHz)	HPBW (")	Aperture Efficency Aeff	Main Bean efficiency Beff	Forward Efficiency Feff	Continuum Sensitivity (Jy / K)
3mm SIS	90 100 110	27 24 22	0.60 0.58 0.57	0.75 0.70 0.68	0.92 0.92 0.92	6.0 6.2 6.3
2mm SIS	130 150 160	18 16 15	0.47 0.43 0.41	0.58 0.52 0.50	0.90 0.90 0.90	7.5 8.2 8.6
1.3mm G1 SIS	220 230 240	10.9 10.4 10.0	0.35 0.32 0.29	0.41 0.39 0.37	0.86 0.86 0.86	9.6 10.5 11.6

3) From July 1997 - October 1999

Taken from: The 30m Manual, v. 2.0, W. Wild, p. 19;
Greve, Kramer, Wild, 1998, A&AS, 133, 271
In September 1998 new receivers (A100, A230, B100 and B230) were installed. Due to poor weather, technical problem and a large size of Mars no relyable efficiencies measurements were obtained until October 1999.
Receiver	Freq. (GHz)	HPBW (")	Aperture Efficency Aeff	Main Bean efficiency Beff	Forward Efficiency Feff	Continuum Sensitivity (Jy / K)
3mm SIS	88	27.5	0.61	0.73	0.92	5.9
2mm SIS	150	16	0.45	0.54	0.90	7.8
1.3mm G1 SIS	230	10.5	0.35	0.42	0.86	9.7

4) From October 1999 - 12th of December 2000

The efficiencies are obtained from measurement done between October 1999 and January 2000
*** The value of Feff is affected by the presence or absence of an absorbing ring around the subreflector. This absorbing ring is usually present during the time when only heterodyne observations are scheduled (in order to inhibit standing waves and improve the baseline quality) and is removed during the time when also bolometer observations are done.
Receiver	Freq. (GHz)	Main Bean efficiency Beff for B and C cryostat	Main Bean efficiency Beff for A cryostat	Forward Efficiency Feff with ring***	Forward Efficiency Feff without ring***
A100/B100	86 110	0.80 0.80	0.77 0.76	0.92 0.92	0.95 0.95
C150	145 170	0.65 0.66	- -	0.90 0.90	0.93 0.91
A230/B230	210 235	0.54 0.50	0.57 0.52	0.85 0.85	0.91 0.91
C270	260 279	0.51 0.46	- -	0.88 0.85	0.88 0.88

5) After the 12th of December 2000

The latest update of the efficiencies is valid from the 12th of December 2000 on.
At this date the forward efficiency (Feff) changed because of the installation of a new (reflecting) ring around the subreflector. This new ring does not interfere with bolometer observations and can therefore stay around the subreflector during the whole year.
The value for the main beam efficiency have also been updated, not due to significant changes with respect to the previous measurements but due to a more elaborate fit to the existing data obtained between October 1999 and November 2000.

P. Hily-Blant & U. Lisenfeld 16 May 2001