Table 2: Absolute surface brightnesses (in Jy/beam) of Mars, Uranus, W3 OH, K3-50A and NGC 7027 adopted for the computation of the Kelvin-to-Janksy conversion factors of the 30 m telescope at 86 GHz and 229 GHz.

	UT days of Nov. 2003
Source	11	12	13	14	15	16
86 GHz
Marsa	149.75	146.88	144.08	141.33	138.65	136.02
Uranusa	7.06	7.05	7.04	7.03	7.01	7.01
W3 OHb	3.94
K3-50Ab	6.29
NGC 7027b	4.71
229 GHz
Marsa	691.16	683.33	675.51	666.71	659.92	652.17
Uranusa	32.88	32.83	32.77	32.72	32.67	32.61
W3 OHb	6.48
K3-50Ab	6.98
NGC 7027b	3.68

a Computed from the expressions given in Kramer (1997), and references therein, which take into account the angular size of the planets. The values given for Uranus were computed from an empirical model which used Mars as primary calibrator (Griffin & Orton 1993). b Obtained from averages of measurements performed during several years - before 1996 - at the IRAM 30 m telescope. These measurements were themselves calibrated through observations of planets. The sizes of these calibrators at 1.2 mm are given in Lisenfeld et al. (2000).