Astron. Astrophys. 361, 500-506 (2000)

2. Observations

The CO (J=10) and (21) transitions have been observed in July 1999 using the IRAM 30 m radio telescope. The beam sizes are 22" at 115 GHz and 11" at 230 GHz (corresponding to 330 pc and 165 pc at the adopted distance of NGC 3077, 3.2 Mpc). The main beam efficiencies are and , respectively. Pointing accuracy was better than 5". Spectra were obtained with a velocity resolution of 0.8 at 115 GHz and 0.4 using autocorrelator spectrometers. In total, we observed 57 individual positions simultaneously in both transitions with a wobbling secondary mirror; wobbler throw was in azimuth. The spacing between individual positions is 20" ( the size of the beam at 115 GHz).

In January 2000 we also obtained one CO spectrum in the () transition using the KOSMA 3 m radio telescope located at the Gornergrat near Zermatt in the Swiss Alps. This spectrum was obtained with a wobbling secondary mirror with a throw of in azimuthal direction. We used a medium resolution acusto-optical spectrometer with a velocity resolution which finally has been degraded to 2.3 . The main beam efficiency is , the beam size 80" (FWHM). The final rms is 4.8mK ().

© European Southern Observatory (ESO) 2000

Online publication: October 2, 2000
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