Ten years of observing with the 30-m Telescope

The first astronomical observation with the fully assembled 30 m telescope was made on 15 May 1984. From this day onwards, the telescope was used without any major shut-down and today with of the time used for observations.

In order to provide the telescope for commissioning, a number of important preparations were terminated on 15 May 1984:

• the reflector was adjusted to an accuracy of 120 microns
• the subreflector was aligned
• the Nasmyth mirrors were aligned, with M 3 following the tilt of the telescope
• the 3 mm Schottky receiver was installed, aligned and tuned to 86 GHz
• the focal plane chopper was working
• the drive program was installed and tested.
• the filter bank(s) and the continuum detector(s) were connected
• the VAX computers (A + B) were available for telescope control, data acquisition and data reduction
• the accommodation building was ready and habitable

In order to find any source, the first observation (fig. 1) was a scan across the Sun (it was cloudy), immediately followed by pointing on bright quasars. In this first observation, using the full system and with no elaborate corrections applied, we ``missed'' the point source by --- with this the telescope was considered to be ready; quickly after this the first spectra were taken (Fig. 2).

It took approximately one more year of optimization and improvements to open the telescope for guest observers (May 1985).

Many persons of the Home Institutes and of the Construction Firms participated in the final preparations.

Albert GREVE

Figure: A fac simile of the original Sun recording on May 15, 1984.

Figure: One of the first spectra taken (SiO maser in R Cas), captured on the screen of the TV monitor.