Reminders

A handbook (``The 30m Manual'') collects much of the information necessary to plan 30m telescope observations[6]. It is however outdated in many sections, and we recommend also to consult the NCS web pages (../IRAMES/ncs30m) The report entitled ``Calibration of spectral line data at the IRAM 30m telescope'' explains in detail the applied calibration procedure. Both documents can be retrieved from the URL http://www.iram.es/IRAMES/otherDocuments/manuals/index.html. A catalog of well calibrated spectra for a range of sources and transitions (Mauersberger et al. [9]) is very useful for monitoring spectral line calibration. A copy of the 30m file with the calibrated spectra can be downloaded from the Spanish web site. The astronomer on duty (whose schedule can be found at URL ../IRAMES/groups/astronomy/aodsched.html) should be contacted well in advance for any special questions concerning the preparation of an observing run (e.g. setup of on-the-fly maps etc). Frequency switching is available for both HERA and the single pixel SIS receivers. This observing mode is interesting for observations of narrow lines where flat baselines are not essential, although the spectral baselines with HERA are among the best known in frequency switching. Certain limitations exist with respect to maximum frequency throw ($\le 45$ km/s), backends, phase times etc.; for a detailed report see [4]. This report also explains how to identify mesospheric lines which may easily be confused in some cases with genuine astronomical lines from cold clouds.