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News from the 30-m telescope

Answers to observers' comments

As the station manager of the Pico Veleta Observatory I am very eager to read every single comment our observers are asked to provide after their observing run. This is one of the best ways to evaluate the weaknesses and strengths of our telescope. With our engineers and astronomers we are searching for solutions to the problems pointed out, and, maybe with a delay of a couple of weeks, I answer to every single complaint. Your input is valuable - so please take the time and fill out your comment sheet.

Let me comment on some points that have bothered many of our observers earlier this year. In spring, many of our guests experienced occasional failures of the subreflector spindle control. We found some technical time to dismount the subreflector and identified the cause of our problems in a defective position encoder. Now the subreflector is tracking properly as it should.

A major source of complaints was a temporary instability of our computer system leading to frequent crashes and the infamous D-TIME error (i.e. an integration just does not stop). This behavior often occurs when there is a communication problem within the network formed by the computer, the telescope and various devices. After an analysis of the system, our computer group found a stable configuration and since then the amount of computer related problems has decreased significantly. This shows the necessity to replace our antenna control and data acquisition system (about our efforts, see our web page at

I received very enthusiastic comments about our new generation receiver system (A100, B100, A230, B230). The B receivers were replaced this spring and have an even better performance now over their tunable range. Unfortunately our old, and up to now faithful, 2 mm receiver gave problems: the receiver temperature was slightly higher than normal, and it was not always easily tuned. But in September it will be replaced by two new generation 2 mm receivers (C150 and D150). In addition, we will get two receivers for the upper 1 mm window (C270 and D270), which will strengthen the position of the IRAM 30-m telescope as the best telescope for the mm-range.

Rainer Mauersberger, Station Manager

Time estimator, Version 2

The Time Estimator (TE) in its first version has been heavily used to prepare the proposals for the summer'99 period (see Newsletter of January 99). More than half of the observers used it to estimate their observing time. From the reading of the proposals and some suggestions we collected along the last months, the tool has been updated to version 2 and should be closer to user expectations.

The new release, available on the IRAM Grenoble and Granada web pages, now includes continuum observations with bolometer arrays, in both ON/OFF and mapping modes. It still contains all available spectroscopic observing modes with some new features (e.g. average of receivers observing at the same frequency). For a detailed description of the updates, refer to the help page on the web. A more complete information about the program can also be found in a recent report [1].

Version 2 accounts for the most recent receiver parameters, notably the improved performances of receivers B100 and B230, and for the 4 new receivers in dewars C and D. Their parameters, which are currently based on lab measurements, may be updated as soon as measurements on the telescope are available. Please send your comments on the current version 2 of the tool to the undersigned.

David Teyssier
$\;$[1] A Time Estimator for Observations at the IRAM 30-m Telescope, David Teyssier. Available on IRAM web pages.


David Teyssier will leave the Pico Veleta Observatory this September and start to write a Ph.D. Thesis at the Ecole Normale Superieur in Paris. His new email address will be . David has served as a cooperant, in France an option to the military service, for two years. During that period he has not only assisted many of our guests in doing their observations, he was also very involved in developing our spectral line On-The-Fly Mapping procedures. He wrote our web based observing time estimator and investigated the influence of thermal gradients in the 30-m antenna on the surface accuracy. We wish him all the best for his future career as an astronomer.

Our regular observers know that winter transport to the telescope can often be difficult given the uncertainties of road and weather conditions. Our guests are therefore invited to plan the length of their stay generously. But if we have to cancel a transport, be advised that our remote observing station in Granada can be used.

Finally, I invite you to check our web pages, which not only have a new design but also contain new information. In particular, a Meteosat movie of the precipitable water vapour (PWV) is now available to help you to plan your observations (

Rainer Mauersberger

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