Abstract. We describe the technical concept, properties, and performance of HERA (HEterodyne Receiver Array) at the IRAM 30 m telescope. HERA is a multibeam, waveguide SIS receiver that greatly improves mapping speed in various observing modes and also provides possibilities for new high-sensitivity observing of small sources. Future extensions with a second polarization module will permit spectro-polarimetry. We present some examples of astronomical maps with HERA.

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The 30 m Millimeter Radiotelescope (MRT) will have a beamwidth of less than 10" when operated at a wavelength of 1.2 mm. It is an open air telescope located on a mountain ridge in southern Spain. 4here the instrument is exposed to severe environmental influences, especially wind and temperature changes. The pointing and tracking accuracy required is of the order of a few seconds of arc. Simulations have shown that these specifications cannot be met with conventional servo design. An improvement of performance can be obtained applying the modern concept of state control. The state controller needs the acquisition of data about position and velocity at several points of the instrument in real time.Additionally the state controller requires repetition rates of a few milliseconds, in which the data have to be read, converted and the servo algorithms calculated. This is performed by microprocessors operating in CAMAC crates close to the driving system. The whole system is controlled by two identical computers. One usually controls the antenna and data acquisition from the receivers, the other can be used for data analysis or as a backup controller. All receivers are connected via CAMAC, too.Special software tools have been developed for the use of this system. They allow an easy access to the variety of different process control items needed to drive the complete system. They have proved to be a powerful aid in developing the process control hardware and in the installation phase. They will be used for the communication between the operators and the system.In the development of the system the possibility of expanding the system to remote observing has been kept open. State controllerThe 30 m millimeter radio telescope (MRT) requires a pointing accuracy of a few arcseconds. Extended investigations of Juen and Zeitzl have shown that the required accuracy can only be obtained with a state controller, but not with a conventional cascade controller. Fig. 1 shows the principal structure of the state controller. It consists of a proportional feedback of position and velocity (state variables) of -antenna axis (elevation and azimuth), -motor (elevation and azimuth), -counterweight -box (azimuth), -vertical movement of the elevation bearing.The stationary position accuracy is reached by use of an integral feedback of the position error. The gains of the controller are computed by a minimizing procedure. The quantity to be minimized is the time integral over a weighted sum of the set point error and the motor torque. For this procedure a sufficiently accurate mathematical model of the telescope is essential. The weighting factors in the procedure are the design parameters of the state controller.For a satisfactory performance of the control high gains are required. High gains are obtained by choosing the weighting factor for the motor torque sufficiently small. Practical limitations for the magnitudes of the gains are:-non -linearities like friction and backlash, -time -delays in the motors, -time -delays and noise in the measu...

Astronomical observatories are today generating increasingly large volumes of data. For an efficient use of them, databases have been built following the standards proposed by the International Virtual Observatory Alliance (IVOA), providing a common protocol to query them and make them interoperable. The IRAM 30-m radio telescope, located in Sierra Nevada (Granada, Spain) is a millimeter wavelength telescope with a constantly renewed, extensive choice of instruments, and capable of covering the frequency range between 80 and 370 GHz. It is continuously producing a large amount of data thanks to the more than 200 scientific projects observed each year. The TAPAS archive at the IRAM 30-m telescope is aimed to provide public access to the headers describing the observations performed with the telescope, according to a defined data policy, making as well the technical data available to the IRAM staff members. A special emphasis has been made to IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). 66Exp Astron (2012) 34:65-88 make it Virtual Observatory (VO) compliant, and to offer a VO compliant web interface allowing to make the information available to the scientific community. TAPAS is built using the Django Python framework on top of a relational MySQL database, and is fully integrated with the telescope control system. The TAPAS data model (DM) is based on the Radio Astronomical DAta Model for Single dish radio telescopes (RADAMS), to allow for easy integration into the VO infrastructure. A metadata modeling layer is used by the data-filler to allow an implementation free from assumptions about the control system and the underlying database. TAPAS and its public web interface (http://tapas.iram.es) provides a scalable system that can evolve with new instruments and observing modes. A meta description of the DM has been introduced in TAPAS in order to both avoid undesired coupling between the code and the DM and to provide a better management of the archive. A subset of the header data stored in TAPAS will be made available at the CDS.