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Appendix 1: Station Reports

BONN CORRELATORS 1) Following 14 and a half years of service to the European VLBI community, the MPIfR Mark 2 correlator was finally switched off on 15 June 1992, and dismantled. It was becoming increasingly difficult to maintain playback recorders, essentially all Mark 2 continuum experiments are now correlated at the CIT Block 2 correlator (at the PI's wish !) and we need the space in Bonn to expand our Mark 3 correlator operation. Its remaining distinctive feature - ability to correlate Mk2 spectral line data - was only ever a pastime of a few devotees, who must now use the "sister" correlator in Socorro (until that is switched off shortly !) or move over to the MK3 or VLBA record systems. EVN historians may wish to recall that the first truly stand-alone European VLBI observations - the 18cm "JODE" experiment of January 1978 involving Effelsberg, Onsala, Dwingeloo and Jodrell - were the first astronomical observations to be correlated on the MPIfR Mark 2 correlator. One should also note that the MPIfR Mk3 correlator celebrated its 10th birthday this November ! 2) We are in the process of preparing an expansion of our Mark 3 correlator operations, in partnership with the Bonn/Frankfurt Geodesy group. This will initially involve a resurrection of our "old" Mark 3 correlator (the original 6 crates from 1982) and provision of additional playback drives to allow parallel correlating and the possibility of fringe-searching without interruption of production correlating. An HP F-series computer, for correlator control, has been acquired from the geodesy group, and the computer hardware and software is already installed. The old Mk3 correlator modules have been tested with this system and are mostly still OK. Two new Mk3 drives (with thin tape capability and VLBA-style electronics) have been ordered from Interferometrics, with the option to upgrade them to Mk4. A further drive may be ordered later. We plan eventually to convert the whole correlator centre to Mk4 operation. The MPIfR and IFAG (Frankfurt) have signed an agreement covering the first stage of this upgrade. Before the end of this year the MPIfR and IFAG will try to finalise an agreement about the joint installation and operation of an 8-station Mk4 correlator. 3) Following the successful upgrade of a new Honeywell playback drive with VLBA-style electronics (under the "First Phase" EC correlator grant), one of the older drives was removed from operation and has now also been successfully upgraded. Both of these drives, and the Penny and Giles playback drive, are now in regular use on the correlator. In summary, we have a total of 7 drives: 2 Honeywell "Mk3B" (Mk4/VLBA electronics) with a data playback quality ca. 100 times better than the 4 Honeywell "Mk3A" (not upgraded), and the Penny and Giles which approaches the playback performance of the MK3B Honeywells. Two Mk3A drives can still play back widetrack recordings although the head of one has a bad channel. One of the other MK3A drives is not currently attached to the correlator; it is awaiting a new record head and a possible upgrade. 4) In mid 1992 we suffered from a spate of broken/worn playback heads, which affected 3 correlator playback drives and the Effelsberg record terminal. These have been replaced with new Metrum (Honeywell) heads. (A replacement head from Penny and Giles could not be tested as it was found to be broken on arrival at MPI.) A new batch of heads has been ordered for replacements as others wear out. Both Effelsberg and the correlator are now back to normal operation. 5) We have started the process of copying all the old Mark 3 correlator archives (9-track "A-tapes") to DAT cassettes. We make one DAT with the original SAVEM tape format and another in the new Unix format (tar) which will also be adopted for Mk4 data. If users want to re-fringefit their old data in AIPS or with the new Unix version of the Haystack FRNGE program we will supply them with a copy of those DATs. 6) At the suggestion of Bob Greschke of VLBA correlator operations, we are setting up a European "node" for the NRAO program "TRACK" which is designed to keep track of the location and state of VLBI tapes. The Bonn node can be accessed by the EVN stations in order to register tape shipments and arrivals, etc. The Bonn copy of TRACK will communicate any changes in the tape data base regularly to Socorro, and will receive updates from the other data bases in the same way. TRACK may also become the tape data base program for the MK4 system. 7) A rudimentary version of the new Unix version of the Haystack FRNGE program ("FOURFIT") is available and running in Bonn. The input for parameters is not yet complete and it lacks an export interface. We hope to streamline the MPI "antenna-based fringe fitting" software and adapt it to the new program so that it can be installed at other institutions (quote Alef !). We now have AIPS version APRIL92 running on Sun and Convex machines in Bonn, including the recently improved FRING program for Mark 3 fringe-fitting. We plan to stay close to the NRAO development version of AIPS ("TST") by instituting a weekly "midnight job" after the OCT92 release. CALC/SOLVE is also up and running on two HP workstations. Klaus Ruf, Walter Alef, Dave Graham, Arno Mueskens, Richard Porcas EFFELSBERG 1) We have made successful test VLBI observations at 86 GHz in July, using Effelsberg, Pico Veleta and Onsala. The Effelsberg gain (K/Jy) is roughly the same as Pico Veleta at intermediate elevations ! 2) We plan a new secondary-focus receiver box containing 3 VLBI frequency bands - 15, 22 and 43 GHz. All receivers will be dual circular polarisation. Together with the present 5, 10 and 2.3/8.4 GHz secondary focus systems, this will allow future frequency-agile operation in Effelsberg and greatly facilitate VLBI scheduling. 3) Inventory of current Effelsberg receivers, specified as frequency ranges in GHz : 0.40- 0.41 / 0.61 / 1.29- 1.72 / 2.20- 2.30 / 2.60- 2.80 / 3.13- 3.35 / 4.30- 5.10 / 5.75- 6.75 / 7.95- 9.15 / 10.40-10.70 / 11.70-12.50 / 12.90-13.60 / 14.20-15.20 (soon)/ 18.50-25.50 / 26.50-36.30 / 43.00-43.50 / 86.04-86.64 , 89.04-89.64 / Dave Graham, Richard Porcas JODRELL Jodrell Station Report 25th. November 1992 The Cambridge broadband (28MHz) link hardware for remote VLBI is progressing but is not likely to be ready until Spring 1993; i.e. before the June session. The 22GHz cooled receiver is available now, TSys about 120K. The VLBA DAR software (DarFS) is now regarded as working but work will continue on it. The GSFC 'MK4 Field System' may be taken up by us in the furutre, but is presently unavailable as we are not part of the Geodesy program. The Peters Maser continues to function consistently: two Jodrell staff recently went to Tuscaloosa to learn about a modification to correct a falling IF level: this has been performed on our unit. The Jodrell VAX computers will be de-comissioned within the next month or so, and mail should now be directed to the Sun workstation network via Telnet. (vlbi@jb.man.ac.uk) Paul Burgess MEDICINA ( + Arcetri, Florence ) S/X/K receiver -------------- The most valuable work of this year was the completion of the triple band receiver mounted on the primary focus of the Medicina 32m dish. The receiver allocates concentric feeds for S/X bands and a little feed for K band, space shifted each other of about 18 cm. A mechanical movement is provided in the z and y direction for focusing and changing from S/X to K. This receiver improves many features of the our preceeding primary focus S/X.It is criogenically cooled (at about 30K),with both polarization for each band. The operation is remotally controlled (by PC software), the cooling can start while the antenna observes by secondary focus receivers so gaining time for the setup; the switching among the three bands and the complete setup for observation takes only a few minutes. Following are the specifications: 1) Receiver bandwidhts Each of the following configurations are remotally selectable a)S left/X left 2.193-2.373/8.180-8.850 GHz b) " / " "VEGA" 2.193-2.373/8.180-8.890 GHz c)X left and right 8.180-8.850 or 8.180-8.890 GHz d)s left and right 2.193-2.373 GHz e)K left and right 21.860-24.140 GHz 2) Characteristics measured on antenna Band Tsys min Max efficiency S 55 K 43% X 40 K 48% K 130 K* 35%* * preliminary results, measures in progress. To be confirmed 43 GHz receiver --------------- It has been recently tested at Medicina by the Osservatorio Astrofisico di Arcetri group. Please ask to Marco Catarzi (catarzi@arcetri.astro.it) for details on the receiver itself and to Alessandro Orfei (orfei@astbo1.bo.cnr.it) about telescope pointing problems. The receiver specifications are: Type : cooled Schottky mixer Pol. channel : single linear polarization (orizontal) Center freq. : 43 GHz Bandwidth (IF ampl.) : 700 MHz Feed : corrugated horn at the Cassagrain focus Calibration : hot load (room temperature) cold load (internal load) 1. Oscillator : 40-50 GHz Gunn diode phase locked to 100-200 MHz synthesizer 2. Oscillator : 1000-2000 MHz synthesizer (HP or R&S) MK2 Correlator -------------- The present status of the correlator is not encouraging. There were problems in communicating between the PDP11/40 and the correlator modules, then at the tape drive and finally at the floating point accelerator. It is quite hard to evaluate how many chances there are that the correlator can resuscitate. Alessandro Orfei and Franco Mantovani METSAHOVI VLBA terminal: -------------- Construction work is proceeding smoothly. The baseband converters (14) are mainly ready and waiting for final checkout. In fact we used our own BBC in the last Mk2 1.3cm session. However we had some problems with achieving the specified sideband rejection but with careful selection of the mixers and balancing both amplitudes and phases, the specifications were even exceeded. The inchworm controllers are ready and working, however there are still some problems with the VME computer. We excpect to test the terminal during the June 93 1.3cm session. Receivers: ---------- 22 GHz cooled HEMT receiver is performing well and both polarization channels are now available. Tr(left) = 61K, Tr(right) = 88 K. Work on developing a new LO is in progress. Two 43 GHz HEMT amplifiers have been purchased from NRAO and they will arrive likely before the end of this year. Design of the 43 GHz receiver will begin in the near future. AIPS: ----- Work is in progress to install the 15OCT92 version of AIPS on a 486 PC running Mach 3.0 with BSD 4.3 UNIX. We are using the FORTRAN-to-C converter "f2c" (made publicly available by AT&T) and the Gnu C compiler version 2.2.2. We have just finished "INSTEP3" and are now verifying the correctness and performance of our installation with DDT. Jouko Ritakari, Kaj Wiik, Ari Mujunen NANCAY The transit and decimetric radiotelescope at Nancay has not participated in VLBI observations for the last 4 years. A demonstration study (Phase 1) for a new focal system has been initiated by the Paris Observatory, its Meudon section and its Nancay station. It is partly funded. Its goal is to show that a sensitivity improvement of 2.5 can be achieved in the L-band. The demonstration study is supposed to last till the end of 1993. The Nancay radiotelescope is not suited for usual VLBI observations, due to its rather short contribution to the (u,v) plane coverage, and to difficulties in programming a transit telescope in a VLBI array. Nevertheless, it is thought that it could be further used for some coordinated observations with a few large antennas in Europe. In the Phase 1 study, a new design for the receiver will be proposed, and specific needs for VLBI observations might be considered. Any advice from the Network is very welcome, particularly concerning a low cost recording system consistent with at least one of the inputs of a European processor for the 1995's. Concerning the acquisition part itself, it is proposed to be consistent with the channelization of the VLBA system and its 4 BBC basic unit. Gerard Daigne NOTO 1) The 18 cm receiver is now available at the secondary focus of the telescope. Tests were planned during the last November session. Receiver specifications are quite the same as for the Medicina receiver. 2) A 327 MHz uncooled receiver was also tested at the primary focus of the telescope. Some observations were done during the November session. 3) The station is getting a new PC486 50 MHz which will be in charge for driving the VLBA terminal (still with 4 BBC's) and It will have a VENIX operating system for real time check of the VLBA terminal. The station just got a MK3 terminal from the US and it will be available for several months. The PC486 will be necessary in order to drive the VLBA recorder. Franco Mantovani ONSALA An upgrade of the surface and back structure on the 20 m telescope was made during spring. New efficiency 43% at 110 GHz. The new control system for the 20-m antenna with a HP 9000/720 is almost ready. The software is based on the PEGASUS system. A PC and the new Field System for real time UNIX (VENIX), has been purchased and will be installed early next year. A VLBA terminal and tape recorder for SEST has been purchased from Penny & Giles. Biorn Nilsson SIMEIS BEAR LAKES EVPATORIA KALAZIN USSURISSK (PUSCHINO) We have 6 cm at Bear Lakes - effective area of the antenna is around 900 m2, the noise temperature of antenna 10 K. We are making cooled receiver. Today receiver (uncooled) has temperature around 70 K. After Bear Lakes we will begin work with Evpatoria 70 m antenna, and 22 m antenna at Simeiz. We are planing 6 cm for Kalazin 64 m and Ussuriisk 70 m antennas, next year. We have today big problems with helium at Simeiz for maser preamplifier. Perhaps we shall have cooling 22 GHz preamplifier from NRAO. Effective area Simeiz 210 m2 and Evpatoria around 1500 m2. We are working for 3.6 cm cooling receiver too. Leonid Matveyenko TORUN 1. 32m dish ------------ In 1992 significant development has been done with 32 m antenna construction. All the parts up to the level of the elevation axis have been assembled and put in place. The remaining parts of antenna i.e. those of the elevation axis assembly and the dish surface panels are already supplied to the Observatory. The elevation axis assembly which is almost put together (on the ground) will be hoisted up in the beginning of 1993. The antenna control system was commissioned to new company. 2. 32m antenna equipment ------------------------ The first (out of three) installment for EFOS H-Maser was paid. The following high class equipment has been purchased for lab and receiving system needs: HP 8592B 10 kHz - 22 GHz Spectrum Analyser, HP 8720B 100 MHz - 20 GHz Network Analyser, HP 16500A Logic analysis System, HP 83712A 10 MHz - 20 GHz Synthesized CW Generator. 3. Funding ---------- Funding for the next year is provided. We expect some funding from the EC. Torun Radio Astronomy Observatory WESTERBORK ---------- 1) 4MHz filters available for all video converters (USB+LSB) to allow double-speed recording no response on test observations at double speed 2) PC field system from Effelsberg available and have made 1 test observation Problem with that schedule! (2 versions) will retry in March 93 3) intermittent problems on Mk3A a) one VC gives wrong readout freq (MAT) b) head position sensor gives wrong position while tape moving c) Decoder channel A intermittently bad 4) Current expectation date for prototype Multi-Frequency Frontend moved to end 1993. (rate of advance 1year/year) 5) Have new offline computer (HP9000 workstation). HP1000 will go in 1993, when necessary software runs on workstation (or PC). 6) Before end 1992 Westerbork will have an internet connection via Dwingeloo but speed will only be moderate ( 1kbyte/sec). Tony Foley WETTZELL I contacted Richard Kilger on 2 December by telephone, and he has agreed to provide a short station report for the meeting. The Wettzell telephone numbers changed a while back, so I give the new ones here : +49 9941 603 0 switchboard 603 263 Richard Kilger 603 262 telescope operator 603 222 TELEFAX My experience using the Wettzell e-mail address is that it is rather unstable - very often messages bounce back and don't get through. Richard Porcas pp Richard Kilger (in absentia !) YEBES Yebes has bought a VLBA acquisition terminal to Interferometrics. It will be delivered in January 1993. In December some people from Yebes will go to Interferometrics to take a training course to operate the terminal and to be able to detect and repair possible break-downs. By the end of January we will try to make a test observing session at 43 GHz to check the equipment. Our observatory is also working in the installation of an S/X receiver in the antenna. Due to the fact that the antenna is designed to be operated at mm wavelengths some modifications have been performed to allow observations at these frequencies. A new subreflector (made of carbon fiber) was designed and built. This subreflector can be exchanged with the mm one when needed. Thus, it will not be permanently installed at the telescope because it would prevent its use at mm wavelenghts. - New horns were designed and built. They will be permanently installed at the telescope. The horns were designed in such a way that when mounted will not interfere the beam at mm wavelengths. - A cooled S/X receiver is being built at our labs. By the end of the year the receiver may be completed and the antenna may be operative at these frequencies.

Pablo deVicente

jive@nfra.nl
Fri Dec 17 08:20:53 MET 1993