EVN Technical & Operations Group (TOG) Meeting Monday 4th December 2006 Noto, Italy Introduction ------------ The EVN TOG held a meeting on 4th December 2006 at the Noto radio telescope, Italy. 27 people attended the meeting. The chairman was Alef. Cassaro welcomed the participants and outlined local arrangements. All reports and presentations from the meeting are available on the web at http://www.mpifr-bonn.mpg.de/div/vlbicor/tog_chair/togreps06-2 1. Approval & last minute additions to Agenda --------------------------------------------- The agenda was approved, with an additional 10 minutes allocated for Ritakari to present e-VLBI developments at Metsähovi. 2. Review of Action Items from last meeting ------------------------------------------- The TOG reviewed action items from the previous meeting. 1. Action: Garrington to make the Mk2/Lovell phase referencing technique available as a working process for users - ongoing. This has been tested and some progress made, but option is not yet readily available to users. 2. Action: All stations should look at data regularly with chchk program, use it to locate significant RFI and report the results to Polatidis and CRAF representatives, and use it to check phase-cal throughout the session - continuing. Polatidis mentioned that some reports had been recently received and would soon be included in the Status table. Mantovani noted that the CRAF chairman had complained about not receiving enough information on RFI. Alef urged all stations to please take RFI reporting seriously as this information is important for CRAF. Some concerns were raised about the sensitivity of the RFI monitoring receivers which are installed at some stations. Action Item: Polatidis, Lindqvist and Burgess to define standards for RFI monitoring and report at the next meeting. 3. Action: All stations should look at pipeline results available from the JIVE webpage, in particular amplitude corrections found by selfcal on strong, compact calibrators - continuing. Stations reported that pipeline results are useful. 4. Action: All stations to provide detailed Wx and RFI comments in experiment logs - continuing. In general this seems satisfactory. 5. Action: All stations to continue monitoring Tcal throughout sessions - continuing. This has been OK except there is a problem for Cambridge (to be discussed later). 6. Action: de Vicente to report on implementation of continuous tpi on VLBA systems - de Vicente could not attend the meeting due to cancelled flights, so the action remains open. Graham reported that some progress has been made. 7. Action: Stations to produce ANTAB and RXG files as soon as possible after the end of a session - permanent action. Alef to request feedback from users as to whether they would prefer calibration data in two stages (first quick preliminary and then final numbers later) or whether they would prefer to wait longer and have high quality calibration data to start with - feedback to be presented at the EVN users meeting in Torun. Evidently users do not want the two-stage calibration option. The deadline for submission of ANTAB and RXG files is 2 weeks after the end of a session. It is desirable to send files sooner if possible. Directors were asked to give calibration file production a higher priority and allow Friends more time for this if needed. 8. Action: All stations to forward FS error log files to Himwich and include details of what the FS was doing when the crash occurred - ongoing action. No FS crashes were reported since the last meeting. 9. Action: Reynolds and Walker to incorporate frequency agility information in SCHED - stations will be prompted to provide this information. Polatidis then to update the EVN status table with new/additional frequency agility information - action remains open (Reynolds absent). Campbell reported that frequency agility information is expected to be included in the Spring 2007 release of SCHED. 10. Action: All stations to look at NME reports sent by JIVE - ongoing. Stations regularly look at NME reports. 11. Action: Whitney to find out whether a spare extender cable is available at Haystack to loan to Torun for testing BBC problems - Smythe reported that this was done. 12. Action: Alef to send information regarding monitoring of scan_check during recording - how to check for discrepancies in scan values and flag problems in the display window - there was uncertainty over what specifically this action meant. Smythe to explain scan_check in his presentation. 13. Action: Himwich, Graham and Gunn to include Graham's monitoring software with future distributions of the Field System - Himwich to discuss the available FS monitoring and display options in his presentation. 14. Action: Gunn to send email before each session when the final versions of all schedules are ready for download - ongoing. This has been satisfactory. Campbell usually prompts Gunn to send the email. 15. Action: Reynolds to request feedback re. amplitude calibration from spectral line users at JIVE in order to assess results of different calibration methods - status unknown at meeting, but subsequently Reynolds reported that feedback from spectral line users has been received. A lot of spectral line observations also need good quality a priori Tsys. 16. Action: All to check that Mk5 modules are placed squarely on a flat surface when received, otherwise connectors are easily damaged when bent 8-packs get inserted in Mark 5 units - ongoing. Campbell mentioned that one or two damaged modules have been received at JIVE. Alef reiterated that it should be standard procedure to avoid backplane damage, as replacement is very expensive. Currently there are no spare backplanes available - later discussion 17. Action: All stations to try to run the FS diagnostic tests and investigate the results - ongoing. Lindqvist reported that the tests had been done at Onsala and worked well. He recommended that others try the tests. 18. Action: Reynolds to look into scheduling of Lovell+MkII for phase-referencing - done, see following item. 19. Action: Paragi to arrange a test of the Jodrell MkII/Lovell phase-referencing technique for a C-band NME - done in N06C5. 20. Action: Reynolds to work with Rene Vermeulen on the guide for polarization calibration using WSRT local interferometry data - ongoing. Foley reported that Westerbork regularly monitors calibration sources locally. A user guide is still needed. 21. Action: Gunn to present an inventory and status report on Mk5/disk spare parts at the next TOG meeting - Burgess maintains all information on the Jodrell web site (see http://newton.jb.man.ac.uk/Mark5A/sparemk5.htm ). Burgess requested that all updates be emailed to him. 22. Action: Alef to establish contact with Brian Corey regarding DBBCs - closed. A DBBC test will be done between Noto and Westford. 23. Action: JIVE support scientists to give detailed feedback to Shanghai regarding problems with the K-band data from session 3/2005 - Bignall discussed plots with An Tao who had some ideas about possible causes of K-band problems at Shanghai. As yet there have been no subsequent K-band observations scheduled. 24. Action: Paragi to implement labelling of fringe plots with sky frequency and sideband - still to be done 25. Action: Orlati to ask the vlbeer maintainer (Mauro Nanni) to create a subdirectory called e.g. 'latest' or 'checked' for stations to download schedules from. Alef, Campbell, Foley and Gunn to distribute an email to all stations detailing the new procedure - done 26. Action: Reynolds to fix the problems with ANTABFS for VLBA racks - done 27. Action: Graham, Lindqvist to form a small group to discuss via email opacity corrections at high frequencies, and prepare a document to present at the next TOG meeting - presentation by Graham 28. Action: Alef to contact Phil Diamond regarding calibration of Cambridge data - done, but there are still some problems 29. Action: Graham, Himwich and Lindqvist to solve problem with flux estimates for primary calibrators (Cas A etc.) in FS - done 30. Action: Alef to include on TOG webpage the collection of URLs where stations can look for experiment feedback - done. JIVE webmaster (Lisa Harvey-Smith) to add this also to 'VLBI links' on EVN web site - still to be done 31. Action: Campbell to write a summary of data products available from JIVE - done 32. Action: All stations should condition disk packs if time permits, especially those which are to be used for 1Gbps recording - continuing. This is being done on a best-effort basis. There was some discussion of disk conditioning procedures. Smythe recommended all to look at the report of conditioning and the status display in order to identify slow disk drives. Any slow disks should then be assigned to low data rate experiments. Use the stickers on the modules for reporting slow disks, as these will reduce the available bit rate. Burgess noted that Jodrell tries to replace any slow disks with spares. The main priority is not to lose any user data. When the capacity of a disk pack changes, the VSN should be retired and a new one started. Alef keeps track of changes in the disk inventory. 33. Action: All stations which do both astronomy and geodesy should clearly distinguish between astronomical and geodetic 8-packs and ensure there is no "leakage" into the wrong pool - ongoing. Leakage has not been a big problem, although Alef noted that ~10 TB of disk-space is unaccounted for. It is recommended that geodetic stations use different numbering systems to easily distinguish between astronomical and geodetic 8-packs. If any geodetic packs are found at JIVE, these should be sent to Effelsberg for return to the geodetic pool. Action Item: Alef to distribute astronomical/geodetic disk database information to Haystack. 34. Action: All stations to ship disk packs as soon as they are full - ongoing. According to the 'Bologna Rules', recorded disks should be shipped at least once a week. 35. Action: Disk packs should be shipped with one European and one US address on covers so they can be easily returned in case a shipment is lost - ongoing. Some clarification of this item was needed - this does not include any disk pack labelling, simply requires attaching addresses to the metal cover "If lost in transit, send to
in the US or
in Europe". 36. Action: Foley to start a wiki page for FS documentation, which all users can contribute to - remains to be done. 37. Action: Himwich to send message to EVNtech regarding the location of the FS "toolbox" package to install - done. 38. Action: Whitney to check the status of the problem with recording stopping, or Mk5 not responding for a period of time, when the key is turned (for changing a module while the other is recording) - Smythe reported that this has been fixed. 39. Action: All to send e-mail to Alef within 4 weeks (i.e. by 21 April) regarding the feasibility of attending a TOG meeting at Arecibo. Include any conditions, such as financial support needed - Alef thanked participants for their positive responses, however the TOG meeting in Arecibo was not approved by the CBD. Burgess noted that due to spam problems, the EVNtech distribution list has been rebuilt, and everyone needs to resubscribe if they haven't already. Ritakari suggested that an archive of EVNtech mail would be useful. Others agreed. Action Item: Burgess to look into making the EVNtech mail archive accessible on the web. 3. Reliability/Performance of the EVN ------------------------------------- Campbell reported on Network reliability (on behalf of Reynolds; see presentation online) Campbell noted the recent change of roles at JIVE. Paragi has a new e-VLBI postdoc position at JIVE and is no longer responsible for the NMEs. Stations should contact Campbell and Reynolds regarding NMEs. The changed schedule download procedure introduced in session 2/2006 seems to have worked fine. "Near-realtime" fringe checks have been successful in catching problems. The UHF experiments in session 2/2006 suffered from severe RFI. As the observations were outside protected bands, it may not be useful to report these to CRAF. However Smythe commented that low frequency RFI problems can sometimes be solved and cited some examples at Haystack of fixes, implemented by cooperative neighbours, to stop RFI due to electronic equipment. Some data in session 2/2006 were lost due to intermittent communication problems between the FS and Mk5 unit - Smythe to comment on this later. Outside the session, there were many problems during the e-VLBI ad-hoc experiment to observe RS-Oph. There was some discussion of faulty disk replacement. Sometimes faulty disks sent back to stations have not been clearly marked as broken, so better communication (labelling and email) is needed when faulty disks are returned to stations. Smythe noted that for some disk brands (e.g. Hitachi, Maxtor, possibly Seagate) it is very easy to obtain replacements online under warranty from anywhere. A return merchandise authorization (RMA) can be obtained from the manufacturer's web site. By entering the serial number, information is provided on the warranty status and whether the disk can be returned. Schonewille reported that JIVE had recently obtained 5 new disks this way. The introduction of disks has significantly improved the EVN Reliability Indicator (ERI, fraction of "good" visibilities out of expected visibilities) by roughly 15%. Also the processing factor, defined as the ratio of correlation time to observing time, has significantly improved. For non-Gbps experiments the processing factor is <1.5, however for Gbps the processing factor is larger. The main limitation is the station units, so this is expected to improve with the introduction of Mk5B. Initially following the introduction of Gbps recording there were some problems with video cable interference, but these have subsequently been avoided. Correlation of more than two MERLIN antennas has been demonstrated successfully. Cambridge and Darnhall were recorded on one pack and data were copied to another pack at JIVE. This worked OK, only some editing of the vex file was needed. This could be made a standard procedure for users. Burgess estimated that the option would be viable for two years, as the bandwidth to MERLIN outstations is unlikely to be upgraded for at least a year. After discussion it was decided that this could be done as the default for joint EVN+MERLIN observations. Users then should not need to specifically request the extra MERLIN antenna to be correlated at JIVE, however they should know in advance what data they will get. In special cases it may not be desirable to correlate an extra MERLIN antenna (e.g. if spectral resolution is compromised). The CALC model has been upgraded. It can now make use of atmospheric pressure information in calculating tropospheric delay. Thus recorded weather information is now important. Action Item: (Non-geodetic) Stations to check weather log in FS, as atmospheric pressure information can now be used. Updates every 5--10 minutes should be adequate for corrections. Campbell summarised data products available at JIVE: NME reports, Standard plots made before FITS files are produced which show small subsets of the data, and pipeline products. Currently everything is linked by experiment. It would be useful to also have links to data products by station. Some thought would need to go into how to set this up. There was some discussion of effective feedback to stations. It is important to email individual stations if a previously unknown problem is found. Also it would be useful for JIVE support scientists to include mapping of subband to BBC in the PI cover letter, which stations can also view on the archive. There was a complaint about some pipeline gain calibration data not being accessible on the archive. In general these should be public, so JIVE support scientists should check that the password protection is set correctly (for proprietory data only) after archiving the pipeline products. Charlot reported on phase-cal investigations with geodetic data (see presentation online). He showed plots of amplitude versus phase of phase-cal tones. Phase-cal amplitude should be constant with phase, however a problem was found with Urumqi phase-cals. More recently a new X-band receiver has been installed at Urumqi, so the problem may not be there any more. JIVE can now extract two phase-cal tones so in principle could produce similar plots for experiments with phase-cal on. Stations can also plot all their own phase-cal tones with the decoder. Himwich is to add an amplitude versus phase plot feature. It was noted that inspection of phase-cals is a useful diagnostic for many things, not only receivers. Action Item: Campbell to look into producing phase-cal plots at JIVE. Polatidis noted that more information on RFI is needed from stations. Updated information for two stations has just been received and will appear in the status table soon. RFI feedback from JIVE (and WSRT plots from Foley) can also be sent to Polatidis and CRAF, especially from spectral line experiments. Alef reported on feedback from the questionnaire. Stations perform various checks before the session. A good approach is to treat each session as a project, and plan several weeks in advance for what needs to be done. It is useful to produce an easily readable plan of the block schedule at each station. Some stations use a web-based system for planning and checks. Jodrell was still to send their feedback to Alef, however Burgess noted that Gunn has produced a web display for use at Jodrell - anyone interested in using such a display can contact Burgess. One important pre-session check is to route all 64 tracks through the decoder in order to check all connections etc. It is also important to establish tight communications so that operators know if anything in the system has been changed, and can quickly telephone in case of problems. It is recommended that Friends monitor experiments remotely (tail log files etc.) whenever possible. PC and FS clock checking is crucial. An operator checklist is very useful. During the session, the 'greplog ' command in the FS is useful to inspect errors logged. The snap command 'lastcheck' is also handy for a quick look at the last scan_check or data_check. Regular monitoring of scan_check is important. It is also important to monitor BBC levels and lock status. Foley noted that at Westerbork, they have set up for some error messages to ring the control room phone to alert the operator. There was some discussion of the use of VNC for monitoring operations remotely. Burgess said he would post some notes on how to use VNC through ssh. There was some further discussion of checking IF levels by sampler statistics, using the systest procedure library. Alef emphasised that it is important for all stations to measure sampler statistics every session. Action Item: JIVE support scientists to include checking of sampler statistics as part of NME feedback. 4. Amplitude Calibration ------------------------ Campbell reported on amplitude calibration (on behalf of Reynolds; see presentation online). Generally the timely availability of amplitude calibration data has improved, although the two-week deadline is not always being met. The latest ANTABFS software version is 3.4 (Effelsberg use their own software). The calibration of e-VLBI data needs to be addressed. A calibration scheme is being worked on at JIVE. There was some discussion of the problem found with N06M2 pipeline results - as outlined in Graham's presentation (available online), gain corrections derived from amplitude self-calibration were inaccurate because of complex source structure in the source selected as the calibrator. The automatic pipeline did not work well in this case. When the "target" source was selected for self-calibration in the pipeline, amplitude gains were more constant and closer to 1 as the source structure was much simpler in this case. The archive could be updated with pipeline results after swapping the target and calibrator in this case. Stations cannot be expected to assess the effects of source structure in inspecting amplitude gain statistics from the pipeline, so this needs to be addressed at JIVE. Possibly closure quantities could be used to assign a quality flag to a source. Charlot commented that problems could be avoided with careful source selection. Action Item: JIVE support scientists to look into a scheme to estimate the quality of pipeline amplitude calibration results. Graham also raised some concerns about the gain corrections derived by the AIPS pipeline. His investigations suggested more accurate results could be obtained with Difmap using 'gscale' after phase self calibration. No major problems from calibration runs were reported by stations. A minor feature still to be implemented in GNPLT is separate receiver temperatures for LCP and RCP. Graham reported on 22 GHz calibration, in particular the issue of whether gain curves include opacity corrections or not. Alef said that a uniform approach at all frequencies would be preferable. He suggested that all gain curves be free of correction for opacity. This approach of effectively taking the telescopes outside the atmosphere is used at the VLBA. Graham has checked that GNPLT produces gain curves free of opacity in the correct way. PIs are then recommended to apply opacity corrections using APCAL in AIPS (important for frequencies above 10 GHz). Spectral line measurements can be calibrated using autocorrelation spectra in which case it is not a problem if PIs do not apply the opacity corrections with APCAL. Action Item: Friends to provide gain curves free of opacity corrections (as if taken outside atmosphere). Campbell to inform users. Also PIs of 22 GHz experiments to be informed that Onsala has a different method of calibration at 22 GHz (hot load instead of noise diode), which means that Tsys values are already corrected for opacity. Graham's presentation included the status of continuous 80Hz calibration for VLBA terminals. The code is currently in a local version of FS 9.7.7. Some recoding is needed to incorporate it in a more modular structure. Graham presented a plot of Tcal versus frequency for 80Hz switched cal, showing that 80Hz reported a 5% lower Tcal than on/off method, probably because of blanking and risetime effects. Burgess was asked to report on the status of Cambridge calibration. Some progress has been made on the hardware. Currently, implementation is mainly limited by manpower, but some tests may be possible for the next session. From stations represented at the present meeting, it was felt there was no need for a calibration "tiger team" at present. Use of Westerbork and Effelsberg flux measurements was discussed. Foley asked where is an appropriate place to put the WSRT flux density measurements. The availability of these data should be emphasised to PIs. Effelsberg also regularly measures standard calibrator fluxes. (PIs still need to make a special request if they want single dish flux measurements for their program sources.) Action Item: Campbell to determine an appropriate place to put WSRT and Effelsberg calibrator flux measurements. Foley reported on Westerbork status. As the tied array is not controlled through the Field System, some work was needed to implement off-source flagging. For the flag file it was was decided to define "on-source" as when a majority of the antennas in the tied array are on source. This is now implemented, with 10s granulation. Comment strings are written to the log file when (1) most antennas are on source, and (2) when all antennas are on source. 5. Mark 5 --------- Smythe reported on the status of Mark 5A/B/B+. Mark 5B features full VSI-H compatibility. The system is now in regular use at Westford. The difference between Mark 5B and B+ is the Amazon StreamStor board, allowing a maximum data rate of 2Gbps. Action Item: Smythe to send email reminding stations of procedures for checking recording. Briefly, important checks include: scan_check for missing or extra bytes which could indicate cable interference, in which case it is recommended to look at errors on the decoder and check that cables are not near metal objects; tail -F ; checking sampler levels. Smythe noted that Burgess has a clearly written summary of the diagnosis and repair of the data "throttling" problem found at Jodrell, which turned out to be due to a faulty chip in the clock module. Mantovani mentioned that some stations are entitled to a free upgrade from Mark 5A to B. Alef gave a brief summary of EVN Mark 5 status. Smythe gave a presentation on Mark 5 software status. In the Conduant SDK 7.5 release, the problem of recording stopping when the key switch is turned has been fixed. Szomoru commented that possible unresolved issues for the correlator need to be investigated before upgrading Mark 5 software. Action Item: Smythe will contact Brisken to organise a teleconference with NRAO on Mark 5 software status. Smythe summarised development of application software to control the Data Input Module ("dimono") and Data Output Module ("domino") capability. Mark 5B DOM support is correlator specific. Smythe also summarised Mark 5 OS Software status. Linux Redhat 9 is no longer supported, Debian "Sarge" Linux is the new standard OS, with plans to support Debian "etch". Chet Ruszczyk plans to distribute the OS update as a standard ISO image. Points were made that it is critical that the Conduant software and Jungo driver work with the new Linux distribution. Any problems must be sorted out for Mark 5B. Graham is to keep EVNtech informed about solutions to current problems. Alef presented the Disk Inventory status. Updates were still needed from a number of stations. 835 TB were accounted for in the EVN pool, out of 1038 TB purchased in total. The numbers are approximate as some stations do mm and geodetic observing. Still, approximately 160 TB of disk space was unaccounted for. This is a considerable amount as 100 TB costs EUR 35k. Disk availability is sometimes an issue. It should be possible with current resources to schedule 400 TB in a session - if not then we should find out what the problem is. Campbell reported on the status of disk throughput at JIVE. The EVN aims to recycle disks within 2 sessions (for comparison the VLBA has a <30 day turnaround). Campbell encouraged all stations to keep informing JIVE of preferred shipping companies and to communicate prices of shipping in order that the costs of shipping to different stations can be compared. Alef reported that the Scheduler aims to make 1 Gbps recording the default for continuum experiments in 2007, although it is preferred to "ramp up" to this rate rather than make a sudden step. Mark 5 logistics were discussed. It was decided that if possible, a faulty disk should be sent directly to the manufacturer for replacement, from wherever it is found. If the warranty does not allow for this, then the faulty disk must be sent back to its station. If a faulty disk is sent back from JIVE to a station, then JIVE replaces the disk with a new one. Schonewille reminded stations to which faulty disks are returned to please send replacement disks to JIVE. Lindqvist enquired about the disposal of tapes. In general tapes can be discarded, except approval is needed to do anything with those from JPL/DSN which are US government property. Action Item: Alef to send email to stations regarding disposal of tapes. At the last TOG meeting is was agreed to try plastic envelopes for disk labels similar to NRAO, but these turned out to be difficult to find. Most people are happy to keep using luggage-tag labels. 6. Field System, status and new features ---------------------------------------- Himwich reported on Field System status. The current release is 9.9.2, with 9.9.3 expected in Winter 2007. In the current FS, automated (schedule-initiated) FTP has been implemented based on the approach used by Burgess. It is controlled from the 'Data Transfer Override' menu, and uses a locally customized autoftp script which transfers data using ssh (RSA key-pair exchange). 7. SCHED Developments --------------------- Campbell reported on SCHED developments (on behalf of Reynolds). Stations are urged to check that catalogs are up-to-date. Implementation of frequency agility information in SCHED is possible, but it is currently not entirely clear how useful this would be for the EVN in practice. There was a brief discussion of how to phase in AutoFTP for user experiments, e.g. if these should be inserted into fringe-finder scans at JIVE (which would require SCHED key files to be re-processed at JIVE) or if PIs should be advised to include ftp scans themselves. Alef suggested it would be good as an extra check to do periodic ftp fringe tests throughout the session. 8. Sessions ----------- Some users require more frequent observing. Friends were asked about the feasibility of doing more frequent, shorter sessions (e.g. 4, 5, or 6 sessions per year of about 1 week). The conclusion was that in principle this would be possible for stations, but would be more work, as most of the work goes into setting up for a session. There was some concern expressed that more frequent, shorter sessions would decrease reliability. 9. Digital BBCs --------------- Tuccari gave a presentation on the status of the EVN DBBC project. The most commonly used bandwidth configurations are implemented in DBBC v.1.1. For DBBC v.2.0, a faster AD sampler and FiLa10G board are being developed in collaboration with Michael Wunderlich at MPI. An RFI mitigation board is also under development. DBBC technology is also being used in the development of an L-band digital receiver at Effelsberg and Noto. A reduced version of the DBBC was used (with PC-EVN recording) in recent fringe tests with Evpatoria (Ukraine) and Irbene (Latvia) in August and November 2006, respectively. With minimal architecture the DBBC costs EUR 6k. For a complete system the cost is from EUR 30k up to 65k depending on configuration. Ritakari briefly discussed the possible use of two 10Gbit/s Ethernets in DBE boards (as referred to in his email to EVNtech of 15 November). Smythe reported on DBE development at Haystack (see presentation online). A test of the DBE prototype, using it simultaneously with Mark 4, produced excellent agreement between fringes from the two different backends. The polyphase filterbank is cheaper than Tuccari's DBBC but not as flexible. Development over the next 2.5 years is being driven principally by the VLBI2010 vision which aims at flexible observing between 100 MHz and 15 GHz. 10. Spare parts --------------- Burgess reported on Mark 5 spares and support. A list is maintained on the web site http://newton.jb.man.ac.uk Updates to spare parts and documentation of fixes should be emailed to Burgess. There was some discussion over whether it would be useful to purchase spare backplanes. Funds would be required for this. Action Item: Alef to ask Mantovani if Directors can donate money to purchase spare Mark 5 backplanes. Smythe noted that it is important to check the screws connecting the voltage supply to the backplane as these connections are a potential source of problems. 11. e-VLBI status ----------------- Szomoru reported on e-EVN developments (see presentation online). A new Network Engineer for EXPReS has just started at JIVE; there was some delay in filling this position. Many new (web-based) monitoring tools and web-based post-processing are under development. Options for adapative scheduling are being investigated; there are a number of issues to consider. Szomoru summarised connectivity status of EVN stations and improvements being made in various data transfer protocols. He also noted that lightpaths across Europe are currently available and affordable. The final date for delivery of EXPReS is in 3 years' time, however most deliverables in the Document of Work are due in 2 years. Smythe reported on e-VLBI projects underway at MIT Haystack (see presentation online). Automated e-transfers are being done, where data are transferred from Japanese stations in K5 format, then converted to Mk5 format, written to disk and correlated. E-transfers from more stations are planned soon. VSI-E testing is ongoing. e-VLBI tests with Pie Town are scheduled for 2007. Ritakari reported on e-VLBI developments at Metsähovi (see presentation online). He discussed use of a realtime version of the tsunami protocol with a fast server for large-bandwidth real-time data transfer. He also discussed the possible use of Playstation 3s as processors for software correlation. Some of the new iBob technology will be used in the Mileura recombination experiment, planned to be installed in 3 months' time. 12. Station & correlator reports -------------------------------- Foley reported on Westerbork VLBI operations (the presentation is available online). Westerbork operations have dropped in ASTRON's priority to favour LOFAR developments. The Digital Tied Array (TADU) is designed to interface directly to a Mark 5B. A design flaw was found in the digital filtering which has delayed the project. However, TADU is expected to be working some time in Spring 2007, at which time tests with other stations will be requested. Other station reports were not presented orally but are available to read on the web. It was noted that urgent maintenaince is required at Medicina (a drive) and Noto (azimuth rail). Directors should do all in their power to ensure the continued reliable operations of these vital EVN stations. It was also noted that the new subreflector at Effelsberg is now in place. 13. AOB ------- None. 14. Wiki for the TOG? --------------------- A TOG wiki page was started on the RadioNet (MoinMoin) wiki but this has not been used much so far and was not felt to be an appropriate place for technical documentation. 15. Time and Place of Next Meeting ---------------------------------- Alef suggested that two TOG meetings in the next year would be useful to evaluate the phase-in of Mark 5B and DBBCs. It was decided that the next TOG meeting would probably be held in early May, possibly in Bonn or possibly even combined with the TOW in Haystack (30 April - 3 May). The meeting should preferably be at least 4 weeks before session starts on 31 May. This would also be close to the time of DBBC and EXPReS CDRs, and the Global mm session on 10-15 May. It is anticipated that the TOG will have another meeting combined with the CBD meeting in Yebes (12-14 November), in which case it may be desirable for the session to finish earlier than 8 November. Alef will consult with the scheduler on this matter. Action Item: All to send constraints for the next TOG meeting to Alef. 16. Summary of action items --------------------------- Action Item 01: Garrington to make the Mk2/Lovell phase referencing technique available as a working process for users. Action Item 02: All stations should look at data regularly with chchk program, use it to locate significant RFI and report the results to Polatidis and CRAF representatives, and use it to check phase-cal throughout the session. Action Item 03: Polatidis, Lindqvist and Burgess to define standards for RFI monitoring and report at the next meeting. Action Item 04: All stations should look at pipeline results available from the JIVE webpage, in particular amplitude corrections found by selfcal on strong, compact calibrators. Action Item 05: All stations to provide detailed Wx and RFI comments in experiment logs. Action Item 06: All stations to continue monitoring Tcal throughout sessions. Action Item 07: de Vicente to report on implementation of continuous tpi on VLBA systems. Action Item 08: Stations to produce ANTAB and RXG files as soon as possible after the end of a session, within 2 weeks. Action Item 09: All stations to forward FS error log files to Himwich and include details of what the FS was doing when the crash occurred. Action Item 10: Reynolds and Walker to incorporate frequency agility information in SCHED. Action Item 11: All stations to look at NME reports sent by JIVE. Action Item 12: Gunn to send email before each session when the final versions of all schedules are ready for download. Action Item 13: Reynolds to report on the feedback re. amplitude calibration methods from spectral line users at JIVE. Action Item 14: All to check that Mk5 modules are placed squarely on a flat surface when received, otherwise connectors are easily damaged when bent 8-packs get inserted in Mark 5 units. Action Item 15: All stations to try to run the FS diagnostic tests and investigate the results. Action Item 16: Reynolds to work with Rene Vermeulen on the guide for polarization calibration using WSRT local interferometry data. Action Item 17: Paragi to implement labelling of fringe plots with sky frequency and sideband. Action Item 18: JIVE webmaster to add URLs where stations can look for experiment feedback to 'VLBI links' on EVN web site (see TOG webpage) Action Item 19: All stations should condition disk packs if time permits, especially those which are to be used for 1Gbps recording. Action Item 20: All stations which do both astronomy and geodesy should clearly distinguish between astronomical and geodetic 8-packs and ensure there is no "leakage" into the wrong pool. Action Item 21: Alef to distribute astronomical/geodetic disk database information to Haystack. Action Item 22: All stations to ship disk packs as soon as they are full, at least once per week. Action Item 23: Disk packs should be shipped with one European and one US address on covers so they can be easily returned in case a shipment is lost in transit. Action Item 24: Foley to start a wiki page for FS documentation, which all users can contribute to. Action Item 25: Burgess to look into making the EVNtech mail archive accessible on the web. Action Item 26: All (especially non-geodetic) stations to check FS weather logging, as the information can now be used. Action Item 27: Campbell to look into producing phase-cal plots at JIVE. Action Item 28: JIVE support scientists to include checking of sampler statistics as part of NME feedback. Action Item 29: JIVE support scientists to look into a scheme to estimate the quality of pipeline amplitude calibration results. Action Item 30: Friends to provide gain curves free of opacity corrections (as if taken outside atmosphere). Campbell to inform users. Also PIs of 22 GHz experiments to be informed that Onsala has a different method of calibration at 22 GHz (hot load instead of noise diode), which means that Tsys values are already corrected for opacity. Action Item 31: Campbell to determine an appropriate place to put WSRT and Effelsberg calibrator flux measurements. Action Item 32: Smythe to send email reminding stations of procedures for checking Mark 5 recording. Action Item 33: Smythe will contact Brisken to organise a teleconference with NRAO on Mark 5 software status. Action Item 34: Alef to send email to stations regarding disposal of tapes. Action Item 35: Alef to ask Mantovani if Directors can donate money to purchase spare Mark 5 backplanes. Action Item 36: All to send constraints for the next TOG meeting to Alef.