Date: October 8, 2020

Time: 11:00 am Mountain, 1:00 pm Eastern
Phone: 434-817-6468 ext 228111#


NRAO: Jim, Walter, Justin
USNO: Bruce, Stewart, Philip, Matt, Andy, Chris, Megan, ??
  • VLBA Observations
    • Daily Observation Report (N-series)
      • Due to a time crunch at USNO they are currently not doing a daily analysis of the N-series correlation results so there is no feedback report for August or September. Any problems like a lack of fringes will still be reported to NRAO when they're seen.
      • One reobservation in September, fringes were not found. The reobservation looked okay.
      • Some observations in July were reported as having cable cal problems at PT, cause unknown. Due to the halt in daily analysis it's unknown if this has persisted. Was not seen in the few August runs they did analyze.
      • Beginning in November SC will be added to the daily N-series intensives making it a three station observation.
        • Potential future multi-station (~5 stations) intensives would probably not preempt other observations, and would therefore require a larger observing window than is currently present on the daily intensives.
      • A test was run on an N-series vex file made using "VieSched ++" to see if it would run on the VLBA system.
        • There were no good Tsys values reported for all of the 13cm channels at both stations. 4cm Tsys looked okay. No fringes were seen in the one scan we sampled.
        • Correlation by USNO found no fringes.No clock preobs data was attached so might have had an impact?
        • Will compare a vex file made for an experiment by "VieSched++" and by VLBA's Sched to look for possible setup differences to explain the failure.
          • Example files were provided, W. Brisken is examining them.
          • Followup test attempts in early October have been stymied by problems at PT stemming from a site power failure.
    • Other Intensive Observations
      • O-series test on HN-OV baseline
        • Will run simultaneous with the N-series observations but will not interrupt other observing.
        • HN suffered an azimuth wheel bearing failure on September 25 and is unusable so the O-series observations are on hold. Return to service possible at end of the week.
        • Possible oscillation/tracking issue at HN recently detected, suspect an elevation encoder issue.
          • Only seen at low temperatures, hasn't been noticed since January.
          • Elevation encoder swap planned while repair crews are on site for azimuth wheel replacement.
        • Possibly expand in the future to include another baseline, nothing definite right now.
      • F-series characterization series on five of the VLBA stations every two weeks.
        • Project code for these observations is FYYDOY.
      • P-series intensive observations roughly every other day on the HN-MK baseline
        • Project code for these observations will be PYYDOY.
        • Using the same setups as the other runs but duration is 1.5 hours instead of 1 hour.
        • HN suffered an azimuth wheel bearing failure on September 25 and is unusable so the P-series observations are on hold. Return to service possible at end of the week.
      • "Holiday" intensive observations at MK
        • Project code for these observations will be IYYDOY.
        • Will be substituting MK for Kokee on federal holidays in 2020.
          • Next session will be Columbus Day, October 12.
      • MK-WZ backup observation series
        • Project code for this observation will be QYYDOY.
        • Involves a new post-observing procedure for operators to copy the data to correlator in Japan.
        • Was restarted in late June due to the Ishioka station being unavailable, continuing through the end of calendar year 2020.
    • Post-Monthly Report Review
      • No backlog from August that needed to be caught up in September.
      • US003 requested 16 hours in September but only used 4.5 hours.
    • Pre-monthly request
      • November request changes the N-series daily intensives to using three stations; SC, PT and MK.
      • test run of a three-station N-series will be done in October to make sure USNO correlator's new firewall won't interfere with transfer from SC.
  • Open issues
    • A minor 'DiFX' release is expected to go out next week and will be installed on the VLBA correlator. A good fraction of the changes in this release are related to difx2mark4. Will USNO want us to use the current version of 'DiFX' instead of the new release to correlate any of their observations?
      • USNO will check on the difx2mark4 changes. Will stick with 2.6.1 for now.
    • USNO emails to ut1 list are not being forwarded along to other USNO people.
      • Mail is being blocked at the Dept. of Defense level. A possible fix is being tested.
    • USNO is moving to new ingest data server and IP address is not working even though it's on NRAO's whitelist. USNO reports attempts to transfer data to the .179 address does not work. Looks like problem might be firewalls at USNO end.
      • New hardware and software tested and is working so will hopefully be able to transfer to the new server in October.
      • Have transferred to new server, working well.
    • HN-OV baseline is more precise than any of the others USNO has data for, not sure why. Plus with all the recent problems showing up at PT maybe when fiber available to HN switch the N-series to them and PT-MK to the O-series?
      • HN fiber work has been completed.
      • HN fiber speed capable of 2.5 Gbps, might be limited to 1 Gbps by NRAO hardware initially.
      • If switch to using HN-OV baseine for the N-series is still being contemplated, would SC be included in the HN-OV observations as it will be for the PT-MK baseilne starting in November?
        • HN-MK actually looks most promising baseline. After current time crunch is over USNO will analyze which baselines will be best for future 3-station intensives.
    • LA fiber may be at 10 Gbps when it's installed; this might impact consideration towards future use of it in baselines.
      • Fiber work is completed? Awaiting installation of new NRAO network hardware.
    • USNO needs to renew support contract for MK fiber.
      • Contract now at NAVSUP and they are combining it with the other support contracts.
    • Networking Support Contract: Contract will be renewed.
      • Working on renewal, might involving changing some dates on it to avoid bunching all USNO contracts up at the same time of year. VLBA might all be bundled together at a different date. Moving forward.
    • A follow-on to the correlator support contract is being worked on. Walter will coordinate with USNO for NRAO's side.
      • NAVSUP is actively looking at it. Possibly ready to move forward with it.
      • Successfully negotiated and already in use. Only for six months.
    • Transition to Mark6 recording system at VLBA is done, including 4 Gbps capability.
      • Tests for transitioning to the higher data rate, perhaps with C-band, will be considered. (Though C-band has ionosphere problems.)
    • No CONT2020 session this year. A proposed "mini-CONT" fell through and will not happen either.
      • There's interest in having VLBA observe along with a VGOS session in "mixed-mode". But there's apparently some support problems with latest version of 'DifX' correlator software and VGOS, more technical discussions need to be held to determine what could be done. Some discussion has happened, may not be as big of a problem as initially thought.
      • It may come up in an IVS OPC which is scheduled for mid-September.
      • No information from the IVS OPS yet.
    • New IVS session code naming structure (long-term issue)
      • There is likely to be a change to format of the IVS "session code", but maybe not until 2021. As the USNO works to make the VLBA intensives look like IVS sessions we want to discuss what impacts such a change might have on this effort. This particularly relates to the 'exper_name' in the .vex files.
      • Intensives are all now using the xYYDOY naming format (ie, N20001, O20001, etc)
      • New IVS codes will be similar to existing codes but perhaps slightly longer, for example "NYYYYDOYNN". USNO & Goddard have discussion about it, length will be more than six characters. NRAO has already used some seven character length codes (such as "N20014B") without it causing any problems.
        • Scheduling OMS program was tested, it will support up to at least ten characters for projects.
        • The Mark6 disk pack shipping/tracking program Packtrack has some problems with lengthy project codes but there are workarounds. This would primarily only affect the O, P and F-series observations which get correlated in Socorro.
    • Peculiar delays (long term issue) - VLBA has a delay compared to Kokee that perhaps should be checked out. Maybe put some VLBA stations into a KK observation as tagalongs so comparisons can be made. Walter reached out to some people, says it looks like it would be a bigger effort than anticipated and may have to wait until things return to normal.
    • Test of data transfers from Wetzell of intensive observation data held up a bit by getting some ssh configurations done on NRAO end.
    • Possible issue raised with accessability of USNO data in the VLBA legacy archive. Any way to put in a request people who do access the data to properly credit USNO and limit access?
      • Probably not much can be done with legacy archive, new archive system will have more potential.
    • Next meeting November 12.

-- JimOgle - 2020-10-05
Topic revision: r3 - 2020-10-08, JimOgle
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