Date: September 10, 2020

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


NRAO: Jim, Walter, Justin
USNO: Megan, Lucas, Bill, Andy, Nicole, Stewart, Colin, Chris, Matt
  • 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. Any problems like a lack of fringes will still be reported to NRAO when they're seen.
      • One reobservation in August, both PT and MK were flagged as probably failed and fringes were not found. The reobservation looked okay, PT flagged as probably failed but fringes were found.
      • 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 persisted in August. Was not seen in the few August runs they did analyze.
      • Since the change to the F-series setups PT appears to be having more problems with RFI, the checkut1 script has flagged almost every run as possibly bad. A newer diagnostic tool has indicated fringes though. We will continue to use checkut1 to check on some aspects of the observation but will rely on the newer fringe check tool to determine if a reobservation is required.
      • USNO soon to have full use of increased bandwidth into correlator, USNO considering adding SC to daily intensive when the incoming bandwidth is fully available.
        • No operational issues moving to this stance, but do need to consider the impact on the interruption of Open Skies observers. No concerns for the Washington Correlator.
        • 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.
        • Is there a timeline for when the change to three stations will happen?
          • full bandwidth is now available on USNO correlator
          • no earlier start than November
      • A test was run on an N-series vex file made using "VieSched ++" to see if it would run on the VLBA system.
        • Due to using a different naming structure for the project the data was not recorded by the Xcubes so it had to be copied off of the Mark6 disk packs to the Xcubes before USNO could retrieve it.
        • There were no good Tsys values reported for all of the 13cm channels at both stations. 4cm Tsys looked okay.
        • Attempts to run a fringe check on the data was initially stymied by the different vex file format but this was corrected for. Unfortunately even though a strong source was chosen it doesn't look like there were fringes.
        • Correlation by USNO found no fringes.No clock preobs data was attached so might have had an impact? Could also be a setup issue reading the different vex file format.
          • Will need to compare a vex file made for an experiment by "VieSched++" and by VLBA's Sched to look for possible setup differences.
    • Other Intensive Observations
      • O-series test on HN-OV baseline
        • Will run simultaneous with the N-series observations but will not interrupt other observing.
        • Possible oscillation/tracking issue at HN recently detected, suspect an elevation encoder issue.
          • Only seen at low temperatures, hasn't been noticed since January.
        • Possibly expand in the future to include another baseline, nothing definite right now.
      • F-series characterization series on six 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.
      • "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 July that needed to be caught up in August.
      • The six Q-series observations in August were charged double time.
      • The second to last observation in the August request now has a project code, US003. It requested 16 hours but only used 9.5 hours of it.
      • The last observation in the August request did not use any of its requested 8 hours. It has not observed at all yet so does not have a project code assigned to it.
    • Pre-monthly request
      • October request again asks that the UD009 and UH007 observations be scheduled back to back. So far we have been able to accommodate this. The GMVA run in October will block out about a week of observing time so it might be harder to find a 48 hour window to do it.
  • 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.
      • Waiting on hardware and software updates, ETA end of July.
      • Still waiting on the firewall. Updated ETA is end of August, early September.
      • Tested and is working so will hopefully be able to transfer to the new server in October.
    • 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 finally begun, expected to be finished in early September.
        • Not done yet at this time. Fiber is in place, probably waiting on endpoint electronics install.
        • HN fiber speed expected to be 2.5 Gbps (maybe limited to 1 Gbps by NRAO hardware initially).
    • LA fiber may be at 10 Gbps when it's installed; this might impact consideration towards future use of it in baselines.
      • Work is underway, expected to be done by late September.
      • Given PT's 13cm RFI with the new N-series setups perhaps switch to using LA for them.
    • USNO needs to renew support contract for MK fiber.
      • This contract is being moved into the larger support contract (see below), will need to coordinate on handoff.
      • Will end up doing a short support contract of a couple months and then a more regular one to start after that.
      • Contract now at NAVSUP and they are combining the 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. Has been resubmitted and is moving forward.
      • NAVSUP is actively looking at it. Possibly ready to move forward with it.
    • 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.
      • No new information. It may come up in an IVS OPC which is scheduled for mid-September.
    • 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.
    • Next meeting October 8.

-- JimOgle - 2020-09-08
Topic revision: r4 - 2020-09-10, JimOgle
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