• No reobservations in April but N21120 was not run in favor of starting the new P-series a day early.
• Missing scans - USNO reported problems with scans missing in the Xcube data, which NRAO found do get recorded to the Mark6.
  
  • Missing scans have happened at all three stations (SC,PT,MK). It is likely that it will also be seen at other stations.
    • Since the start of the new Z series it has been seen at HN. Z21131 for example had only 39 scans on the Xcube but 47 on the Mark6 pack. But the prior two Z-series runs weren't missing any and neither was the one after it.
  • Could be an issue with scans coming in without enough of a gap for the Xcube to be caught up on recording one scan and it misses the next one. USNO could try Increasing gap time between scans as a short-term fix.
    • Gap time increase was tried with the N-series in late April and the P and Z-series but as noted it is still being seen.
    • A couple options are to increase the gap time even more or two twiddle a couple 'knobs' in vieSched++ to try and reduce some extraneous recording.
  • Xcube replacement plan is going ahead but there are some contractual issues for funding with number of stations covered by USNO slowing it. Target is still in June, possible but July seems more likely.
• A five-station intensive plan is being developed that will replace the N, O and F series intensives but not the P-series.
  
  • There will be a four month test period beginning May 1st to characterize the five-station baselines.
    • The new five station intensive will run every other day. The desired time range is 00h - 08h UT in order that USNO will be able to correlate it first thing in the morning but they will accept it being run outside that window.
    • The five station intensive will not interrupt other observing.
    • Up to three stations can be lost from an observation as long as it is not reduced to just the OV-BR baseline.
    • Files will be created with vieSched++ instead of sched.
    • The N, O and F series observations will end April 30th.
    • Project code for the five-station intensive will start with Z (ie, Z21121)
    • Does USNO want the five-station intensives recorded in the daily observation spreadsheet? Sure.
  • During the test period the P-series observation will take the place of the N-series as a daily intensive run concurrent with the IVS intensive.
    • The P-series will remain 1.5 hours in duration. Files will be created with vieSched++ instead of sched.
    • It can interrupt other observing the way the N-series currently can.
    • Due to the longer duration the time window for the observation will increase slightly to 17h15m - 19h45m UT.
    • First run of the new P-series was a day early on April 30. There were setup problems with the provided files producing bad Tsys calculations but fringes were seen.
    • Daily observation spreadsheet will start recording the P-series intensives.

• O-series test on HN-OV baseline
  
  • Will run simultaneous with the N-series observations but will not interrupt other observing.
  • Will end when the new five station intensive begins, see above.
• F-series characterization series on six of the VLBA stations every two weeks.
  
  • Will end when the new five station intensive begins, see above.
• P-series intensive observations roughly every other day on the HN-MK baseline
  
  • Beginning May 1st will run daily in place of the old N-series observations, see above.
• I-series "Holiday" intensive observations at MK
  
  • MK will substitute for KK on federal holidays.
• Q-series MK-WZ backup observation series
  
  • Involves a post-observing procedure for operators to copy the data to correlator in Japan.
  • Was restarted in late June 2020 due to the Ishioka station being unavailable, last observation scheduled for May 16.

• No backlog from March that needed to be caught up in April.
• 'UD012/US005' project requested 16 hours in April, only used 8.4 hours.
• Fifteen P-series were requested in April, even with the early start of the new P-series on April 30 only thirteen ran.
• UC002 only got two of its three observations done in April, 14 hours will carry over into May as backlog.

• Nothing new or unusual seen in the request.

• USNO will not be using Microsoft Teams after our June meeting so an alternative will need to be found.
• NRAO is starting to do more data downloads during and after observations and this could conflict with USNO's own data downloads of the intensives.
  • Currently NRAO is doing it mostly with a once a week test but it will eventually ramp up.
  • In an effort to coordinate download times between the two groups a small group to discuss it will be formed, probably two people from each side.
• A minor 'DiFX' release went out in October (2.6.2) and will be installed on the VLBA correlator. USNO is currently using 2.6.1 on their correlator(s), waiting on internal approval to move to the new version.
  • It has been approved, not installed yet.
• 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.
  • Bruce Thornton reported that he has not been receiving any emails from the ut1 list recently.
• USNO-NRAO contracts:
  • USNO renewal of MK fiber support contract currently at NAVSUP and being combined with other support contracts.
    • Follow-on contract for six months started December 2020.
    • Might be moved into operational costs/general support.
  • Networking support contract being worked on, might involve changing some dates to spread out USNO contract renewals over different times of the year.
    • Six month extension started December 2020.
  • A follow-on to the correlator support contact is in place for six months, started September 2020.
    • Contract ended March 22. NRAO response to the Request for Proposal was expected in early April.
      • Extension was granted and we've transitioned to the new contract through the end of 2021.
  • Interest in merging the support contracts into the interagency agreement.
    • USNO will bring this to NSF.
• Data ingest of IVS data to NRAO/Socorro in support of USNO backup correlator operations:
  • We will do a monthly test of the backup correlator by correlating a WZ-KK intensive. Nominally scheduled for the first Wednesday of the month.
    
    • May test was supposed to be on May 5 but no one remembered to do it so it was delayed to May 12.
  • Data copying will need to be coordinated, probably handled by VLBA operations. Instructions for the operators are pending.
    
    • April 7 test - an initial glitch downloading WZ, operator error, otherwise went okay.
    • May 12 test - data transfer from WZ keeps failing.
  • Test correlator is only correlating on one node instead of four, that needs to be figured out.
    • ACTION: still an issue, NRAO to investigate. Update? Will check with Mark Wainright.
    • Fringer and correlator can't download data directly, has to be run through gygax first.
    • Synching files also has to be side-loaded through gygax which further complicates process.
    • The ftps download of files through gygax (above two bullet points) stopped working this week.
      • ACTION Something changed on the NRAO side, USNO will contact NRAO helpdesk. Email to helpdesk didn't seem to go through, USNO will resend.
  • A bigger test, hopefully quarterly, of a 24-hour R4 observation is desired. NRAO would like a requirement document to figure out what needs to be done.
    • ACTION: USNO to provide the requirements in two groups. One with the disk space details, and a second with station connection details.
      • Disk space requirements have been received by NRAO.
    • ACTION: NRAO acquire additional storage capacity in support of requirement.
      • Waiting on funding.

Long term issues

• 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. Currently new data is going into both, sometime soon it will switch to only going into the new archive.
    • Requirements have been set, still several months at least until we switch to just the new archive.
• There's interest in having VLBA observe along with a VGOS session in "mixed-mode".
  
  • Heard from IVS OPC in November. First they need to move some correlation off to other correlators and then they can start considering adding more stations like VLBA to the VGOS observations. Possibly start looking into it mid 2021.
• New IVS session code naming structure
  • There is likely to be a change to format of the IVS "session code", but maybe not until later in 2021 or 2022.
  • New IVS codes will be similar to existing codes but perhaps slightly longer, for example "NYYYYDOYNN". USNO & Goddard had a 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 only affect any intensives which get correlated in Socorro, something that will end when the switch to the five-station intensive observation eliminates the intensives that are correlated by NRAO instead of USNO.
  • Walter Brisken suggested running an end to end test to make sure all of the software can handle the longer names.
    • NRAO can probably do an end to end test with one of the old intensives such as the F-series, it will take more software work on USNO side depending on what IVS comes up with.
  • Was discussed in the March IVS workshop, there is renewed interest in doing this. Possibly some action on it this year.
• Peculiar delays - 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 after COVID.
• 'DiFX' Workshops are happening. Walter talked about real-time VLBI Feb 18.
  • Probably will be another one later this year.

• 200 Mbps minimum at each site with 190 Mbps the practical limit due to required overhead.
• 1 Gbps at PT,KP,MK
• 2.5 Gbps at HN
• 10 Gbps at LA