Date: February 11, 2021

Time: 11:00 am Mountain, 1:00 pm Eastern
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Conference ID: 168 008 659#

NRAO: Justin, Walter
USNO: Bruce, Chris, Megan, Nicole, Matt, Lucas, Stuart, Phil, Phillip
  • Daily Observation Report (N-series)
    • Two reobservations and one substitution in January; first reobservation was due to no fringes seen by operations in post-processing, second was due to SC being unavailable and MK's FRM not moving so it was redone with HN-OV, the substitution was similarly because SC and MK were unusable but that was canceled before it ran and was replaced with another HN-OV observation.
      • The first HN-OV observation failed to find any 4cm fringes, this turned out to be an ellipsoid problem at OV which was fixed in time for the next day's observation.
    • Some observations in July 2020 were reported as having cable cal problems at PT, cause unknown. Due to the temporary halt in daily analysis between August and December it's unknown if this has persisted; has the problem been seen now that analysis has resumed? -- seen two days in August, none in December. Intervening months still being analyzed.
    • SC was unavailable for observing January 23 - February 2 due to a broken elevation gearbox.
    • When we began using SC again on February 3 we noticed internet communication problems in the hours after the observation ran, where a couple times we've been unable to download any data to do a fringe check and we're not receiving some of our monitor data. We're assuming that this time frame is when USNO is downloading the data? We were not having these problems earlier in January so something seems to have changed recently. Is USNO still using the same procedures and settings to download the data? Our connection speed is dropping from 200 Mbps to less than 50 Mbps and the site tech at SC reports that he doesn't even get 1 Mbps.
      • USNO does download at 180 or 190 Mbps as soon as the data is available on the xcube. Walter suggests waiting for the observer's report and transferring at 175 Mbps. USNO will start to do that.
    • A five-station intensive plan is being developed that would replace the N, O and F series intensives. (But not P-series, that runs separate to mid-July 2021) This could be a significant issue with interrupting open skies observing so will need discussion between NRAO and USNO.
      • NRAO's suggestion is that if an interruption of an open skies observation is required it would be made up of three (SC-PT-MK) rather than the five stations, matching which is currently in practice.
      • A larger observing window than the current two hour window could help reduce the number of interruptions required.
        • Perhaps a stated strong preference with an allowable window around it.
      • There may be a desire to do the N-series and the five-station intensive at the same time to better characterize the five-station series before switching to it as the primary series.
        • Options are to alternate (4 N-series and 3 5-station session per week) or layer (N series every day with 3-4 5-station sessions each week).
      • 5-station observations would not commence before May 1st, 2021.
  • 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 2020.
        • Elevation encoder was due to be replaced while repair crews were on site for azimuth wheel replacement in early October but this did not happen.
        • Has not been reported so far this winter but it also hasn't been as cold.
    • 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.
      • Will end in mid-July 2021.
    • I-series "Holiday" intensive observations at MK
      • Project code for these observations will be IYYDOY.
      • MK will substitute for KK on federal holidays.
    • Q-series MK-WZ backup observation series
      • Project code for this observation will be QYYDOY.
      • Involves a 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 into 2021.
      • Some last minute additions for January 2021 were requested, these were charged double-time.
  • Post-Monthly Report Review for January
    • No backlog from December that needed to be caught up in January.
    • UD012 requested 16 hours in January, used none.
  • Pre-monthly request for March 2021
    • Looks pretty ordinary.
  • Open issues
    • A minor 'DiFX' release went out in October and will be installed on the VLBA correlator. A good fraction of the changes in this release are related to difx2mark4. USNO will stick with 2.6.1 for now and check out the changes to difx2mark4.
      • Seems that most of the updates result in minor changes to the data quality so they could probably move to the update but still want to check things out a bit more.
        • USNO just needs internal approval to move to 2.6.2.
    • 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.
      • Recently emails to have been bouncing back as unknown addresses but not all of them, like only one a month; should these all be pre-emptively switched to addresses?
    • 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.
      • 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.
        • The end of this contract is approaching on March 22. Need to address this soon.
      • Interest in merging the support contracts into the interagency agreement.
        • ACTION: USNO to 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 Wednesday before these monthly meetings.
        • February test delayed one week due to a change in KK's network configuration.
          • VLBA and USNO both working to be able to transfer data. USNO has had success, VLBA will reach out to USNO for assistance getting transfer setup working. USNO will push data to NRAO if they NRAO is not able to retrieve data from KK by February 17.
      • Two correlations of a KK-WZ observation have been performed by USNO on the backup correlator, in November 2020 and January 2021.
        • Test correlator is only correlating on one node instead of four, that needs to be figured out.
          • Still an issue. Action to VLBA.
        • Software not completely set up yet on USNO's side.
          • Post-correlation software is now all squared away and works.
        • Data copying will need to be coordinated, probably handled by VLBA operations. Instructions for the operators are pending.
        • Should the correlator test be mentioned on the monthly observing requests? It would help coordinate efforts by specifying which KK-WZ observation is to be correlated.
          • Yes. ACTION: USNO (Lucas) will add this to the monthly report. This notification will be particularly important when planning the R4 tests.
        • A bigger test of a 24-hour R4 observation is desired, NRAO would like a requirement document to figure out what might need doing at our end.
          • ACTION: USNO to provide the requirements in two groups. One with the disk space details, and a second with station connection details.
          • ACTION: NRAO aquire additional storage capacity in support of requirement.
    • (long term issue) 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.
    • (long term issue) USNO has interest in exploring the recently announced VLBA+Y3 observing mode. What would be needed to move forward on exploring this?
      • This is RSRO so an external proposal will be needed.
      • A number of scheduling and technical issues with the VLBA+Y3 concept are still being sorted out at NRAO.
      • How will this fall under the USNO's 50% VLBA time since this is not fully VLBA? Probably have to go under open skies time instead.
      • A letter to NRAO expressing interest in doing this could get the necessary discussions started.
      • Mark Claussen suggested USNO might start with VLBA+Y1 observing mode since it's an already established mode while the VLBA+Y3 is still in development.
    • (long-term issue) 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.
      • 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.
    • (long-term issue) 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. 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.
      • 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 primarily only affect the O, P and F-series observations which get correlated in Socorro. This might become moot after moving to a five-station N-series observation as it will eliminate the O and F-series observations (and P-series when they end.)
      • Walter Brisken suggested running an end to end test to make sure all of the software can handle the longer names.
    • (long term issue) 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.
    • Fiber Status at each site:
      • 200 Mbps minimum at each site with 190 Mbps the practical limit due to required overhead.
        • 1000 Mbps at MK, PT, KP
        • 2.5 Gbps at HN
        • 10 Gbps at LA
    • DiFX Workshops are happening. Walter will be talking about real-time VLBI Feb 18 @ 2200 UTC.
Next meeting March 11, 2021.

-- JimOgle - 2021-02-08
Topic revision: r4 - 2021-02-11, ChristopherDieck
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