Date: December 10, 2020

Time: 11:00 am Mountain, 1:00 pm Eastern

´╗┐Microsoft Teams: Click here to join the meeting´╗┐

NRAO: Walter, Justin, Jim, Mark
USNO:Matt, Megan, Chris, David, Phillip, David, Matthew, Bruce, Nicole, Stuart, Lucas
  • VLBA Observations
  • Daily Observation Report (N-series)
    • Due to a time crunch at USNO they were not doing a daily analysis of the N-series correlation results so there is no feedback report for August though November. Any problems like a lack of fringes will still be reported to NRAO when they're seen. They have resumed the daily analysis on December 1st.
    • No reobservations in November.
    • 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 November 1, 2020 SC was 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.
      • We're encountering some problems with three station observations coming up short due to limitations of the SCHED software.
        • To try and alleviate some of these problems we tried making changes to the key file used to generate the observation files. These did not significantly improve things.
        • Having USNO provide daily files made with 'VieSched++' will be tested in December. Each day will have multiple files with different start times provided to make scheduling easier.
      • SC will be unavailable for the N-series observations December 9 - 12 due to a last-minute scheduling change on antenna maintenance by an outside contractor.
      • A five-station intensive plan is being developed that would replace the N, O and F series intensives. This could be a significant issue with interrupting open skies observing so will need discussion between NRAO and USNO.
    • Discovering that KK and WZ both take Christmas and New Years Day off from running their intensives brought up the question in operations of whether or not NRAO is required to run its N-series observations on the two days where it is otherwise shut down for the holidays, Thanksgiving and Christmas. Since the start of USNO observations we have made operators come in and run the N-series observations (and an I-series in the case of this past Thanksgiving).
      • There is a need for intensives on those days since no one else is doing it those days. Original contract did specify daily, no exceptions. KK and WZ aren't under contract so it's a different situation.
  • 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.
        • Elevation encoder replaced while repair crews were on site for azimuth wheel replacement in early October.
    • 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.
    • "Holiday" intensive observations at MK
      • Project code for these observations will be IYYDOY.
      • Will be substituting MK for Kokee on federal holidays in 2020.
        • There will not be intensives run on Christmas or New Years Day as both WZ and KK take those days off.
    • 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.
      • Some last minute additions for December will be submitted for Dec 19, 20 and 27. Additional observations for January 2021 will be requested as well.
  • Post-Monthly Report Review for November
    • No backlog from October that needed to be caught up in November.
    • UD012 requested 16 hours in November, only used 6.32 hours.
  • Pre-monthly request for January 2021
    • Looks pretty straightforward, nothing unusual.
  • 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.
    • USNO reported that they're unable to get to the newly assigned tsunami port at PT (port 46343) but are still able to get to it through the old port (46335). The new tsunami ports at all of the other stations are accessible.
      • Walter will file a helpdesk ticket for NRAO CIS to look into the problem.
    • 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.
    • HN-MK is looking to be a more promising baseline than the others USNO has data for. After current time crunch is over USNO will analyze which baselines will be best for future intensives.
      • New five station intensive being developed will cover this.
    • 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 going through starting Dec 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 starting Dec 2020.
      • A follow-on to the correlator support contact is in place for six months, started September 2020.
    • 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.)
    • Data ingest of IVS data to NRAO/Socorro in support of USNO backup correlator operations has been lightly tested.
      • Desire to do a monthly test of the backup correlator by correlating a WZ-KK intensive.
      • A test correlation of a KK-WZ observation was performed by USNO on the backup correlator in late November.
      • Time to move ahead with making this a regular test?
        • Data copying will need to be coordinated, probably handled by VLBA operations.
        • 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.
    • 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.
    • 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 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 open skies instead.
      • A letter to Mark McKinnon expressing interest in doing this could get the necessary discussions started.
      • This was brought up at VLBA coordination meetings in November. There was some confusion because there are actually two observing modes called Y3 for the VLA so some clarification from USNO on what they're interested in was desired.
      • Mark Claussen suggested they 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.
      • It may come up in an IVS OPC which is scheduled for mid-September.
        • 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.
      • 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.
Next meeting January 14, 2021.

-- JimOgle - 2020-12-07
Topic revision: r3 - 2020-12-10, JimOgle
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