• P-series runs Tuesdays and Thursdays around the time of I-series intensives, Saturdays and Sundays after Q-series intensives.
• NZ-Series runs approximately every three days.
  
  • BR cable/phase cal problem. Comes and goes, leading theory is thermal expansion and contraction of cables.
  • SC also has a cable cal problem but is slightly different in effect and doesn't seem to be due to thermal issues like at BR.
• Q-series intensive observations at MK run on weekends.
  • GSI now supports using etc/etd for file transfers but attempts to install the software on the DBS at MK has so far failed to work so we continue to use tsunami.
• I-series "Holiday" intensive observations at MK, substituting for Kokee on federal holidays.
  
  • Kokee will be down for some signal change and receiver upgrades, currently scheduled for April 2026. MK will substitute for it during that time.
  • Hopefully early April as MK is needed for GMVA session April 16-21.
  • Could be down for 4-6 months? Work might only take one month but checkout and testing could take longer. USNO should know more next week.

• UD020 incremented to UD021, UG006 incremented to UG007
• UG007 has two sessions instead of the usual one.
• UF007 initially not in requested, added back in late. It should have had a time charge of 2 but the revised request still has it at a 1.
• Four P-series observations were canceled due to bad weather or mechanical issues.
• UD021A did not run, backlog to February (ran February 6).

• GC040 will substitute for UD021 in February.
• UF007 added back in after initially being left out.
• COOP test late addition, scheduled February 19.

• COOP test late addition, scheduled March 19.
• Another observation being added, revised request to be sent.

• V2 correlator status:
  • Contract extension expected for 5 months, to 6/22/26.
    • NRAO visit to USNO the week of February 2 included discussions regarding V2 maintenance transitions and plans for backup operations correlations on VLBA correlator.
    • Between now and June, NRAO and USNO will be collaborating on a handover process.
  • Tuesday 1-3pm (Eastern Time) Maintenance Window weekly patches continue, with weekly reporting to USNO at the conclusion of each patch.
    • Window was revised to match normal business hours for DC team.
  • 4 spare storage drives remain available at USNO.
• V3 correlator status:
  
  • USNO front office has successfully navigated the DoD Systems and NRAO has been paid for Milestone 3. Milestone 4 invoice now in progress.
  • Next milestone 5 will be delivery of design documentation for cybersecurity audit process, expected this month.
  • NRAO team began construction at DC for the subset of devices that shipped for the V3 correlator. Additional hardware (JBODs) is en route to USNO.
  • The V3 prototype 2 is being assembled at DSOC, toward testing of processing speed and authorization for Dell to proceed with full DC server fabrication.

• Expiration of the V2 support contract
  • Contract extended from January to June 2026.
  • COOP tests and uses will eventually need to migrate to the VLBA correlator, probably using the e-transfer system.
    • Currently e-transfer does not have set procedures for downloading from VLBA stations to Socorro.
    • Hardware upgrade of the VLBA correlator could involve a second head node devoted to USNO needs.
    • Procedures for handling use of the VLBA correlator by USNO will need to be developed.
    • COOP likely to be renamed to BACKUP.
    • Additional use of VLBA correlator for processing of P-series and NZ-series observations also part of the discussion.
      • Use of VLBA correlator for processing of a P-series was tested by Walter with P2026043 (ran February 12).
        • Has been correlated and sent on to USNO for analysis next week.
• Data ingest of IVS data to NRAO/Socorro in support of USNO V2 correlator ("backup correlator") continuity of operations (COOP):
  • We will do a monthly COOP test of the V2 correlator by correlating a WZ-KK intensive.
    • See above about moving COOP/BACKUP to using the VLBA correlator in the future.
    • February test scheduled for the 19th.
    • March test scheduled for the 19th.
• DBS software changes
  • xcuberec program which records the data on the DBS will be replaced by sendit. This will cause a change in the naming structure of data files and the PFB (Mark5B) data format will no longer be supported, instead it will be converted on the fly to VDIF format.
  • Initial testing of sendit has begun by running it in parallel with xcuberec at MK. Once the software is running at HN we will be ready to do some comparison testing when USNO is able to do a double correlation.
    • Is USNO ready to do double correlation testing? P2026013 was successfully recorded by both xcuberec and sendit.
    • Emailed Bruce with location of the sendit data for P2026013.
      • Has it been correlated? Not yet, but data was downloaded. Should get correlated in the next couple weeks.
• VLBA e-transfer system
  • RDV observations having the non-VLBA stations e-transferred.
  • Anthony Sowinski PoC for NRAO.
  • KK having issues getting etc/etd to transfer to WACO and VLBA. But they can transfer to Haystack okay?
• Is it possible to reduce the latency on 24-hr geodetic USNO-only sessions, with a goal of a latency between the completion of observation to analyzed result under 7 days?
  • E-transfer not practical at this time so expedited shipping of disk packs is needed.
    • Now that e-transfer is working, should be consider trying it with UD011?
      • Under consideration, would require some coordination around observing and bandwidth concerns especially with the slower stations like SC. Also no procedures in place yet for e-transferring data from VLBA stations to DSOC.
  • Might be limited to just attempting it for one of the two UD011 observations per month.
  • Record of time to correlation:
    
    • first year of observations (UD011 AA - AR) average time was 9 days. (Specifics can be found in minutes of previous meetings.)
    • second year of observations (UD011 AS - BQ) average time was 12 days counting all observations, just counting the one observation a month we put a rush on the disk pack shipping the average time was 9 days.
    • third year of observations (UD011 BR - CO) average time was 15 days counting all observations, just counting the one per month with rush shipping the average was 13 days.
    • fourth year: UD011 CP - 12 days, CQ - 15 days, CR - 13 days, CS - 13 days, CT - 29 days (problems with correlator updates at DSOC slowed things down), CU - 16 days, CV - 22 days, CW - 20 days, CX - 19 days, CY - observed Jan 26, CZ - observed Feb 2
• Current DiFX release (2.9)
  • One issue involving VGOS data in HOPS package still being worked on, a workaround is in place. A new version of HOPS is expected to resolve the issue, still in development. Might be ready for testing in the spring.
• VEX2
  • Vex2 standard will cover missing tuning information that SKED and VieSked++ aren't able to include.
    • This information will still be required but VEX2 will have a space for it so manual editing won't be needed.
    • Things are okay right now with standard USNO setups and observations, could become an issue if USNO starts using non-standard setups in new observations.
    • USNO has been sent vex2 samples, will have them send NRAO a file to test and make sure it works.
      • NRAO has received samples, no test file yet.
    • Question from Ed H at Goddard about status of vex2, and any shortcomings that might push an incremental VEX2 release? USNO has one thing they'll bring up.
      • Some progression in IVS meetings, but issues remain to be addressed particularly with old files and if conversion will be necessary.
  • NRAO is using VEX2 now.
    
    • Sched 12 is out, NRAO has switched to using vex2 internally.
    • Vex 1.5 will remain supported but once VNDA is installed and running in 2026 NRAO will probably end supporting v1.5 after a year.
      
      • Should start a test phase on USNO-provided vex files with vex2 now rather than later.
        • Problems reported by USNO with fourfit and vex2, there's a workaround.
        • vex2 not supported by the mark4/HOPS data path? This and fourfit might be the same issue?
        • for the immediate future the vex 1.5 files can be used to avoid the fourfit and mark4 issues.
• Installation of new GNSS/GPS receivers at VLBA sites.
  
  • Receivers have been installed at all sites but are not in use yet.
    • All stations have been seen to transmit data but it's not usable by NRAO yet.
    • Also waiting on firmware updates to address using them for timing purposes.
      • Done, but not all stations are working identically so some issues are still being tracked down.
      • Nine of the ten have valid time offset code running. One more update before end of calendar year hope to have all ten running. Would like to have six months of running data from the sites before they declare it fully operational (so mid 2026?). VLBA would be able to start own analysis during that time.
• Mixed mode correlation
  • Have tried mixed-mode correlation on VLBA correlator starting with RV169 but with no success.
    • Probably giving up on having VGOS stations in RDVs, not getting good support from Haystack and WACO on figuring out how to make it work on VLBA correlator.
    • Probably need to try again with a small data set that USNO correlates first to show it works and then send the data to VLBA to try correlating it.
• USNO asked about getting CASA to read pulse cal data the way AIPS does, it would help with their imaging efforts on weak astrometry targets at higher frequencies.
  • A CASA developer has been assigned and work has started on it.
  • Hoping to have a test version available in early December.
    • Test version available, being worked with, won't make it into the next release of CASA but hopefully will be in the next one (April 2026).
• Are the monthly feedback reports from USNO still useful?
  • Chris Dieck leaving current position so someone else at USNO would need to take over.
  • Typically if something bad comes up it gets brought to NRAO's attention right away not in the feedback report and USNO has its own tracking system for problems.
  • Does NRAO get any value from the reports? (Jim does look at them.)
  • Also, are they required by contract? It was back in the 2012 contract but is it still in current contracts?
    • Walter think that if anywhere it would be in the old implementation plan, not the MOA, so probably isn't required.

Long term issues

• USNO reports detecting a drift in MK baselines beginning mid-2023 and still happening.
  • Approximately 0.1 microsecond per day drift, works out to about 0.25 cm/year.
  • It's seen in the NZ series but not P-series, so maybe a correlation or analysis issue rather than with MK itself.
  • Phil Cigan did an analysis and found it to not be significant so this can be dropped.
• Realtime correlation of intensives
  • Fast network connections at HN and MK make it theoretically possible but neither NRAO nor USNO are set up at the correlator end to do it yet.
  • NRAO could attempt this but there will be some limitations - VLBA stations only, limited to observations that record at 512 Mbits/sec or less and NRAO would need help from USNO in determining sessions, creating files and looking at the output.
  • An additional consideration is that while these observations would still record to Mark6 disk packs, they would not record data to the DBS units so would not be easily downloadable should the realtime correlation not work.
  • USNO will wait for the v3 correlator before they can start considering realtime correlation.
• .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?
  • Walter reached out to some people, says it looks like it would be a bigger effort than anticipated.
    
    • Possibility of adding KK to an RDV observation instead raised..
      • KK will be in the April 2024 RDV observation so could get data from that.
        • RV165 observed April 24. Has been correlated.
        • After USNO (or NASA?) does analysis a copy of the clock offsets can be provided to VLBA for comparisons.
          
          • Analysis finished, but didn't include VLBA stations so still need to do that and get the info to NRAO.
        • Kokee does have a different maser compared to last time VLBA correlated with them, might have an effect?
    • VLBA thinks it will have to wait until after all ten stations have received new GPS units (and they're all in use).
      • Prioritization of this and other lingering issues should be considered once we can start looking at this again. Maybe mid to late 2026?
    • Moving to VNDA will also change VLBA delays slightly, so it'll probably have to wait until after that's in place as well.
      
      • The RV165 clock offset data would be useful for a before and after comparison, but it would not be used to adjust the VLBA offset. A second observation like RV165 would be needed so we could make the comparison.
      • VNDA timescale looks to be lining up with the v3 correlator so we'll just wait for both of those to be completed.

• 600 Mbps minimum at each site
• 1 Gbps at PT, KP, OV, NL. FD
• 5 Gbps at HN
• 10 Gbps at LA,BR, MK
• 600 Mbps at SC (download up to 400 Mbps) - possibility it could be going up to 1 Gbps