• P-series runs every other day.

• Z-Series runs approximately every other day, alternating with the P-series.
  
  • Returning to every three days in July.
  • BR phase cal problem bad enough it's pretty useless to them.
• Q-series intensive observations at MK run on weekends.
• I-series "Holiday" intensive observations at MK, substituting for Kokee on federal holidays.

• MK was out May 10 - 18 for a scheduled maintenance visit.
  • Scheduled maintenance work was May 10 - 21, finished up early.
  • P-series request for fifteen observations was reduced to eleven to account for this outage.
  • Q-series request for seven observations was reduced to five.
  • Extra project UC004 was provided by USNO to run during the maintenance period. This project was not in the request for May.
• Actual number of Q-series observations done in May was only three, files were not provided for May 20 and 21.
• Fifteen Z-series observations were requested, only thirteen ran.
• UP001 requested 20 hours in May but no files were provided.
• UF006 requested 8 hours, used 8.03 hours.
• 96 hours of backlog from March and April. 72 hours of backlog was observed in May but 48 hours of observing in the May request did not get observed so 72 hours of backlog carries over into June.

• Z-series observations going back to every three days.
• I-series observation on July 4 says observing time is 0730 UT but the IVS schedule shows it at 1830 UT.
  • If it runs at 1830 UT it will interrupt RV160 so presumably it was moved and the IVS schedule has not been updated?
  • Looks like it will be at 1830 UT.
• New project UD018 will be fixed date on the Mondays in July.
• New project US006 requested one observation of 28 hours duration. Does this have to run as a single observation or could it be broken up?
  • Probably can be broken up.
• The COOP test of the USNO backup correlator is scheduled for a non-standard day, Thursday July 13.

• 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. .
    
    • Future tests: July 13, August 2, September 13, October 4, November 8, December 13
    • June test was canceled when backup correlator was used June 2 to process I23153; the Washington correlator was unavailable due to server room work.
  • Further use of the backup correlator in the processing of P-series and Z-series observations has been proposed.
    • Eventual goal would be to see a demonstration of these being processed on the backup correlator without the involvement of any DC-based USNO personnel.
    • Some testing might involve using the VLBA correlator rather than the backup correlator.
    • Will be easier for VLBA to handle after the deployment of the e-transfer filesystem later in 2023.
    • This will hopefully transition into the ability to do bigger projects for USNO at DSOC such as the 24-hour R4 observations.
    • Initial hope is to do one P and Z series on the backup correlator in April.
      • This did not happen in April or May.
      • Let's try and do something in the next couple weeks.
      • Where to download the data to at DSOC before the deployment of the e-transfer system? Would it take up too much bandwidth at DSOC?
        • The current datacopy areas have sufficient space to do testing.
  • USNO would like to be able to check automatically if the backup correlator is up or down but are unable to do so, can NRAO set something up for this?
    • Mark Wainright working with CIS on it, no update.
• Replacements for the Xcubes (called Data Buffer Server, DBS) have started rolling out. New software will ultimately cause a change in the naming structure of data files and PFB data format will no longer be supported, instead it will be convereted on the fly to VDIF format.
  
  • DBS units have been installed at PT and MK.
    
    • LA and/or HN will be next, no dates set.
  • Software changes won't happen until all stations have had their Xcubes replaced.
• Higher speed network connections to HN and MK opens the possibility of realtime correlation of intensives.
  
  • Neither Washington correlator nor NRAO set up to do it yet.
    
    • Blocking issue for NRAO is mostly network speed into the correlator.
    • USNO is not able to directly ingest data to their correlator. Could perhaps have data downloaded to the DMZ in realtime for near-realtime correlation. Will need to be discussed internally.
      • USNO will have faster line installed in early 2023 so will start looking into the possibility after that.
        • Install of higher speed line was delayed until May.
        • Was installed in May. Still have some tuning and optimization to do on it first.
• 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 really practical at this time so expedited shipping of disk packs would be needed.
  • Record of time to correlation:
    
    • UD011AA 8 days, UD011AB 8 days, UD011AC 9 days, UD011AD 6 days, UD011AE 7 days, UD011AF 16 days, UD011AG 22 days, UD011AH 13 days, UD011AI 5 days, UD011AJ 8 days, UD011AK 8 days, UD011AL 7 days, UD011AM 10 days.
    • Two in May:
      
      • UD011AN 8 days
      • UD011AO 5 days
    • Two in June:
      • UD011AP - observed June 12, still waiting on disk pack from SC (held up in customs)
      • UD011AQ - observed June 19, disk packs en route
• New IVS session code naming structure change in 2023
  • On NRAO's side, 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, currently there are none.
    • Plans mentioned above to correlate some intensives in Socorro would not be impacted since data would be e-transferred instead of correlated from disk pack.
  • IVS will continue to use the existing shorter naming structure through all of 2023.
    
    • USNO notes they are using the longer naming structure in correlation and archiving of data but will probably hold off on using it for observations until after IVS makes the switch.
      • Might happen this fall.
  • USNO will send some representative "new style" IVS observing codes for NRAO to run through its software looking for any unexpected problems.
    • Test NT2022224AAA ran on Aug 12, 2022.
    • DiFX does have some project code length limitations, a modified trunk version of has been made for the correlation and the change will hopefully go into the next release (DiFX 2.8,which has now been released.)
      • There is an issue with Mark4 data, it does impact some USNO data (though not VLBA data).
    • SCHED also has some project code length limits but SKED and VieSched ++ may not?
    • Some minor issues were found with archiving of data and some automated emails truncated the longer project code.
      • Xcube/DBS recording software does look at project codes to determine to record or not, will need to be addressed.

Long term issues

• USNO reports starting May 2021 have seen a lot of cable cal issues in the Z series.
  • BR notably bad (affecting Z-series). It has been seen there in non-USNO observing too.
  • A maintenance visit to BR is scheduled for August 2023.
  • Have gotten even worse in pulse cal, though cable cal is not as bad now.
  • SC has started having cable cal problems too.
• NRAO will at some point begin doing data downloads during and after observations and this could conflict with USNO's own data downloads of the intensives.
  • Currently NRAO is doing downloads about once a week in a post-maintenance day test, usually nowhere near the times of intensive observations.
• Possible changes coming to login accounts on Xcube/DBS modules, moving to a group USNO account rather than using individual accounts. No ETA.
• USNO-NRAO contracts:
  
  • V3 DiFX (correlator upgrade) contract awarded in March.
    • First milestone isn't until September.
    • Some invoicing issues being worked on.
  • USNO has exercised their option on support contract.
• There's interest in having VLBA observe along with a VGOS session in "mixed-mode".
  
  • First IVS needs to move some correlation off to other correlators and then they can start considering adding more stations like VLBA to the VGOS observations.
    
    • Still working through correlator backlog, VGOS has ramped back because of that. Will be revised in early 2023.
      
      • There will be a meeting in March to see how the others are doing with their backlog. Backlog might now be with stations not correlators.
        • Backlog's been dealt with, but nothing will change until 3rd quarter. Next discussion likely in July.
• 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.
  • Possibility of adding KK to an RDV observation raised.
  • Might be able to use WZ rather than KK to get the necessary clock offset data, they are already in RDV observations. Would need data analysis results from USNO.
  • NRAO probably will wait until after new GPS receivers get installed on array.
    • First has been installed at FD this week. Second scheduled for PT in July. Might take about a year to finish the installs.
• USNO and IVS partners have challenges with creating VLBA-valid VEX files with the SKED and VieSched ++ software packages.
  
  • Why is there a need to add additional information that is not part of the VEX standard?
    • Tuning VLBA at certain frequencies requires the additional commented information, it's not found in standard VEX setups/catalogs.
  • What is the plan, if there is one, for removing the need for the additional information required by the VLBA?
    • VEX2 standard will cover the missing information for VLBA, though the scheduling software used will still need to have the right setups information.
    • Probably late 2023 before VLBA might switch to using VEX2, hopefully before 2025.
    • 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.
    • Will start testing of VEX2 on VLBA soon?

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