LBA Correlator & Operations

LBA’05 Ops mtg

Hobart 8 Feb 2005

Tasso Tzioumis

Correlator Operations

• Part-time (3 days/week) correlator operator– Gary Scott ( 3 year term appointment)– Flexible hours; present most week days– Absentee correlation - most Observns– PIs still encouraged to come and correlate,

especially for “special” observations– Also assists with tape handling– Preliminary check of data in AIPS

• ATLOD - load data• Plot and inspect visibilities and spectra (VPLOT, POSSM)• Plots on experiment FTP area - web accessible

– Further checks? (FRING, ANTAB….)

S2 Tapes

• ~ 1600 tapesets on web tape list• ~ 1200 tapesets are LBA (+ CA VSOP)• ~ 1100 tapesets in unreleased observations!!!!• 30-50% in pulsars (v041,v088,…)• Only 16 observations never correlated (100

sets) + 10 partially correlated. Problems or specials?– Will contact PIs but many obs are old

• Uncorrelated backlog mainly eliminated• Recent observations correlated quickly

Tape release?

• Need 80-120 tapesets /session• Re-using recent observations (e.g. V131)• Need to “free” more tapesets• PIs need to inform us when release ok• Data Quality checks at correlator.

– Sufficient to release tapes??– What other checks PIs want?– Define time limits?

Correlator issues

• Tape release• S2 transport/tapes unreliable

– Synch lost more often – Old tapes worse– Transports aging– S2 Electronics maintenance problematic Correlation more “labour-intensive” and slower

– Tape aging --> unplayable old observations?

Correlator lifetime?

• LBA correlator and S2s aging fast• No S2 support from Canadians• May need to “cannibalise” units to fix others

– Limited correlator inputs?– Replace S2s at observatories with disks?– Develop disk-->tape copying? (eVLBI project)

• Will limit flexibility and efficiency• Projected S2 correlator life ?

– ~ 3 years? to match eVLBI developments?

Online archive

• LBA archive ~ 650 CDs– Total content < 400 GB - one disk!– Need to “weed” recorrelations

• Online availability?– “raw” rpfits files? (weeding still needed)– Metadata required? (logs, calfiles?, corr model?)– Online as AIPS multisource fits?

• FRING, Cal files?

• Usefulness of online archive??– Worth the effort and how much?– Propose project?