n21dk01

    Version as of 04:20, 29 Nov 2024

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    n21dk01 Correlation Report

    General information

    • Project: "Wideband spectral line VLBI study (Dongjin Kim) 22/43GHz 8Gbps"
    • Epochs: G, H, I, J, E, K, L
    • Station feedback:

    Status

    what date
    Effelsberg transfer Epochs G and H complete, remainder postponed due EVN Session 2 VLBI (27 May-17 Jun) 20.05.2021
    Yebes transfer Epochs G, H, I, J, E complete 11.06.2021
    Effelsberg transfer Epochs I, J, E, K, L completed 23.06.2021
    Fringes Ef-Ys K-band and Ef-Ys Q-band, epoch G 10.06.2021
    KVN started data transfer 16.06.2021
    KVN ongoing transfers... 16.08.2021 still transferring... (not complete)
    Epoch G full correlation K+Q v1 finished 15.08.2021
    Epoch I full correlation K+Q v1 finished 16.08.2021
    Released (difxexport) version 1 of epoch G and epoch I. 17.08.2021
    Data transfer status
    Ep DOY Ef 2021 Ys Kt Ku Ky
    G 124 20.5. ok 8.6. ok 22.7. ok 10.7. ok 1.7.
    H 127 19.5. ok 29.5. ok 25.7. ok -not started- 23.7.
    I 141 20.6. ok 5.6. ok 5.8. ok 4.8. ok 3.8.
    J 141 21.6. ok  8.6. ok -not started- -not started- ongoing (13.8.)
    E 142 20.6. ok 11.6. ok 1.8. ok 29.7. ok 28.7.
    K 143 23.6. ok (not observed) -not started- -not started- -not started-
    L 143 23.6. ok (not observed) -not started- -not started- -not started-
    Production Correlation Status
    Ep DOY Correlation Config Diagnostics Notes
    G 124 15.8.2021 v1 v2d, vex Residuals pdf, FITS pclist Ef not on source until ~18:30 UT
    Ku residual rate +20 mHz
    H 127        
    I 1411 16.8.2021 v1 v2d, vex Residuals pdf, FITS pclist Ku residual rate +20 mHz
    J 141
     
         
    E 142 (pending)     Ku residual 0 Hz after Ku -0.8e-12 s/s in VEX
    K 143        
    L 143        

    A Priori

    Yebes

    • J. Gonzales: rate 1.17e-13 s/s, offsets in logs named n1k01?ys.log on vlbeer.
    • Did not observe K and L due to heavy rain and broken shutter.
    • Transferred the data of G, H, I, J, E.
    • VEX freq block sidebands UUUU UUUU LLLL LLLL rather than the default UL UL ... from SCHED
    • Epoch E: scan No0003 (142-0814) file empty or not recorded

    Effelsberg

    • U. Bach, etransferred epochs G & H. Pending transfer of the remaining epochs.
    • Offset +19.3 usec in G
    • Logs named ndk01g, ndk01h, and later n1k01i, n1k01j, n1k01k, n1k01l, n1k01e on vlbeer
    • H-maser rate same as in GMVA f211a, i.e., 2.05e-13 s/s.
    • VEX freq block sidebands UUUU LLLL rather than the default UL UL ... from SCHED.
    • Epoch G: wind and bad weather, first part ot track unusable, not on source until ~18:30 UT

    KVN Yonsei, Ulsan, Tamna

    • Table of clock offsets, sign for VEX same as in table
    • Table of most recently determined site positions
    • H-maser rates not available, assuming 0 us/s for Yonsei and Tamna, same 0 us/s for Ulsan but high residual rate 20 mHz so could perhaps use VEX Ku -0.8e-12 s/s
    • Waiting for e-transfer for remaining epochs
    • Tie of KVN to Ef+Ys : shift KVN VEX clocks by -2.83 us from kvn a priori values

    DiFX

    Special setup for correlation, because Effelsberg does not have simultaneous K and Q capability.

    • Initial attempt using v2d "freqIds=..." and a K-band and a separate Q-band v2d file was only partially successful. Issue: any change in array composition (e.g., telescope recorded data in one scan, in another one not) jumbles the DiFX .input FREQ table frequency IDs and the nominally K-band freqIds list refers to some Q-band recorded channels as well.
    • Production approach uses VEX file where Ef has been made dual K&Q, a v2d file with two Datastreams for Ef (one K, one Q), and a bit of scripting to separate the Ef filelist into two lists one with K-band and the other with Q-band VDIF files
    • Zoom bands of 64 MHz added into to KVN 2ch x 512 MHz to match Ef Ys 64 MHz wide channels in USB/LSB
    • Zoom bands added also to Ef Ys 64 MHz LSB channels in order to flip these into USB and produce all-USB visibility data; avoids HOPS fourfit issues with mixed USB-LSB visibilities

    Effelsberg file list splitting by band, example for Epoch G:

    vsum -s /data/n21dk01g/Ef/*.m5a > filelist.ef
    rm -f filelist.ef.k filelist.ef.q
    for scanNr in `vexpeek -s n21dk01g.vex.obs | grep kband | grep EF | cut -c 3-6`; do
        echo "grep kband 01g_ef_no$scanNr"
        grep "01g_ef_no$scanNr" filelist.ef >> filelist.ef.k
    done
    for scanNr in `vexpeek -s n21dk01g.vex.obs | grep qband | grep EF | cut -c 3-6`; do
        echo "grep qband 01g_ef_no$scanNr"
        grep "01g_ef_no$scanNr" filelist.ef >> filelist.ef.q
    done

    Notes

    The FITS-IDI file of each epoch contains both K and Q band, at a resolution of 0.5 seconds and 0.25 MHz/channel

    This is due to the way that the correlation had to be configured because not all scans had all recordings from all stations, hence the DiFX-internal frequency indices were not consistent across all scans, hence selective correlation in two runs using only specific frequency indices and per-band averaging settings never produced consistent K(/Q)-only products per run.

    The K and Q bands must be manually split out by the PI from the FITS-IDI file under AIPS/CASA.

    For K-band, temporal averaging needs to be applied during the manual splitting to get from 0.5s AP to PI-requested 1.0s APs.

    For Q-band, spectral averaging needs to be applied during the manual splitting to get from 0.25 MHz/channel to the PI-requested 0.50 MHz/channel.

    Post-Correlation checks

    Residuals

    FITS completeness (pclist)