Observation / Project Log

What happened, and when

A curated, factual record of the project's milestones. Entries summarise documented project records. Where a milestone is known only indirectly, the entry says so.

  • Observation
  • Processing milestone
  • Calibration milestone
  • Software milestone
  • Scientific result

  1. Scientific result Fixed transit telescope published

    The fixed, zenith-pointing 5 m educational telescope and its replication at Saudi universities are published in IEEE Antennas and Propagation Magazine. Publication

  2. Observation DISH222 survey observing begins

    A series of Galactic survey sessions with the steerable DISH222 runs from 13 to 26 August. Only the 26 August session is in the research archive.

  3. Processing milestone Session-based bandpass flattening

    A strong slope across the receiver band had caused most wide spectra (75–91%) to be rejected as corrupted. Measuring the slope from each session and removing it recovered them.

  4. Calibration milestone Pointing error found and corrected

    Two sessions showed pointing errors of 5–10°, visibly displacing the Galactic plane. A Sun-based pointing calibration on 25 August reduced the error from 9.1° to about 1.1°.

  5. Observation Outer-Galaxy raster

    An automated raster over Galactic longitudes 146°–226° records 776 averaged spectra at 313 positions. It is today's recommended starting dataset.

  6. Calibration milestone LAB-anchored effective scale (C1)

    Relative dB values are converted to kelvin with a single effective system temperature of 330–480 K, anchored on the LAB survey. Epoch C1

  7. Scientific result First systematic comparison with LAB

    On the relative scale, the outer-arm brightness structure follows LAB (correlation about 0.8), and the velocity–longitude pattern matches closely (r = 0.96), with the anticentre located within about 1°. The peak-velocity metric compresses the rotation amplitude by about a factor of four. Validation note

  8. Processing milestone First FITS cube and maps

    The 26 August session is delivered as a spectral cube, peak and velocity maps and a catalogue in FITS format, on the relative dB scale.

  9. Observation Session used in the all-sky composite

    Known from the composite's session labels; its data are not in the research archive.

  10. Observation Galactic-plane scan and first kelvin map

    A scan around the inner Galactic plane. It was later re-derived in kelvin using the C2 calibration established on 2 Sep, becoming the first kelvin map. This is a historical product, not on the current C4 scale. Its comparison with LAB gives the efficiency of 0.30 used in C2. The native data are not in the archive.

  11. Calibration milestone Y-factor system temperature (C2)

    A warm wall compared with the zenith sky gives a Y-factor of 4.40 dB and a system temperature of 179.5 K. Combined with η = 0.30, this becomes the C2 scale used for the early September products. Epoch C2

  12. Software milestone Calibration and pointing tools in the observing software

    The observing software gains a built-in Y-factor calibration, an efficiency setting for converting antenna to brightness temperature, an automatic Sun cross-scan pointing check, and a fix that keeps each scan's pointing manifest next to its spectra.

  13. Observation Galactic-centre area scan

    An area scan of the Galactic-centre region yields a cube and maps on the C2 scale. The velocity field looks reasonable, but brightness comes out about 1.6 times LAB and does not fall off away from the plane, a discrepancy later addressed by the calibration work.

  14. Observation Anticentre-side scans

    Morning scans on the anticentre side, plus a later session, feed the all-sky composite. Only products of the morning scans are in the archive, and they are dominated by artefacts.

  15. Processing milestone All-sky "TRUSTED" composite

    Six sessions are combined, and a selection rule keeps only values between 40 and 160 K with velocities within ±35 km/s. A showcase product with incomplete native lineage. Details

  16. Observation Further area scans

    Project records indicate sessions in the Cygnus region (8 Sep) and a northern area scan (13 Sep), still on the C2 scale. Their data are not in the research archive.

  17. Calibration milestone Hot-load system temperature (C3)

    A concrete wall filling the beam gives a Y-factor of 1.29 dB and a system temperature of 895.4 K, still converted with the legacy η = 0.30. A solar transit on the same day gives an aperture efficiency of 0.582. Epoch C3

  18. Observation Galactic-centre survey (392 spectra)

    Later used for an independent archival check of the calibration pedestal. Not in the research archive.

  19. Calibration milestone Sky-referenced calibration adopted (C4)

    Eight positions of known LAB brightness give G = 1454 K and an additive pedestal p = 0.0174. The implied efficiency of 0.616 agrees with the solar measurement. A repeat hot-load attempt that day was rejected because the load covered only about a tenth of the beam. C4 is the current reference; earlier products keep their original scales. Epoch C4

  20. Software milestone Calibration checks built into observing

    New observing-software builds add a pointing check against LAB, a continuous calibration check at the current pointing, a whole-run fit of G and p, and a beam-coverage test for hot-load measurements.

  21. Processing milestone Scientific provenance record

    Instruments, calibration epochs and datasets are catalogued in a machine-readable registry. That registry drives the Telescopes, Data Library and Calibration pages of this portal.