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GREAT Early Results

In early April, GREAT successfully operated on SOFIA during three flights and a setup flight, achieving significant advancements in its performance. The instrument featured improved bandwidth of 1.5 GHz and better noise temperature, despite some limitations. Observations of Saturn and Galactic PDRs confirmed bore sight offsets and various observing modes, enabling the completion of 7-8 science projects. Looking ahead, further integration of a few projects is planned for July. Main findings will be published in an upcoming special volume of A&A, detailing the technical contributions and data processing improvements.

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GREAT Early Results

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  1. GREAT Early Results Göran Sandell, on behalf of the GREAT Consortium

  2. GREAT installed on SOFIA

  3. SHORT SCIENCE 2 (SS2) • 3 flights in early April + one setup flight (OCF4) • GREAT SS2 configuration: • L#1 1.27 – 1.39 THz (a), 1.43 – 1.52 THz (b) • L#2 1.82 – 1.92 THz • Improved Bandwidth – now 1.5 GHz • Better noise temperature

  4. Noise performance & bandwidth • SSB-noise performance vs. LO frequency • gaps are due to LO power limitations • lower performance between 1840 and 1885 GHz is due to LO noise contributions • clean overall band-pass (right hand side) • usable bandwidth up to 1.5GHz

  5. Performance Summary

  6. GREAT Short Science • oneobservatorycharacterizationflight hardware & procedures (preparedduringlineops & in HIL/SIL) worked fine, butoperationtroubledbyserioussoftwareissues finally, on Saturn & galacticPDRs, wedetermined & verified: • boresightoffsets GREAT to FPI • Z-focusoffset GREAT to FPI • GREAT observingmodes • pointed, raster, on-the-fly, in total power and choppedobservingmodes • in both, continuum and spectrospopymodes message: a single commissioning flight for an instrument with the complexity of GREAT (blind from ground) is sub-critical. • threeshortscienceflights

  7. GREAT Short Science sciencedemonstration was amazinglysuccessful • duringourthree SS2 flights • 7-8 scienceprojectscompleted (to theextentpossible) • 2-3 projects do needmoreintegration time, will bere-scheduled in July • science will bepublished in A&A specialvolume in autumn, withtechnicalcontributionsdesribing GREAT • status of dataprocessing • calibrationpipeline (atmosphericmodels) moredemandingthanexpected [lack of calibratedwaterreadingsfromonboardmonitorpainful] • improving on shortcomings (headerinformation, timing)

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