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Session 9 - SOFIA and IR Instrumentation.
Display session, Wednesday, January 07
Exhibit Hall,

[9.07] HOPI - A High-speed Occultation Photometer and Imager for SOFIA

E. W. Dunham (Lowell Obs.), J. L. Elliot (MIT), H. B. Hammel (MIT)

Earth-based observations of stellar occultations provide extremely high spatial resolution for bodies in the outer solar system--about 10,000 times better than that of traditional imaging observations. Airborne occultation observations are particularly effective, since the controlled mobility of the observing platform allows the observer to fly within the optimum part of the occultation shadow for most events that are visible from Earth. Airborne observations are carried out above any clouds and are nearly free of scintillation noise from the Earth's atmosphere.

The combination of HOPI's high performance and the SOFIA telescope's large aperture will revolutionize the capability of the occultation technique by increasing the occultation S/N ratio and allowing observation of the more numberous events involving fainter stars. HOPI is an optical instrument (the successor to our KAO instrument, SNAPSHOT; Dunham et al. 1985, PASP 97, 1196), but we plan to allow for simultaneous, time synchronized observations to be carried out with an InSb camera, greatly enriching the results that we can obtain from certain occultations.

HOPI's characteristics also make it an ideal instrument for evaluation of the SOFIA telescope's performance. In addition, it may prove useful for observations of lunar occultations of astrophysically interesting objects and for asteroseismological observations.

HOPI Specifications

SOFIA Instrument Type: Special Purpose Science Instrument Detector Type: Two EEV CCD47-20 1Kx2K frame transfer silicon CCDs Wavelength Range: 0.3-1.1 microns in two channels Resolution/Pass Bands: Determined by filters Optical System: 6.4:1 reduction with Shack-Hartmann capability Field of View: 5.7 arcmin square Pixel size: 1/3 arcsec, unbinned. Read Noise: 3-6 electrons, depending on read speed Maximum Read Speed: 2 Mpixel/sec for each CCD Maximum Frame Rate: 20 msec for 3 80" square subframes on each CCD

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