Scientific/Technical Abstract:

HIPO is a special-purpose science instrument for SOFIA that is designed to provide simultaneous high-speed time resolved imaging photometry at two optical wavelengths. It will be possible to mount HIPO and FLITECAM on the SOFIA telescope simultaneously to allow data acquisition at two optical wavelengths and one near-IR wavelength. HIPO will have a flexible optical system and numerous readout modes, allowing many specialized observations to be made. The instrument characteristics required for our proposed scientific pursuits are closely aligned to those needed for critical tests of the completed SOFIA Observatory, and HIPO will be used heavily for these tests.

Our main scientific interest is in the use of HIPO for observing stellar occultations. In a stellar occultation, a star serves as a small probe of the atmospheric structure of a solar system object or the surface density structure of a planetary ring or comet. Such observations provide information at high spatial resolution that would otherwise require a space mission to obtain. This work makes use of SOFIA's mobility, freedom from clouds, and near-absence of scintillation noise to provide the best possible occultation data.

The low atmospheric scintillation in airborne photometry gives HIPO the potential to detect P-mode stellar oscillations in sunlike stars and will provide excellent photometry of stellar transits by extrasolar planets. HIPO will be available for Guest Investigator use on a collaborative basis, and potential Guest Investigators should contact the PI prior to proposing to insure that the proposed observations are feasible and make the best use of HIPO 's capabilities.

Optical Layout:

The HIPO optical system will be reconfigurable to meet the its varied requirements. The basic layout, with FLITECAM mounted also, will be as shown in the figure below. It incorporates two dichroic beamsplitters, one to divert the infrared beam to FLITECAM (if mounted) and one to split the red and blue sides of the HIPO optical paths. Either or both of these may be removed if desired. It will also be possible to move either CCD to the optimal SOFIA focal plane location for highest spatial resolution and throughput.

The filter wheels will be located near the pupil image formed by the collimator optics. Two positions in the red CCD's filter wheel will be used for Shack-Hartmann lenslet arrays. The filter wheels will be on stages to allow optimum positioning of a pupil mask and the lenslet array.

The region between the mounting flange and the gate valve on the telescope can be evacuated to reduce image degradation due to density fluctuations in this region of the optical path.

HIPO Performance Summary – Instrument sensitivity and resolution summary is provided to permit estimating feasibility of scientific investigations.

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All sensitivity and resolution data are preliminary, and based on anticipated performance of the observatory and the instrument.  Actual performance of the SOFIA telescope and instrument combination will be established after flight operations begin.  Telescope performance is expected to be upgraded during the first two years, and instrument performance may be upgraded, or additional modes or capabilities may be added.

Performance estimates given here are based on data supplied by the instrument team. Further details and updates may be obtained from the instrument team via the contact information given above.

Further References:

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