Sahnow, David J. | Engineering Papers

NASA NTRS2012

ACCESS: Design and Sub-System Performance

Establishing improved spectrophotometric standards is important for a broad range of missions and is relevant to many astrophysical problems. ACCESS, "Absolute Color Calibration Experiment for Standard Stars", is a series of rocket-borne sub-orbital missions and ground-based experiments designed to enable improvements in the precision of the astrophysical flux scale through the transfer of absolute laboratory detector standards from the National Institute of Standards and Technology (NIST) to a network of stellar standards with a calibration accuracy of 1% and a spectral resolving power of 500 across the 0.35 -1.7 micrometer bandpass.

Kaiser, Mary Elizabeth↗

NASA NTRS1993

Long-slit ultraviolet spectroscopy of Comet Austin (1990 V)

The spatial distributions of the brightest features in the far-UV spectrum of Comet Austin were measured, and it is found that they are generally similar to those found for Comet Halley during two rocket observations in 1986. As in Halley, the CO profile can be fit to a radial outflow profile for a source whose size is smaller than the instrumental spatial resolution. Neither the shape nor the magnitude of the extended atomic carbon profiles, however, can be satisfactorily explained by the photodissociation of CO. No evidence is found for an extended source of CO in the coma; thus, suggestions that the additional carbon can come directly from grains are difficult to accept since Austin is a low-dust comet. The presence of the O I 1356 A feature implies that there is a photoelectron excitation source in the coma. The measured O I 1304 A distribution is consistent with H2O being the dominant source of oxygen in the coma. The atomic sulfur profile matches that expected for a daughter product of relatively short-lived parents.

Sahnow, David J.↗