The Burst and Transient Source Experiment Earth Occultation Technique

An Earth orbiting detector sensitive to gamma ray photons will see step-like occultation features in its counting rate when a gamma ray point source crosses the Earth's limb. This is due to the change in atmospheric attenuation of the gamma rays along the line of sight. In an uncollimated detector, these occultation features can be used to locate and monitor astrophysical sources provided their signals can be individually separated from the detector background. We show that the Earth occultation technique applied to the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (CGRO) is a viable and flexible all-sky monitor in the low energy gamma ray and hard X-ray energy range (20 keV - 1 MeV). The method is an alternative to more sophisticated photon imaging devices for astronomy, and can serve well as a cost-effective science capability for monitoring the high energy sky. Here we describe the Earth occultation technique for locating new sources and for measuring source intensity and spectra without the use of complex background models. Examples of transform imaging, step searches, spectra, and light curves are presented. Systematic uncertainties due to source confusion, detector response, and contamination from rapid background fluctuations are discussed and analyzed for their effect on intensity measurements. A sky location-dependent average systematic error is derived as a function of galactic coordinates. The sensitivity of the technique is derived as a function of incident photon energy and also as a function of angle between the source and the normal to the detector entrance window. Occultations of the Crab Nebula by the Moon are used to calibrate Earth occultation flux measurements independent of possible atmospheric scattering effects.Comment: 39 pages, 24 figures. Accepted for publication in the Astrophysical Journal Supplement

Tunable far infrared studies of molecular parameters in support of stratospheric measurements

Lab studies were made in support of far infrared spectroscopy of the stratosphere using the Tunable Far InfraRed (TuFIR) method of ultrahigh resolution spectroscopy and, more recently, spectroscopic and retrieval calculations performed in support of satellite-based atmospheric measurement programs: the Global Ozone Monitoring Experiment (GOME), and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY)

About the measurements of the hard X-ray background

We analyze uncertainties in the cosmic X-ray background measurements performed by the INTEGRAL observatory. We find that the most important effect limiting the accuracy of the measurements is related to the intrinsic background variation in detectors. Taking into account all of the uncertainties arising during the measurements we conclude that the X-ray background intensity obtained in the INTEGRAL observations is compatible with the historic X-ray background observations performed by the HEAO-1 satellite.Comment: 20 pages, 4 figures, accepted for publication in Astrophysics and Space Scienc

Report of the Terrestrial Bodies Science Working Group. Volume 7: The Galilean satellites

The formational and evolutionary history of natural satellites, their mineralogical composition and other phenomena of scientific interest are discussed. Key scientific questions about IO, Ganymede, Callisto, and Europa are posed and the measurements and instruments required for a Galilean satellite lander in the 1980's are described

Venus/Mercury swingby with Venus capsule. Preliminary science objectives and experiments for use in advanced mission studies

Venus/Mercury swingby with Venus capsule - preliminary science objectives and experiments for use in advanced mission studie

Scientific applications of radio and radar tracking in the space program Conference proceedings

Radar and radio tracking applications in space progra

Observation requirements for unmanned planetary missions, part 2

Observation requirements for unmanned planetary mission

Retrieval and molecule sensitivity studies for the global ozone monitoring experiment and the scanning imaging absorption spectrometer for atmospheric chartography

The Global Ozone Monitoring Experiment (GOME) and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) are diode based spectrometers that will make atmospheric constituent and aerosol measurements from European satellite platforms beginning in the mid 1990's. GOME measures the atmosphere in the UV and visible in nadir scanning, while SCIAMACHY performs a combination of nadir, limb, and occultation measurements in the UV, visible, and infrared. A summary is presented of the sensitivity studies that were performed for SCIAMACHY measurements. As the GOME measurement capability is a subset of the SCIAMACHY measurement capability, the nadir, UV, and visible portion of the studies is shown to apply to GOME as well