Precision Pointing in the Sky for IBEX Interstellar Flow Observations - Use of the Moon With the IBEX-Lo Star Sensor
Abstract
The Interstellar Boundary Explorer (IBEX) is in Earth orbit and imaging Energetic Neutral Atoms (ENAs) from the heliospheric boundary and those that flow through the solar system from the interstellar medium. Two sensitive ENA cameras (IBEX-Hi and Lo) that point radially outward on the spinning and sun-pointing spacecraft obtain full-sky images over time periods of six months. With IBEX-Lo, we can identify species of the interstellar flow, such as He and O. Together with accurate knowledge of the flow direction, interstellar parameters and the interaction with the heliosphere can be deduced. In order to provide precision pointing information on the interstellar flow in astronomical coordinates, a star sensor is co-aligned with the IBEX-Lo. The star sensor is capable of distinguishing bright stars, superior planets, and the moon. The objects' known coordinates act as direction pointers for the satellite's position. The moon poses a unique problem because of its highly variable shape and distance from the satellite. New flight data allow us to calibrate the star sensor's signal to known parameters of moon passage. In comparison with laboratory calibrations and simulations, the moon's barycenter can be found by modeling the star sensor's response to a range of moon phases. As will be discussed, the correction can be accurately applied to the moon signal from flight data.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2009
- Bibcode:
- 2009AGUSMSH31C..02O
- Keywords:
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- 2126 Heliosphere/interstellar medium interactions;
- 6250 Moon (1221);
- 7894 Instruments and techniques