An Estimate of the Integrated Magnitude of the LCROSS Impact Ejecta Dust Curtain for Exposure Calibration Practice (Abstract)

Volume 37 number 2 (2009)

Kurt A. Fisher

Abstract

(Abstract only) The LCROSS-EDUS (Lunar CRater Observation ans Sensing Satellite-Earth departure upper stage) lunar impact will generate a dust ejecta curtain about 10 km × 5 km high according to the NASA-LCROSS Team current best estimate impact model (CBEIM). The dust ejecta curtain could reach 20 km × 20 km. The LCROSS Team has not issued a curtain magnitude estimate for use by amateur imagers. For the limited purpose of pre-event exposure calibration practice, a rough first-order estimate of the LCROSS impact dust ejecta curtain is between 0.3 to 3.5 integrated magnitudes or 5.5 to 6.4 mpsas. This apparent brightness provides a favorable contract index against typical Earthshine (dark limb) irradiance between 12 to 17 mpsas for the dark limb (mean value 15.44 mpsas) but not against Moonshine (bright limb) at 4 to 6 mpsas.