LCROSS Mission Impact Observation

10.09.2009

The impact of the LCROSS payload into the Lunar crater Cabeus was observed from the Via Capote Observatory.  Local conditions were generally good with high humidity and calm winds.  Seeing conditions were “good” to “very good”.  

 

 The observations were made through a Meade 14” SCT featuring an f/10 focal ratio.  The telescope mount is an LX200 tracking in “Lunar” mode.  Focus was maintained using an Optec temperature compensated focusing system. A computerized focus run was preformed approximately 8 hours prior to predicted impact using a background star.

Image data was collected using a Santa Barbara Instruments ST-402 camera, cooled to     -5 C.  The image data was collected “un-binned”. This configuration yielded an image scale of approximately .5 arc seconds per pixel and a total field of view of approximately 7 X 4 arc minutes.  To accommodate the very bright background of the lunar disk, three filters (blue, green, and yellow) were stacked and inserted into the optical path of the camera so as to prevent saturation.  The camera was set to acquire data continuously with .1 second integration periods.  All images were dark frame corrected.  No flat field frame corrections were required or applied.  No other signal processing was applied.

The observatory clock was synchronized to NIST approximately 8 hours prior to predicted impact. Data was acquired from 13 seconds prior to predicted impact until 739 seconds after impact.  652 individual images were acquired during the period spanning the predicted impact.

There was no obvious indication of impact from the data collected.  Frame to frame variation induced by seeing and variable transparency conditions produced some notable candidates for suspected impact but closer examination of the data discounted the possibility of these being anything other then artifacts of the variable conditions.  Attached are a few sample images, post and pre impact with the target area highlighted in the first image.

 

         

Image Time 6 seconds before predicted impact

Image Time 633 seconds after predicted impact