Posts Tagged From Shawn

Preparing for NASA’s LCROSS mission

During Monday’s (3/2/9) engineering night Shawn Callahan, Morag Hastie, Tim Pickering, Phil Hinz, and Ale Milone tested the f/15 AO system capabilities to develop procedures to image lunar impact craters for the upcoming NASA LCROSS mission. To learn more about this interesting NASA mission go to:

On this mostly clear evening, the moon’s illumination was less than 50% causing polar LCROSS impact craters to be unlit. We used JPL’s HORIZONS software and scripts from Tom Trebisky to generate ephemerides for the moon. As soon as we began non-sidereal tracking the center of the moon we offset to the cusp at the northern intersection of the bright limb with the terminator. This region of the moon has several mountains and crater walls in the dark limb tall enough to catch the first rays of sunrise.

The AO system was able to lock onto one glowing oblong shaped mountain top. We were all treated to see amazing lunar images free of most atmospheric distortions while looking through 2.7 airmass (22 degrees elevation angle). This was a first for the MMT!

We tried locking onto various other moonscapes with less contrast but were unsuccessful before the rapidly setting moon prevented further observations. Regrettably our efforts did not leave enough time to capture these beautiful images of the moon with the AO system locked. (Next time!) Further testing is required to determine if we can lock the AO system on the candidate craters.

The LCROSS craters shall be illuminated during our next engineering run in early April. During this run we plan to use the f/9 and/or f/5 telescope configuration to test and verify our procedures for locating and tracking each candidate impact site.

The LCROSS mission is scheduled to impact August 28th at 4:39 UTC (21:39 MST). On this evening, sunset at the MMT is 18:52, and the moon sets at 00:27. The moon shall be at an elevation angle of 42 degrees (1.5 airmass) during impact.


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