Assigned ID: 127 ----- Attempting Submission 1 (Thu Mar 06 10:00:31 GMT 2008) ----- Submission failed communicating with the submission server: java.rmi.ServerException: RemoteException occurred in server thread; nested exception is: java.rmi.RemoteException: File Transfer Failed On Server: java.lang.NullPointerException ----- Attempting Submission 2 (Thu Mar 06 10:03:26 GMT 2008) ----- Phase I Proposal 127 (leo1ar-17.apt) successfully submitted. ----- Attempting Submission 3 (Thu Mar 06 22:39:46 GMT 2008) ----- Phase I Proposal 127 (leo1ar-17.apt) successfully submitted. ----- Attempting Submission 4 (Thu Mar 06 23:51:17 GMT 2008) ----- Constraining the mass of the Galaxy at large radii remains a difficult problem. Available data are still rather scarce, and orbits of even a few objects at large radii can have a large impact. We propose to obtain proper motions for the Galaxy's two most remote satellites, Leo I and Leo II, which orbit the Galaxy at about 200 kpc. Together with the radial velocities of these galaxies, which are well known, the proper motions allow space velocities to be consructed: these can remove signifiicant uncertainty in the Galactic mass models, and in particular settle the vexed question of whether or not Leo I is gravitationally bound to the Galaxy. The proper motion of Leo I as derived from archival ACS and WFPC2 data is addressed in this proposal, while a companion (approved Cycle 16) WFPC2 imaging proposal addresses the orbit of Leo II.

RESOLVED STELLAR POPULATIONS 12 58900.00 false 0.0 0.0 false false false false false SUPPORTED 11 13 30.4400 +22 09 52.20 J2000 WFPC2 Imaging No F606W WFPC2 Imaging No F814W