From lincoln@rglinux2.cfa.harvard.edu Wed Jan 22 07:04 MST 2003 Date: Wed, 22 Jan 2003 09:04:37 -0500 (EST) From: Lincoln Greenhill To: analysts@cv3.cv.nrao.edu, cc: paul kondratko Subject: BG132 MIME-Version: 1.0 X-MailScanner: Found to be clean X-MailScanner-SpamCheck: not spam, SpamAssassin (score=0, required 7, DEAR_SOMEBODY, SIGNATURE_LONG_SPARSE, SPAM_PHRASE_00_01, USER_AGENT_PINE) X-Lines: 36 Status: RO Dear Analysts As a result of BG132 being executed when 9 recently moved antennas of Y27 had position errors >> 1 lambda, we estimate that the sensitivity of the VLA will be equivalent to a 12 antenna array. This is a serious loss. As a user, I suggest strongly that the VLBA be more attentive to this specific aspect of VLA configuration and operation for projects that use the phased array. Had our observing strategy been the same as the one originally proposed, the loss would have been catastrophic. We luckily changed to external phase referencing shortly before the run. As a result, the data is probably still worth correlating. When done, please send the tapes to me. (The current cornotes indicate Paul Kondratko.) We will let you and Barry know whether we need to reobserve after we study the data. Regards, Lincoln -- Lincoln J. Greenhill Smithsonian Astrophysical Observatory Harvard-Smithsonian Center for Astrophysics 60 Garden St, Cambridge, MA 02138 Telephone: 1 617-495-7194 FAX: 1 617-495-7345