<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Well, the "offset" is back. UVFIX was run on all the data before it was DBCON.<div><br></div><div>This offset was not seen after UVFIX for one day of the 2006 A-array data but I did not check all days.</div><div><br></div><div>--Glenn<br><div><br><html>Begin forwarded message:</html><br class="Apple-interchange-newline"><blockquote type="cite"><div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><b>From: </b></font><font face="Helvetica" size="3" style="font: 12.0px Helvetica">Mark Dickinson <<a href="mailto:med@noao.edu">med@noao.edu</a>></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><b>Date: </b></font><font face="Helvetica" size="3" style="font: 12.0px Helvetica">April 2, 2008 11:15:29 AM HST</font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><b>To: </b></font><font face="Helvetica" size="3" style="font: 12.0px Helvetica">Glenn Morrison <<a href="mailto:morrison@cfht.hawaii.edu">morrison@cfht.hawaii.edu</a>></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><b>Cc: </b></font><font face="Helvetica" size="3" style="font: 12.0px Helvetica">Mark Dickinson <<a href="mailto:med@noao.edu">med@noao.edu</a>></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><font face="Helvetica" size="3" color="#000000" style="font: 12.0px Helvetica; color: #000000"><b>Subject: </b></font><font face="Helvetica" size="3" style="font: 12.0px Helvetica"><b>you'll feel better if you delete this message</b></font></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; min-height: 14px; "><br></div> </div>Hi Glenn -<br><br>I'm finally getting back to looking at the VLA vs. other astrometry using the newest<br>catalogs that you sent me on January 16. I'm sorry to say that if I compare these new<br>radio positions to the old Richards 2000 positions or the Biggs & Ivison 2006 catalog<br>(from the same data as Richards 2000), I'm still seeing evidence for systematic<br>astrometric offsets with a pattern that looks very much like it did before you did all<br>of the work to rereduce the data. I'm very surprised by this because I really thought<br>you had fixed this & checked the results - but somehow the pattern still seems to be there!<br><br>See the attached plots. The first one (vlagm08_ab06) compares your new positions<br>(from the January 16 catalog) to the Biggs & Ivison 2006 catalog. The second plot<br>comes from July 31 2007 and shows the old ABCD-array reduction (before you<br>had rereduced the data) compared to B&I'06. You'll see that they look very similar.<br>I think the new residuals are slightly smaller than the old ones, but overall the same<br>systematic pattern is visible. Comparing to Richards 2000 instead shows the same thing.<br><br>I could *swear* that you showed me plots that indicated you had fixed the<br>rotation/offset problem - so do you know how it could have crept back in again?<br><br><span class="Apple-tab-span" style="white-space:pre"> </span>Mark<br><br></blockquote></div></div></body></html>