From - Thu May 24 12:19:31 2001 Return-Path: Received: from cfa.harvard.edu (cfa [131.142.10.1]) by cfauvcs0.harvard.edu (8.9.2/8.9.2/cfunix S 0.5) with ESMTP id MAA26545 for ; Thu, 24 May 2001 12:06:46 -0400 (EDT) Received: from cfauvcs4.harvard.edu (cfauvcs4 [131.142.24.163]) by cfa.harvard.edu (8.9.2/8.9.2/cfunix M-S 0.1) with ESMTP id MAA13025 for ; Thu, 24 May 2001 12:06:46 -0400 (EDT) Received: from localhost by cfauvcs4.harvard.edu (8.9.2/8.9.2/cfunix S 0.5) with ESMTP id MAA26039 for ; Thu, 24 May 2001 12:06:45 -0400 (EDT) X-Authentication-Warning: cfauvcs4.harvard.edu: dhphilli owned process doing -bs Date: Thu, 24 May 2001 12:06:45 -0400 (EDT) From: Dan Phillips X-Sender: dhphilli@cfauvcs4.harvard.edu Reply-To: dhphillips@cfa.harvard.edu To: Raid Suleiman Subject: mirror calibration text: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Content-Length: 1187 X-Mozilla-Status: 8001 X-Mozilla-Status2: 00000000 Flight calibration of the mirror-pointing mechanism using known star positions has revealed a difference from the pre-flight mirror calibration used in previous versions of the DAS. DAS 33 uses this new calibration in the MIRANGL variable, which refers to the height above the sun center of a fictitious point between the two UVCS slits. The flight calibration is only valid down to 1.74 Rsun. For observations below this height, DAS 33 shows '******' for MIRANGL, as well as for INS_YR and other display values that rely on MIRANGL. Because of the current lack of a new calibration below 1.74 Rsun, and because individual observations since the start of the mission have been labeled with a consistent "commanded" value for the UVCS mirror angle, DAS 33 retains the old mirror calibration in the new variable "CMDMIR". The user should recognize that this value is no longer the most accurate calibrated value for the mirror angle. In addition, the DAS is not as yet able to perform a correction for the "crosstalk" between UVCS mirror and grating mechanisms. Users needing precise UVCS pointing calculations need to correct the DAS pointing information for this effect.