UVCS MISSION LOG
				----------------

	Date:		22 April 2004
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 	Last revision:	23 April 2004 (Wu)
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	File Name: 	2004.04.22.a.log
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	Compiled by:	R. Wu
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	UVCS Activity:	UVCS in Safe Mode Due to SOHO ESR
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	SOHO Activity:	
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	EOF Staff:	M. Uzzo: Lead Scientist
	----------	Y.-K. Ko: Commander
			M. Uzzo: Planner
			R. Wu

	Command file:	No Commanding

	Activity:
	---------

	1) UVCS in Safe Mode Due to SOHO ESR

	Sequence: 

	SCI_SPEC: SOHO back in ESR at approximately 16:12 UT
	
		  UVCS Aperture Door is closed, and Detector Power is turned
		  off.  UVCS TSU Substitution Heater (Circuit #84) still on.

		  The ESR is believed to have been triggered by the FSPAAD 
		  (Fine Sun Pointing Attitude Anomaly Detector).  It is 
		  currently theorized that the comparator has degraded and
		  become unreliable due to aging.

		  From email received from SOC Thu, 22 Apr 2004 22:59:34 (UT):

		  SOHO is still in ESR mode, with wheels spun up and no ongoing 
		  thruster firings. This is a stable configuration that 
		  requires little maintenance.  The roll rate is (near) zero, 
		  but the roll angle is not known. The pointing (pitch and yaw)
		  is evolving slowly. We have currently gone back to low rate 
		  telemetry to enable locking on 26m stations. If 26m stations
		  cannot lock to give us near-continuous low rate, we will 
		  request a 34m station while the spacecraft emergency is in 
		  effect.  SOHO will be left in this configuration over the 
		  night. No 34m stations are scheduled for tomorrow.

	OBS_PROG: 

	SCI_OBJ:  

	OBJ:      

	CMP_NAME: 

	CMP_NUM:  

	Duration: start: 2004.04.22.16:12
                    end: 2004.04.23.16:00

	ONUMs =	21147

	Instrument configuration:

		- Pointing:  Sun center

		- Spacecraft Roll:  0 Degrees

		- Roll: 262 Degrees (922) 
 
		- Mirror/Occulter:  5.0 Ro
                                    1.5 mm overocculting

		- LYA Slit:    50 um
		- OVI Slit:   150 um 

		- LYA GRTPOS: 128000
		- OVI GRTPOS: 188310

		- LYA HIGH VOLTAGE POWERED OFF
		- OVI HIGH VOLTAGE POWERED OFF
		- VLD HIGH VOLTAGE POWERED OFF

		- LYA DETECTOR POWERED OFF
		- OVI DETECTOR POWERED OFF
		- VLD DETECTOR POWERED OFF

		- OVI mask:   OVI_str_188_225 in slot 5

	Fits Files:

GAP between 04/22/04|16:12:37(15987) and 04/22/04|16:24:17(16252)