From Brian.R.Dennis.1@gsfc.nasa.gov Fri Mar 1 09:48:49 2002 Received: from sunspot.ssl.Berkeley.edu (sunspot.ssl.berkeley.edu [128.32.147.25]) by ssl.berkeley.edu (8.9.3+Sun/8.9.3) with ESMTP id JAA18484 for ; Fri, 1 Mar 2002 09:48:48 -0800 (PST) Received: from achamp.gsfc.nasa.gov (achamp.gsfc.nasa.gov [128.183.172.208]) by sunspot.ssl.Berkeley.edu (8.9.3+Sun/8.9.2) with SMTP id JAA09703 for ; Fri, 1 Mar 2002 09:48:47 -0800 (PST) Received: from maclap ([128.32.98.225]) by achamp.gsfc.nasa.gov with SMTP for hhudson@ssl.berkeley.edu; Fri, 1 Mar 2002 12:48:45 -0500 From: "Brian R. Dennis" To: "Hugh S. Hudson \(SSL\)" Subject: Text Version of Tohban Report Date: Fri, 1 Mar 2002 12:48:51 -0500 Message-ID: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="----=_NextPart_000_0010_01C1C11F.707EF540" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.2416 (9.0.2911.0) Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4807.1700 Content-Length: 9277 Status: R This is a multi-part message in MIME format. ------=_NextPart_000_0010_01C1C11F.707EF540 Content-Type: multipart/alternative; boundary="----=_NextPart_001_0011_01C1C11F.707EF540" ------=_NextPart_001_0011_01C1C11F.707EF540 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit ------=_NextPart_001_0011_01C1C11F.707EF540 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

------=_NextPart_001_0011_01C1C11F.707EF540-- ------=_NextPart_000_0010_01C1C11F.707EF540 Content-Type: text/plain; name="Tohban Status Report.txt" Content-Transfer-Encoding: quoted-printable Content-Disposition: attachment; filename="Tohban Status Report.txt" Tohban Status Report=20 Prepared by Brian Dennis Covering period from Saturday, February 23 through Friday, March 1, 2002 = (DOY 54 - 60) Tohban Responsibilities General Review HESSI's overall performance from a scientific perspective. Relate HESSI's performance to the current state of solar activity Coordinating with external observing programs via Dick Canfield. Inform operations and science personnel of any major solar events or = possible instrumental anomalies. Specific Get contact schedule listing from hessiops/timeline/Contact_Schedule.txt Keep track of solar activity by monitoring GOES plots and Max Millennium = emails. Keep track of spacecraft and instrument status by being at the MOC for = Berkeley and/or Wallops passes. Keep log of all major events that could affect the scientific return = from the mission. Useful information HESSI Data Center Web site: = http://hesperia.gsfc.nasa.gov/hessidatacenter/instrument.html HESSI Eclipse and SAA times: = http://hessi.ssl.berkeley.edu/cgi-bin/soc/index.pl/saa_ecl.pl Or ftp://hessi.ssl.berkeley.edu/pub/saa_ecl/hessi_observation_times Max Millennium contact: Dick Canfield canfield@physics.montana.edu (406) = 994-5581 SOHO Contact: Stein Vidar Hagfors Haugan ESA SOHO SOC = (shaugan@esa.nascom.nasa.gov) Office phone: 301-286-9028, cell phone: 240-354-6066, home phone: = 410-997-8102 <100 character messages to 2403546066@messaging.sprintpcs.com SOHO JOP153 Major Flare Watch/MMOP003 Region Likely to Produce Major = Flares CDS/EIT/LASCO/SUMER/MDI/UVCS/TRACE/HESSI/MaxMillennium TRACE Contact: Jake Wolfson wolfson@sag.lmsal.com office: (650)424-4032, = home: (408)253-0238 Overview Sun active with several M flares already detected and filling the = onboard Solid State Recorder (SSR). Now have up to 6 Berkeley passes, 6 Wallops passes, and 3 Waldheim = passes per day. Can dump up to ~5.1% of SSR per pass, i.e. potentially up to 60% per = day. Typically, we get <3% input to the memory on a normal orbit with the Sun = quiet. Detector #8 has high noise levels when the aft antenna is on. This = typically happens for half of each pass and is because of the closeness = of this antenna to detector 8. There is a 5-s gap in data transmission = on switching from one antenna to the other. Battery pressure difference between cells is still in the red zone at = ~300 kPa. It will likely stay this way until it is discharged more = deeply than it is now but this is not likely to happen in normal = operation. Nobody seems too worried about it. Saturday, February 23 Pass at 10:05 EST Memory 27.8% full at start of pass - reduced to 22% at end, i.e. 5.8% = dumped on this pass. Cryocooler operating at 50 watts. Accelerometer readings 12 - 17 mG Coldplate temperature: 71.8 K, shield: 150. 3K All detectors at normal rates. Pass at 11:48 EST Thin attenuator moved out at 19:49:12 UT Spin rate 13.83 rpm Pass at 13:30 EST Thin attenuator moved back in at 21:32:21 UT Only 2.1% of memory filled on orbit with thin attenuator out. Fraction of SSR filled decreased from 7.8% to 6.3% with data dump on = this pass. Pass at 15:11:59 EST 2.3% put into SSR since previous pass. Decreased from 8.2% to 3.1% = during pass. Sunday, February 24 Pass at 10:13 EST 6.2% of SSR filled on last pass compared to the normal 2 - 3%. Detector 2 was very noisy with all rates in the red zone. Turned high = voltage to detector 2 off. Ramped detector 2 voltage back up to level 178 to achieve segmentation. = Detector still noisy so turned high voltage off on the immediately = following Wallops pass. Shield temperature was down to 149.7 - 150.0. Ran timed commands to = cycle heater on for 10-minute cycles to increase shield temperature. Pass at 11:56 EST Detector 2 HV ramped up to level 10 (171.6 v), 100 (1936 v), 130 (2524.5 = v), 150 (2916 v -segmentation), in sequence. Detector 2 became noisy as soon as the segmentation voltage was = achieved. HV turned off before end of pass. Pass at 13:38 EST Ramped detector 2 HV up to level 130 (presegmentation), 150 = (segmentation), then back down to 130 after it became noisy again. All detector-2 threshold levels raised to maximum levels t reduce noise = at presegmentation level. Lowered threshold level to 150, 75, then = backup to 150 to reduce noise counts. This corresponds roughly to about = 30 keV. Pass at 15:20:20 EST Turned of HV to detector 2 at 55:23:25:00 UT Monday, February 25, 2002 Pass at 08:39:48 EST Ramped detector-2 HV up to 130 and then 150. Still giving noisy data. = Ramped voltage back down to 0. Rates somewhat high in rear segments on immediately following Wallops = pass but probably because the geomagnetic latitude was high for this = part of the orbit. Pass at 10:21:35 EST Detector 2 HV off. All other detectors show normal rates. Tuesday, February 26, 2002 Pass at 08:48 EST Test of thin and thick shutter movement conducted timed at the nutation = period of 73 s. 16:50:50 UT Thick in 16:52:20 UT Thin out 16:53:50 UT Thick out 16:54:49 UT Thin in 16:58:00 UT Thin out Temperature of shield had fallen to 149.8 K even though the heater has = been cycled on. Pass at 10:29:44 EST 4.3% of SSR added on previous pass with both attenuators out. Detector 2 HV brought up to level 130 (presegmentation level), then to = level 150 (segmenation). Rates still high. HV ramped down to level 130. Tried to power off rear FET but wrong bit = was changed in the IDPU. Wednesday, February 27, 2002 Spectrum Astro people here to raises spin rate to 15 rpm and balance the = spacecraft by adjusting the solar panels. Pass at 08:55 EST Spin rate already up to 15 rpm. Thin shutter was left in overnight. Detector 2 operating at the presegmentation voltage (level 130) has a = resolution of ~10 keV and a threshold of ~25 keV. Pass at 10:37 EST Detector 2 HV increased to level 150. Turned off thte rear CSA but still = getting high rate from the front segment. Returned HV to level 130. Coldplate temperature indicated 73.2 K but was now using only 8 bits = instead o f the usual 16 because of the ACS tests. Thursday, February 28, 2002 Pass at 9:03 EST Experimented with Detector #2 HV. Varied as follows: level 130 - 135 - = 136 - 137 - 134 to test noise level near segmentation. Coning circle ~0.2 degrees in diameter. Spin rate 15.037 rpm. Pass at 10:45 UT SAS indicating "near limit" even though coning circle is small and = centered on SAS axis Friday, March 1, 2002=20 Pass at 09:14 EST =20 ------=_NextPart_000_0010_01C1C11F.707EF540--