SOHO Daily Meeting Notes Meeting chaired by Laura Allen 20 July 1996 (DOY 202) Notes by Julia Saba/MDI --------------------------------------------------------------------------- Announcements: None ------------- FOT Report (by Bret Snapper): ---------- o Spacecraft nominal o Anomalies: 1 DMA failure at DOY 201/2249 A packet was lost during heavy commanding. o Activities done: Roll Steering Law, one VIRGO, two CELIAS loads o Activities planned: Roll Steering Law, and VIRGO and SWAN loads o Ground System Anomalies: - 201/1428 TGC problem at D27 (again) caused 40 sec TLM loss, unrecoverable. This has been happening for the last few days and is being looked into. - 201/1511 String 1 crash caused 8 min loss of NRT commanding time. - 201/2205 TLM dropout from D42 during station handover. TLM was being received from D27 while PACOR had D42 as prime. Data lost at EOF for period 2205-2213. (Data recoverable.) - 202/0651 Recoverable 2 min TLM outage from TCA failure at D61. - 202/0809 Unrecoverable 16 min TLM outage from TGC failure at D61. - 202/1100 12 min TLM outage from TGC failure at D61. (Recoverable?) Coordinated Operations: ---------------------- o 3-day collaboration -- Saturday, Sunday, & Monday -- initially between EIT and Big Bear Solar Observatory (BBSO), to study transient structures in North Coronal Hole. EIT can take image sequences for 44 mins every 6 hours. CDS, SUMER, and UVCS extending collaboration by making plasma diagnostic measurements of target area and plumes. BBSO observing time is about 1400 to 1900 UT. SOHO observing times given below in instrument status/plans. Instrument Status/Plans: ----------------------- o CDS: nominal. - Supporting BBSO/EIT coronal hole study today by mapping the target area, with pressure and temperature measurements, during SUMER times. - Plan for tomorrow open at this point. Will probably study active region coming over east limb for 8 hours, starting at about 0700 UT. Target location at that time expected to be 794 arcsec E, 182 arcsec N of Sun center, based on EIT images. Then may return to N. Coronal hole study. o SUMER: nominal. - North coronal hole study for 12 hours today (1400-0200 UT on the 21st), 6 hours Sunday and 6 hours Monday, from 1200 UT. SUMER will map north coronal hole from 2 arcmin inside the limb to 3 arcmin above the limb (= approx 1.2 R_Sun from Sun center), in Fe XII, N V, and Mg X at 625 A. - At 0200 UT on 21st, will begin FIP-effect study (to look for coronal abundance pattern based on First Ionization Potential of the elements) at Sun center (in lieu of active region target), and then on _South_ coronal hole beginning at 0200 UT. - Then polar plumes in North coronal hole again at 1200 UT. - Full Sun map tomorrow (Sunday) evening. o UVCS: nominal. Will study polar plumes in north coronal hole from about 1700 UT today (the 20th) through about 0200 UT on the 22nd, skipping the usual synoptic program tonight. Aligning the visible light channel on a plume, with 14 arcsec filed of view. Will observe at 2.6 R_Sun, then at 1.7 R_Sun (from Sun center) in Mg X at 625 A, O VI, Lyman alpha, and Si XII, for FIP-effect study. o EIT: better than nominal. Getting images again after recent LASCO/EIT software upload. - Now has more onboard flexibility, such as binning pixels in successive images without needing to reboot the onboard processor, summing images onboard, and ability to make two cal lamp tests instead of just one. The ability to bin pixels means that images for monitoring can be brought down in 100 sec instead of 20 min. - There is a ghost image of the bright limb of the Sun, with position fixed on the CCD, which disappears with bakeout. It is estimated that about 20 Angstroms of water builds up, leading to about a 30% efficiency loss in about a month. Past bakeouts of one or two days' duration have been successful in removing ghost and improving transmission. a one-hour bakeout will be tried. If successful bakeouts might be done weekly, with an anticipated 3 or 4 hour recovery time. o MDI: nominal. Near the end of the 2-month continuous dynamics period. Will spend the last 3 days getting alternating velocity and continuum images rather alternating velocity and line-depth images. Plan or Schedule Updates: None at this time. ------------------------ Meetings: -------- No daily meeting tomorrow. Meeting on Monday at 10:00 EDT. AOB: --- Reminder that there will be CELIAS TSTOL commanding from about 1430-1500 UT tomorrow (Sunday).