SOHO SPWG Minutes
SPWG, FRIDAY JANUARY 23, 1998
Chair: Piet Martens (ESA/SOC)
Notes: Laura Allen (NASA/SOC)
Attendees: Joan Hollis (SOC), Vicente Domingo (ESA), Joe Gurman (EIT), Julia Saba (MDI),
Chris St. Cyr (LASCO), Andrzej Fludra (CDS), Silvano Fineschi (UVCS),
Harold Benefield (FOT), Carrie White (FOT), Helmut Schweitzer (ESA),
Jean-Philippe Olive (MATRA), Jeff Newmark (EIT), Luis Sanchez (ESA),
Chris Haskell (CDS), Eric Quemerais (SWAN), Bernhard Fleck (ESA),
Dan Muhonen (NASA), Dominic Zarro (CDS), Dan Moses (EIT/LASCO),
Sarah Gibson (WSM)
1. Review of action items
- PI teams to respond to EIT Offset proposal (if distributed)
Ongoing: Awaiting final approval, to be known by January 30.
- Roll maneuver: Teams to submit detailed requirements to the SOC by January 22
After some discussion about inputs received (added to the end of the minutes
below), it was decided that PI's would be asked to waive their 16 hour
helioseismology constraint. Concern was that we are ending our nominal mission
and DSN contacts may not be as kind to us in the future. In summary, we will roll
once stopping at 30 degree increments with dwells of 33 minutes at each stop for CDS.
At two positions (+60/-60), LASCO needs 1 hour and CDS requested 6 additional minutes,
to total 66 minutes. After we have completed one roll around the solar circumference,
we would move to the +90 position which CDS again requests more time at
(8-10 hours) which is the minimum time necessary to obtain satisfactory photon
statistics for polarization measurements. E-mail after the meeting
resulted in plans for a +90 degree dwell and end of MDI Oblateness roll.
Plans are as follows:
Monday, Apr 13 - Gyro Cal and possible Momentum Management
Tuesday, Apr 14 - E-W Offpointing (3 hours), for EIT calibration, if agreed by SWT
Note: We would have to wait 30 hours after last
thruster firing for CDS to open doors and
begin observing before the offpoint would start.
As they plan for science observations during offpoint.
After the offpoint, CDS to perform 13.5 hour observation
Roll should not begin before that observation is finished.
Wednesday, Apr 15 - Oblateness Roll (16 hours max):
MDI Oblateness Measurements,
SWAN Cross-calibration, CDS, SUMER polar scans
Note: This roll would need to be timed such that
the long dwell (at +90) after the oblateness
roll would begin at 8 UT for SUMER collaboration
with Tenerife (see inputs at end of minutes).
After the roll, CDS to perform 13.5 hour observation
then allow usual 2 hour period of NRT for instrument
safing preparation prior to burns.
Thursday, Apr 16 - Station Keeping/Momentum Management,
Reaction Wheel 4 Maintenance
Friday, Apr 17 - SSU Software Patch -- done in RMW mode.
Timeline submitted to SWT
SVM Reserved (NM --> RMW) 0.5 hours
10 Rolls X 48 minutes
(33 min NRT dwell + 15 min slew) = 8 hours
2 Rolls X 75 minutes
(66 min NRT dwell + 15 min slew) = 2.7 hours
Roll to +90 0.5 hours
Dwell at +90 (timed so start of dwell is 8 UT) 8-10 hours
Roll Back to Nominal position 0.5 hours
Return to Normal mode 1.5 hours
21.7 - 23.7 hours
Note: If we have to do an offset, like last time would also add
slightly to "off-nominal pointing constraint"; but this would
be done in normal mode.
Contingency plans if SWT does not accept the above plan will be worked out
in the coming days.
- Upgrade of Submode 3: status report
A new submode 3 is being created which would give CDS 135 packets and
LASCO/EIT 38 packets. Saab began testing and it seems to work; we'll
have confirmation in 1 or 2 weeks. Therefore, could possibly test in
February and be ready for the first two weeks in March.
See: http://sohowww/~soc/submode.html for current submode configurations.
- P. Martens to contact Dr. Kariyappa to learn what observations
he desires from which SOHO instruments and what observations he will provide.
Midnight in India during eclipse, so SOHO will not comply with observing
request. We will keep Dr. Kariyappa informed since he asked.
- P. Martens will write up a summary eclipse plan based on input
from SOHO teams and outside coordinating observers.
Completed: See SPWG e-mail message # 267 and the following URL:
- Joe Gurman to coordinate observing plans for SOHO support of
flight of rocketborne ISAS XUV Doppler Telescope (January 31).
2. Boundary conditions for the coming month
- All of February: Continuous Contact
- February 1: TR maintenance/memory dumps
- Submode changes: Submode 4 agreed for Feb. 8/9 and 15/16.
Submode 5 for eclipse observations
3. Preview of future months
- Presentation of Whole Sun Month II was given by Sarah Gibson.
Preparation sin advanced state given that WSM II is 6 months ahead.
For updates see:
- EIT Off-set plans.
Same as outlined in previous SPWG meeting minutes.
Helmut Schweitzer mentioned there may be a possibility
of getting past the 30 arcminute FPSS constraint and perhaps doing
a 44 arcminute offpoint in one direction only for EIT. This is
still being investigated. What they desire is below:
Ideal - A single offpoint 44' east OR west. Solar disk completely outside
EIT field of view. This allows us to use our "CLEAR" filter
wheel position (i.e. no additional filter) for the deep
exposures. This is currently our best calibrated filter wheel
position, since most of our data have been obtained there.
Sufficient - If spacecraft constraints restrict the offpoint to < 30 arc min,
as currently still appears to be the case, we can use a 25 arc
min offpoint in both east AND west directions. The portion of the
the solar disk still in the nominal EIT field of view at each
offpointing will be obscured by the east and west partial
blocking filters, but we then need an offpoint in each direction
to provide data for all CCD pixels.
- CDS Proposal for Submode 3 in March: Agreed if new submode 3 tests in February
- TRACE update
The ECS software can now accept TRACE IAPs and produce KAPs with TRACE
plans included. Software on WWW that gives target information reads
information from the KAPs and displays them on the WWW. TRACE summary data
will be integrated with SOHO summary data.
The following is summarized from emails from Ted Tarbell:
Dates for the next TRACE Operations Simulation were changed and now
planning to have that sim on February 10-13. Coordination with SOHO will
be a priority this time, now that the distraction of running the flight
instrument during the sim is no longer possible.
The TRACE launch is scheduled for March 6. There are still some open
issues between NASA and OSC (the Pegasus XL company), but they are not
showstoppers. There is one more Pegasus launch before TRACE, SNOE scheduled
for Feb 3 or so; it must happen ~on time for TRACE to maintain its launch date.
The TRACE spacecraft is scheduled to ship from GSFC to Vandenburg next Monday.
It will begin commissioning (with sunlight) in late March and scientific
observing in the 1st or 2nd week of April. Collaborations and JOPS with
TRACE and SOHO instruments are expected to start in April. Suggestions for
JOPs are still very welcome--it's not too late; email to you, me or Karel Schryver
(email@example.com) can start the process. I will attend the
February SPWG on Feb 20 to give a more detailed presentation.
The TRACE 30-day plan for its highest priority observations in the early
phase of the mission can be seen at:
- See Monthly Calendar at
4. Priorities for the coming month
a) Individual instrument plans
MDI - Continuous contact, the third month discussing bringing down high
LASCO - Eclipse is highest priority for them. Will be taking C1, C2, C3
polarization sequences. Showed gif image of plans for eclipse:
see SOHO eclipse page mentioned above
Can see when LASCO and EIT observations occur. EIT taking a synoptic
set at areas indicated in chart.
Discussion of backup antennas and turning SSR on. Request will
be submitted for backup antenna as turning SSR on will hurt MDI's
continuous contact and planned magnetogram support.
Perhaps, JOP067 during week07. Will check back with team
and have them e-mail SOC.
EIT - Line ratio CME watch (171 & 195) priority as soon as DSS-27 fixed.
They will perform a bakeout during the weekend of the power outage.
UVCS -- First week of February doing an observation with visible light
channel and getting ready for eclipse. For eclipse, they will use
the visible light channel and focus on coordination with Habbal
expedition that takes visible light Pb images. They will take
polarized brightness of the green line above 1.3-1.4 Rsun and
doing offpoint to look at 1.3-1.4 Rsun and characterize streamer
region where green light to be strong.
CDS -- During period when SUMER asked for submode #4 will be doing long
exposure GIS studies.
- First week of Feb - Test of CDS eclipse Studies (Phil Judge).
CDS to run modified form of LARGEBP2.
- CDS Synoptic and Monitoring Activities, as usual.
- CDS Quiet Sun Studies and Off-Limb Studies - two long duration
activities at weekends.
- 8,9,15,16 Feb. (during Submode 4), GIS deep exposures above
- Extended observation of a limb active region,date TBD.
(Leader: Fludra). Up to 12 hours including a deep raster
and a movie. Maybe to be done twice on successive days.
Target of opportunity.
Eclipse Support Activities from CDS. Our current plan is the
following: We are committed to a collaboration with Phil Judge and
the NOAO/HAO activities. A target at C.M. will be chosen about 7
days prior to the eclipse and we will spend about 2 hours on it
each day making 4x4 maps in selected lines. On the day ofthe eclipse, we
will map the same region on the limb. After the eclipse, we will continue
to map the region as it passes from sight. HOWEVER, if on eclipse day
an east limb target is better, we will map it and track it to C.M.
over the next 7 days. The entire support activity takes about 2 hours per
day - encompassing the eclipse period on February 26th. In addition,
we will produce some raster 'mosaics' running along either the west
or east limb, prior to and after the eclipse. Since SUMER will be
operative, we anticipate medium rate telemetry.
b) Intercalibration activities
- Intercal001 to be scheduled
CDS requests a designated date for a run of Intercal 1, even
if all instruments will not participate. (If necessary
CDS will run ICAL1 alone, for continuity of NIS/GIS observation).
Week 06 was chosen to run ICAL001, a day will be determined at
the weekly meeting.
c) Joint observing plans
- Eclipse Observation Plans
for eclipse related information)
- JOP018, Sunspot Velocity Fields
- 9 February to 1 March - JOP 18 Sunspot Studies, as Target of
Opportunity (Per Maltby). CDS Studies as before. Target
is a clear sunspot group on disc. (Eclipse takes priority!).
5. JOPs status
6. New JOPs
- JOP075: Time Variation and Dynamics of Active Region Loops,
- JOP076: CDS LASCO Mauna Loa Streamer Study for Second Whole Sun
Month Campaign, Sarah Gibson
- JOP077: Time Evolution of Streamers, Richard Frazin
- DSS 27, telemetry and commanding
Because of succesful equipment fix on DSS-27 on Friday (January 23)
evening, information reported at the SPWG is obsolete.
Note: we will not have DSS-27 scheduled from February 9 to beginning
- Next SPWG Friday February 20
Inputs from Teams regarding roll maneuver:
SUMER -- Wants a 90 degree dwell for three observations.
(1) Spicules in a coronal hole (north or south). Duration approximately 3 h.
As mentioned before this is a cooperation with Tenerife and, therefore,
it would be required to have the Sun up there preferably in the
(it is pretty obvious, but it might be worthwhile mentioning that our
spicule cooperation with Tenerife, which is getting along alright as far
the telescope is concerned, is only feasible, if we are at 90 deg for
some hours between, say, 8 and 12 UT).
(2) Density and temperature diagnostics (Si VIII, Mg IX observations in plumes
and inter-plume lanes). Duration 2 x 1 h.
(3) Reference spectrum in coronal streamer near the equator with slit
perpendicular to limb. Duration 5 h desirable, but shorter periods could
There are no absolute time requirements for items (2) and (3).
This gives a minimum dwell time of 7 h and a masximum of 10 h.
We can accept +- 90 deg positions.
CDS -- We anticipate taking polarization measurements
much as in March 1997. At each 30 degree stop we plan to
run 1-2 Studies - possibly the OFFLIMB Study followed by
the SING2W Study as before. Total duration is 32
minutes, and one extra minute is required to manually start the study.
Prior to the roll, and after the roll, we plan to run a long duration
raster as before. We have two points to raise:
(i) Again, a reminder that we do not open the door for
24 hours after a burn. Our 'deep' pre-roll raster takes
13.5 hours and any burn planned prior to the roll had better
be at least 38 hours before the roll.
(ii) The sequence is being considered by Andrzej
Fludra and Roger Thomas so they can provide more
input at the SPWG meeting.
LASCO --- LASCO requests that the dwell be increased to 1 hour for two of the
twelve angles. For purposes of consistency checking the polarizers
in each of the LASCO telescopes we require a 1 hour dwell at +60
degrees and -60 degrees roll angles. Best regards. CSt
SWAN --- Swan's request for the April 98 roll.
Our preferred maneuver would be the longest dwell possible
at +/- 90 degrees (actual signe to Be Defined).
Otherwise, we would prefer to have as little stops as possible
with the shortest dwells possible. Longer dwells at +90 , +180,
and +270 can be managed.
For last year's roll, there were two 360 degree rotations .
This year only one would be much better.
>From rock@quake.Stanford.EDU Fri Jan 23 12:48:57 1998
Date: Thu, 22 Jan 1998 18:11:23 -0800 (PST)
From: Rock Bush
To: SoHO SOC , firstname.lastname@example.org,
Subject: MDI activities proposed for SOHO manuevers/roll in April
The SOI-MDI team requests a 360 degree roll of the SOHO spacecraft as part
of the activities planned for April 1998. Measurements of the solar limb
would be made by the MDI instrument during the roll in order to determine
the solar oblateness and temperature variation. These measurements would
be similar to those performed during the March 1997 SOHO roll activities.
A repeat of the measurements from last year is valuable for determining
any solar cycle variation in these parameters.
The requested activity should consist of a single 360 degree roll of the
SOHO spacecraft about the axis pointing to the center of the sun. The
spacecraft should operate in RMW pointing mode during the roll, and use
reaction wheels to adjust the roll angle. One complete roll is requested
with stops at increments of 30 degrees with a 20 minute dwell at each 30
degree delta stop. Because the oblateness measurements are independent of
the roll sequence, the spacecraft can make either a "positive" or
"negative" roll about the +X axis. SOHO should remain in VC2/VC3 telemetry
mode for the entire roll, and VC2 telemetry is requested for as much of
the 360 degree roll as is practical.
Based on the previous March 1997 roll, a 30 degree roll should take about
15 minutes (allowing for roll determination). This time to roll combined
with a 20 minute dwell for 12 steps gives a predicted duration of about 7
hours. The remainder of the roll activities can then be dedicated to SWAN
The primary observable during the 360 degree roll is the MDI full-disk
computed continuum in order to measure the solar limb. Dopplergrams and
magnetograms may be obtained during the roll for instrument calibration
In addition, the MDI team supports the spacecraft offpoints requested by
the EIT team for calibration and will accept a 3-hour interruption in the
Structure program. We request that the offpointing not be done
immediately adjacent to the planned roll maneuver. Having the offpoint on
the day prior to the roll as outlined in the strawman plan is acceptable.
Due to the magnitude of the proposed offsets (25 arcmin above the East and
West limbs), it is unlikely that useful MDI calibration or science data
can be taken during the offpoint dwells (the MDI high resolution field of
view will be entirely off the solar disk). Nevertheless, the MDI
instrument will continue observing during the offpoint, and we request VC2
telemetry if possible during the offset adjustment in order to monitor the
The ISS loop will need to be opened throughout the offpoint maneuver,
either by the FOT via TSTOL procedure or by the MDI team using NRT
commanding. The loop should be opened just before the offpoint begins and
closed as soon as possible after nominal pointing is resumed so that the
Structure data are not degraded for any longer than necessary.
Regards, Rock Bush & Julie Saba