SOHO Joint Observing Plan 012: Limb Prominences
CDS/SUMER Prominence Observing Program I
A. Poland, B. Schmieder
First Draft 10/25/94
Amended 26 February 2004 with this attachment
Purpose: To observe prominences on the limb with CDS and SUMER to determine
T, density, and v as a function of time in the prominence and surrounding
corona. An important aspect of this program, and a unique capability for
SOHO, is to observe the prominence material over a wide range of temperatures
to determine if observed visibility changes at one temperature are due to
density or temperature effects. A part of this question is does material in
small scale structure appear and disappear because of density or temperature
Another aspect is the material flow in small scale structures. Poland and
Mariska developed a syphon flow model for prominence development. This
observing program will help determine if the predicted velocity flows occur in
1. In SUMER: use the 1x300" slit.
set the wavelength drive to 1390 to 1410A in KBr; 690-695, 705-
place slit 1' inside the limb to measure the photospheric line
of S I at 1396.112A to get the "0" velocity wavelength
positioning(this will also compensate for solar rotation
Make 1 observation with a long enough integration time to
get a good line profile in the photosphere.
Move SUMER to begin prominence observations.
2. In CDS: Use the 90x240" slit, Make an observation with a 100 sec
exposure showing the limb and as much of prominence as
Move the image 90" so the field of view is just above the
previous image and make another 100s exposure. This will give
us a good overall view of the prominence and surrounding corona
over a wide temperature range.
Use the following lines in VDS: MgVIII 317, FeXIII 320, FeXIV
334, SiIX 341&345, MgIX 368, HeI 522, OIII 525, HeI 537, OIV
553&554, NeVI 562, HeI 584, OIII 599, HeII 304(2), MgX 624, and
Integration time is estimated at 100s/image
Windows need to be selected for 17 lines and 45 pixels/line in the
wavelength direction and 120 pixels/line in the spatial direction
for a total of 91,800 pixels/image(16bits/pix). This is
14.688Kbits/sec., so we need some data compression to accommodate
the rate of 10Kbits/sec.
When this set of observations is complete (200s) change the slit
to the 4x240" slit. Use the same lines as above but reduce each
window to only 10 pixels/line in the wavelength direction. Each
image is made with 100sec integration time. No compression is
needed. After each image move the slit up 4". Repeat this 30 times
for 120" coverage of the prominence and surrounding corona. This
will take approximately 50 minutes. Repeat as time allows.
3. In SUMER: Use the same slit and wavelength as in 1.
Send lines: (KBr) SiIV 1393, OIV 1399&1401, SiIV 1402, O IV 1404,
OIV 1407, and OIII 703(2): (Bare) NIII 685. Use 25 pixels in
wavelength direction, 360 pixels in position direction. This means
72,000 pixels or 720 pixels/sec or 11.5Kbits/sec. With overhead
this means we should use a compression such as a moderate log.
Make observations starting at the lowest position in the CDS
observation. Integrate at each location for 100sec. After the
first location move up 4" in synchronization with CDS if possible.
This would skip data on 3" between each image.
Examination of data indicates a change in the pointing scheme. For
example, some dynamic activity in a small area needs further study.
Same set of lines as in 2 and 3. Since we are looking at dynamics we
will try a shorter integration time ("m" - try m=30 sec for a test) with
the loss of faint lines.
SUMER slit :1" X 300" (try sending only a limited area defined by "n"
where n = 40" - this would mean a 40"x40" area)
Still use the step in 3 of 4" and repeat it over an "n" ( 40") area with
"m"sec integrations but with a repointing offset of 1 arcsec after
n/4 (10) scans and a back return to the initial position after 4 cycles.
A rapid survey of a region n X n (40 X40 ") will be done in
m x n/4 (5) minutes
A full image in 20 minutes. The area "n" ( 40") and the time m have to
stay as a free parameter that we could choose according to the
evolution time of the prominence.
CDS will scan a similar area (n x n) with
a slit 2 X 240 " with a step of 4 arc sec, a repointing offset of
1 arc sec after "n/4" ( 10) scans and come back after
The observing parameters are consistent with the currently known
characteristics of CDS and SUMER. The onboard software may not allow the exact
procedures to be followed, but that is under current development. These
observing parameters still need to be run through the commanding tools to
generate instrument commands.
Coordination with the other instruments on SOHO:
UVCS - nothing specified - nearby coronal observations would be useful
EIT - images in the EIT observed bands would be useful.
The EIT will provide an overview of the prominence area and limb environment
with images in each of four bands. A successive acquisition of the full
disk images followed by sequences of 8X* arc min field of
view centered on the Field of view of SUMER may be convenient.
LASCO - nothing specified - nearby coronal observations would be useful
Ground based observatories during the european daylight time:
MSDP (Meudon, Pic , Tenerife) Halpha (Mein, Schmieder,Roudier)
coronographs: PICO, HACO (Halpha), IR coro Fe XIII.(NOens)
THEMIS (after 1996 in MSDP mode with 2 lines)
coronographs of Wroclaw H alpha (Rompolt)
to have the survey of the neutral line along which lies
Huairou (Beijing- Dr Ai)
POtsdam (Germany, Dr. Hofman)
MEES (Hawaii) and MSFC (Hagyard)