The TRACE observations are proposed to be acquired as the addition to this SOHO JOP. The reason is to perform imaging with higher spatial and temporal resolution comparing to the CDS and EIT instruments.
The limited FOV and the data compression are proposed in order to speed up the frame cadence. Therefore the data will be taken only in the nearest vicinity of the SUMER and CDS FOV. The proposed data compression should be nearly lossless.
The main TRACE sequence part is scheduled as a repetition of image acquisition in 3 wavelengths in a cycle for a longer time interval covering the SOHO observing run. The secondary TRACE sequence part should acquire almost continual flow of images in each selected wavelength in order to check possible changes on the shortest time scales. The TRACE visible continuum image is also included for the fine co-alignment of TRACE images with the SOHO data.
In case of some time schedule constrains the proposed TRACE operation
(the sequence parts and their parameters) can be modified according
to the other TRACE proposals.
Preliminary setup :
FOV (EWxNS) : 127.5'' x 255'' (256 x 512pixels),
compression : TraceQ=1, QT=1, HT=0, 3.85 bits/pixel
The main sequence part : acquisition of images in 3
wavelength channels in a cycle. The order can be modified to
optimize the quadrant shutter and filter wheel operation.
selected channels : 1/ 5000 Å continuum (4.0-6.4x10 K)
/ 1216 Å Ly (10-30x10 K)
/ 171 Å Fe IX-X (160-2000x10 K)
estimated exposure times : 1/ 5000 Å : 0.1 sec (for 1/2 well or 2084DN)
/ 1216 Å : 15 sec (for 1/10 well or 410DN)
/ 171 Å : 15 sec (for 1/20 well or 205DN)
estimated dwell time : readout + compression + data processing +
compression + transfer to mass memory : 1.25 sec
quadrant shutter movement : <=1.6 sec
filter wheel movement : <=1.7 sec
focusing : 2 sec
total time of the observing cycle : 1x1.25 + 2x13.75 + 3x5.3 = 44.2 sec
estimated data volume per hour : 14.4MB
The secondary sequence part : the sequential acquisition of images in channels 2/ and 3/, each for at least a half an hour. This will lead to almost 100 duty cycle in channels with the following parameters :
exposure time : 15 sec
estimated dwell time : none
total time of the observing cycle : 120 exposures x 15 sec = 1800 sec
estimated data volume per hour : 2 x 7.57MB = 15.14MB
total duration of this sequence part : 1.5 hours