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Joint Observing Programs
With SOHO and TRACE
January 8-20, 2007
- Objective
To characterize the temperature, dynamics and statistical distribution of polar coronal jets recently observed by XRT.
- Observables
XRT: High cadence observations in a single filter (Al-poly) with a 1024 × 384 field of view. 16.34 sec exposures have already been tested for this type observation. Also, context images with a field of view of 1024 × 960 (offset relative to the pointing position) are required to extend the field of view to 0.7 solar radii. This is the expected slit position of the UVCS instrument on SOHO,
EIS: Slot images in Fe VII - Fe XV and He II are appropriate. The smaller slot (40") should provide the best temperature information while extending the field of view to a size large enough to capture some of the events. A 'picket fence' type raster scan may also be appropriate if 6-8 slit positions are selected at x positions [-15,-10,-5,0,+5,+10,+15] arcsec from the zero longitude,
SOT: G-band and Ca-H at high cadence full resolution with vector magnetograms,
UVCS/SOHO: spectral line intensities for doppler dimming and velocity measurements with a slit position orthogonal to solar north,
CDS/SOHO: Observations with the 2" slit using the line list in JOP 146. It would be useful to use the same slit positions as EIS,
LASCO/SOHO: to be decided,
TRACE: 171 1024 × 1024, Q4 @ 30s cadence with 1600 or 1550 & WL in context.
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Pointing Requirements
Previous observations of the North and South polar regions have produced a very small sample of the distribution of events spatio-temporally. To increase the statistics on these events a minimum time at a pole, north or south, should be 40 hours of observations by all instruments within the two week period.
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Data Rate
High Cadence in a single filter is paramount for XRT. Lack of observations due to an increased load on the data volume could limit access to the statistics we wish to develop. My calculations indicate an increase from 15% of the science telemetry to 22.5% would be sufficient to run XRT at full speed for 8 hours a day for the polar observations and would include room for synoptics and a very slow (1 image per 3 minutes) cadence outside the polar observation time.
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