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- Shutterless sequences must be run when in telemetry submode 6 (15.8 kb/s)
- 2 callamp images before and 2 after the runs (on the same day)
- 1 reference image in the same bandpass (full-field, full resolution, take-normal) just before and after the sequence (last one before and first one after).
- filter wheel position: always AL+1 (no change, no half- blocking filter)
- readout port: B (no change)
- handling of flares:
- prior to the sequence, contact by telephone with Kitt-Peak Observatory
to check for current global flaring probability for all active regions.
--> decision to run or postpone the sequence - onset monitoring should be done by the planner using GOES X-ray fluxes
--> either send a command to interrupt the sequence (risk of hanging the LEB) or rebooting the LEB.
- prior to the sequence, contact by telephone with Kitt-Peak Observatory
to check for current global flaring probability for all active regions.
- segmentation of the whole shutterless sequence in 40-60 min runs. Gaps
should be kept below 5-8% of the total sequence duration:
- LASCO C2 images can be inserted in those intervals.
- Each subsequence can restart when the telemetry buffer occupation has dropped back to the level that was reached when the last subsequence finished. It is only required to start with an empty buffer before starting the first subsequence.
- Each subsequence starts with an "open shutter" command, followed by a delay. This delay can be any (short) value when CCD clears are used, but must be equivalent to the effective exposure time minus the programmed exposure time (i.e. to the processing time) when no clears are used.
- Each subsequence finishes with a "take-normal" exposure of the same subfield (this closes the shutter).
- submode 6 telemetry rate:
- 15833.2 bits/s
- 1130 pix/s
- 66 blocks/min
- 1 EIT block: 1024 pixels = 14336 bits uncompressed
- telmetry buffer capacity (16 bits/pixel):
- 25000000 bits
- 1562500 pixels uncompressed
- 1525 EIT blocks uncompressed
- 4 ff fr images compressed
- telemetry buffer flush time: 23 min 20s = 1400s
- default commanded exposure times (Al+1):
- 171A: 5s (1.25s with 2x2 binning)
- 195A: 10s (2.5s with 2x2 binning)
- 284A: 120s (30s with 2x2 binning)
- 304A: 30s (7.5s with 2x2 binning)
- expected compression ratio:
- 171A: 2.5 ?
- 195A: 2.5 ?
- 284A: 2.5 ?
- 304A: 2.5 (measured)
- Measured processing time:
- no compression: 1024 blocks in 260s, 0.254 s/block
- compression (factor 2.5?): 1024 blocks in 365s, 0.357 s/block
- Estimated processing time:
- Nu= number of uncompressed blocks
- Nc= number of compressed blocks
- CR= compression ratio
- CCD readout rate:
- normal readout: 50000 pix/s
- 1024 columns in 20.97.s
- 20.48 ms/column
- line dump: 60 micros/column, 61.44 ms/whole CCD
- CCD clear: 200 ms
- Solar disc coordinates:
- Sun center (2000/11/17): (507.7,518) -> (LOC coord): [509,570]
- Radius= 374.5
- Limb positions: (133.2:882.2:143.5:892.5) -> (LOC coord): [134:883,195:945]
a) processing: Nc x 0.254s
b) compression: Nu x 0.638/CR s
T (s) = Nu * (0.254/CR + 0.638/CR)= Nu * 0.893/CR
Possible other schemes considered in the past:
-
- 1) 304 (EIT) - 171 (TRACE)
- 2) 195 (EIT) - 171 (TRACE)
- 3) 304 (EIT) - 171 or 195 (TRACE)
- 4) 171 (EIT) - 171 (TRACE)
-
- Dec 2000 : 304 (EIT) - 171 (TRACE) [A]
- Jan 2001 : 171 (EIT) - 171 (TRACE) [B]
- Feb 2001 : 195 (EIT) - 171 (TRACE) [C]
- Mar 2001 : 304 (EIT) - 195 (TRACE) [D]
- Apr 2001 : 171 (EIT) - 195 (TRACE) [E]
- May 2001 : 195 (EIT) - 195 (TRACE) [F]
- 6 EIT/TRACE modes (A->F) = cycle twice a year but 3 EIT wvl = cycle 4 times per year.
-
- 1) 304 (EIT) - 171 (TRACE)
- 2) 195 (EIT) - 171 (TRACE)
- 3) 304 (EIT) - 195 (TRACE)
- 4) 171 (EIT) - 195 (TRACE)
-
- 1) 304 (EIT) - 171 (TRACE)
- 2) 195 (EIT) - 171 (TRACE)
- 3) 171 (EIT) - 195 (TRACE)