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Image name: Sunset_941215.1020.png (click image to enlarge)
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Date submitted: 16-Dec-1994
AS THE SUN SINKS SLOWLY IN THE WEST
Here are the results of the sunset flare mode experiment which ran
during pass 4 on 15-Dec-94. The x-ray and visible (diffuser) images
have been dark signal corrected by the average of 16 DPE=2 dark frames
taken at the time of the experiment. This will leave a small but
insignificant dark current signal in the x-ray images -- probably
accounting for the tiny rise in the final x-ray image in these
exposure-normalized data. It is interesting that the visible signal is
not absolutely flat. I don't know whether this is from statistics or
shutter error. I had anticipated a bi-level structure but this is more
noise-like than that.
The upper RH plot is a time expanded version of the upper LH plot.
Unfortunately, there is a data gap (probably a flare mode patrol image
as I forgot to set the interval to 255) just at the critical time for
the visible signal. However, it looks as if a 15-30 sec window for
choice of 5 sec (DPE=25) SFTs for the AlMg filter -- under these B-level
solar conditions. We are targetted on AR7815 which is fading from a LDE
flare which peaked at around B4 at 09:50 UT. I believe that the
interval 15-25 sec before night should work for all filters under all
solar conditions except maybe large flares.
The lower 2 plots compare the FEM and TFSS time to sunset data for
this sunset. The two data sets are strictly correlated, within the 2
sec granularity of the TFF data, until the last 3 frames when the TFSS
loses it. Based upon this I agree that the FEM times are what we should
use for selecting SFT files but that we should tighten the time
criterion up to 15-25 sec before FEM night.
For your reference I have appended the relevant part of the SXT
table used for this experiment below. I will try and run this one more
time before I depart ISAS on 22-Dec-94 but with an increased diffuser
frequency.
Loren Acton 12/16/94
****** Table # 1173 (File: $DIR_SXT_TABLES/btb941215.064851)
****** 941215 PASS-2 ARS1, STD+LONG, 2X2 PFI, TERM=3
****** UPLOAD 15-DEC-94 @ 1546 JST THU, FLARE-MODE TERM XPT LWA
-------------------------- PFI Entry Table #0------------------------------
# Loops (2,3,4,5) = 1 3 1 1
Flsh Sht F#0 F#1 F#2 A- DPE Img Res ROIT Alt Alt AEC AEC AEC AEC AEC
B/A B/A Door Typ Lev ULT LLT UAT LAT
---- --- ----- --- --- -- --- --- --- ---- --- --- --- --- --- --- ---
1-1
2-1
2-2 411 M AM/Op - - Op 2 Dark FC1N 8 Off 0 Off - - - -
3-1 411 M AM/Op - - Op 21 Norm FC1N 8 Off 0 On 185 140 0 16
3-2 411 M Op/NB - - Op 2 Dark FC1N 8 Off 0 Off - - - -
3-3 411 M AM/Op - - Op 21 Norm FC1N 8 Off 0 On 185 140 0 16
3-4
