Documentation > SXT Observation Notes > this page

As the Sun Sinks Slowly in the West

Image name: Sunset_941215.1020.png (click image to enlarge)
Image size: 16.7060 KB (1024x982)
Date submitted: 16-Dec-1994


     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

					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
         ---- --- ----- --- --- -- --- --- --- ---- --- --- --- --- --- --- ---
   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

To the YLA Guide front page with side-frame
To contact us: