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Sun Backsights
From: Jeremy C
Date: 2011 Jan 20, 07:09 EST
From: Jeremy C
Date: 2011 Jan 20, 07:09 EST
I am trying to get the hang of these back sights, so I decided to go back
to basics and take a look at the sun.
It was about 35 minutes before transit when I took these shots. Due
to my schedule and available azimuths with a sea horizon, I decided to do this
instead. I reduced them as straight LOP's because they are outside the
acceptable limits of the ex-meridian tables.
I took one sight that appeared to be a lower limb which is actually an
upper limb observation. I then repeated the sight but took what appeared
to be an upper limb observation which was actually a lower limb.
Date: 20 January 2011
ZD-6
Lat 07-16.3'S
Long 072-26.8E
HoE 106 ft
IE 0.8 on the arc. Normal IC is -0.8'
Back Sight 1, Sun (UL)
Time 12h 49m 19s Local
Hs 104d 54.9'
My Intercept using my GPS fix as the AP is 0.7 towards 150.0 degrees for
sight 1
Back Sight 2, Sun (LL)
Time 12h 50m 20s
Hs 105d 20.7'
For sight 2 I had an intercept of 0.3 Away 150.5 degrees.
As an interesting note that these sights tie into the recent
discussion about the tabulation of the "d" correction. If you check the
bottom of the sun column, the "d" is 0.5. However the hourly change for
this observation is 0.6'/hour. I used the 0.6 for my entering argument as
I normally do.
Jeremy