Gemini 7 Technical Debriefing, 1965

150
star, you could not tell when they were over l a pping.
Lovell You had to have two stars of the same magnitude in lock .
So, I had practi ced and trained in the one with the
50- 50 split which I thought was a lot better than this
20-80 which we f i na l l y ended up with. And this a lso is
true when you t ook star t o Moon limb shots because they
had it arr a~.ged that most of the light ca.me from the Moon.
Eighty percent of the light passage was from the Moon and
they had f ilters t o cut that down . And 20 percent came from
the sta r . Well , the filters were not dark enough for
the Moo.n, and as soon as you got those stars somewhere near
the limb they just faded out of view. You coul d not see
it so you had a hard time getting star to Moon limb shots .
Lovell We noticed one big thing i n navigation with the sextant.
Wi th a ful l Moon , you a ~e going t o have a hard time using
the stars under the Moon. It just blanks out the light. I t
is j ust too bri ght, i t dims the stars and rui.ns your dark
adaptation. On no Moo.n nights or quarter Moon nights, most
of the stars come out and the na.vigatio.n i s a lot better.
We found out a l so on full Moon nights as we said before , tha t
we'd use the bottom Earth's hori zon, whi ch i s probab l y an
upper air horizon and had the sharpest l i ne of i dentification
f or angles.