ARNE Mark IV

[<aah@nofs.navy.mil>]

The Mark IV is taking data, though I am slowly working
through a pile of hardware and software issues (plus it
is full moon to boot).  As an example, I've posted a file:
ftp://ftp.nofs.navy.mil/pub/outgoing/aah/tass/sa92v.gif
which is the difference between instrumental measures
and true V measures for the Landolt standard region SA92,
taken around moonset on 000910 with a 152 second exposure.
The mean value of the difference (~2.5mags or so) is irrelevant;
it is the scatter that is important.  Note that to about
V=13 the points scatter around a pretty constant value,
with some of the scatter due to Poisson noise and some
due to the slight offset of the TASS V filter from the
standard filter bandpass (the stars range 0.422 < (V-I) < 1.836,
and I haven't done any transformation yet).
Still, the RMS error is just a couple of percent.
However, after V=13 you see a definite systematic error
that looks like a magnitude effect.  I'll have to look
at that in more detail.
  The system is taking ~2GB per night of 1600 square degrees
of sky during photometric conditions.  I'll post some of
the images later in the week for those who want to try some
processing.  My analysis suffers greatly from an overload
of other duties.
Arne