From Jay.M.Pasachoff@williams.edu Tue Aug 14 11:47:36 2001
Date: Thu, 02 Aug 2001 14:22:45 -0400
From: Jay.M.Pasachoff@williams.edu
To: Bryce.A.Babcock@williams.edu, lhawkins@brashear.phys.appstate.edu,
     Gabriel.B.Brammer@williams.edu, roban@sccs.swarthmore.edu
Cc: Daniel.B.Seaton@williams.edu, plsmith@cfa.harvard.edu
Subject: briefing on our CfA visit of 8/1


To: Bryce, Lee

cc: Gabe, Roban, Peter

Gabe, Roban, and I went to Cambridge to the CfA yesterday and were
joined there by Dan.  We met with Peter Smith and John Kohl of the
UVCS experiment.

When Roban picked up the filter wheel to bring it, things were
rattling around inside.  When I opened it, there, unfortunately almost
all the filters were loose and were moving around.  Several were
chipped.  None of the Polaroids were in their original positions, a
particular disappointment since we hoped to remeasure their angles.  I
wish
a) the filters had been potted in.  What was holding them in?
b) padding had been inserted between the filter wheels for shipment.
c) the filter wheels had been hand carried home.

I learned that apparently the Mars data, which were taken the night
before through the Polaroids, was deleted by mistake.  Lee, is it true
that there is no backup for that?  Further, apparently we forgot to
take more Mars data through the Polaroids the night after the
eclipse.  So we have no calibration data on instrumental
polarization.  The Jupiter data during the eclipse weren't through the
Polaroids, so are good for radiometric calibration but not the
polarization.

Peter is surprised that he ever thought we needed the other focal
reducer, since the one we finally used gave a perfect field of view
for displaying 2.5 solar radii.  They also have some observations at
1.8, but LASCO has only 2.5, which is why we needed 2.5.  I have a
copy of the calculations of their student Bogdan Valcu.

I have asked Roban to write out for me
a) the list of filters in each filter wheel in order
b) the list of exposure times and of dead times, so that I can see the
whole sequence.  [Lee, you may have this already.]

Roban and Gabe: can you please weigh
a) the camera
b) the filter wheel
c) the CCD.

We would like to set up the apparatus entirely, including the CCD, and
get observations of the Moon through the Polaroids.  Then we can see
what we get for the instrumental polarization.

The CfA group is now calibrating the eclipse setup of Shaddia Habbal,
which is a long lens attached to a CCD.  They have it on a rotating
mount, rotating along the axis through the middle of the lens, to
eliminate asymmetric effects in the system.  That should take them
perhaps 6 weeks.  The light, before entering the system, hits a diode
that characterizes the beam (one pixel) and then goes into the lens.
They take measurements at 60 degree angles around.

For our 10" telescope, we would need to machine a heavier and bigger
mount to allow us to rotate the telescope.  We could probably use
their gimbels.  If their post-doc Adrien works with the current setup
for a month or so, he can recommend what changes we would have to make
for ours.  Potentially they can start setting it up during the fall to
give time for our shop to machine the mount in the late fall, and then
Gabe can make measurements for several weeks during Winter Study,
after the January AAS.

Any of the attendees is welcome to make additions to this summary.

 jmp
 8/2/01