Sbig SEEING MONITOR User Manual

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All Weather
SEEING MONITOR

Professional observatories often
employ a monitor to determine
the quality of seeing each night.
This can be useful in helping to
decide whether to take certain
kinds of images, or whether to
image at all. If you happen to be
at the observatory you can
sometimes just look through an
eyepiece and see whether the
night "looks" good or not. But
more and more of our customers are mimicking professional observatory installations
with remote observing sites and fully automated observing systems. Remote can mean
anything from a few meters to a few thousand kilometers. No matter where one
observes, it is often a time consuming matter to get ready for a nights imaging session. It
would be convenient to know before hand what kind of results one could expect. Even if
the expectation was that the night's seeing would be no better than several arc seconds,

Figure One: Seeing Monitor

the type of
imaging one
decided to set up
for could be
changed to make
the best use of the
conditions
available for that
evening.

SBIG has
developed an
automated unit
for monitoring
and logging the
seeing

Figure Two: 10 second image of

Celestial North Pole and Polaris

throughout a

night. The
Seeing Monitor, pictured on the right, uses the same ST-402ME camera board
and weatherproof box as the Meteor Camera with some different optics and

different software. The Seeing Monitor is intended to be set up once and left
outdoors for an indefinite period.

The Seeing Monitor uses an uncooled, shutterless version of the ST-402ME
mated to a 150 mm focal length F5.3 lens inside the weatherproof box. The
box also contains a USB extender, and a 12 VDC power supply for the camera.
The window in the top of the box is clear. The window is heated to prevent
condensation on the outside. The USB extender allows operation up to 150 feet
(50 meters) from the controlling PC. The lens and box is permanently pointed
at Polaris by the user. It is assumed the user will mount posts in the ground
outside his observatory or home for this purpose. Roof mounting is not
recommended because small vibrations from the building may affect the
monitor's measurements.

When properly aligned, one will get an image of Polaris as shown in Figure
Two. Of course, Polaris is not eactly at the pole. The field of view is just large
enough that the entire orbit of Polaris about the north celestial pole can be
captured no matter what time of night the measurements are taken with the
camera set up on a fixed mount.

Figure Three shows a sequence of images over a night superimposed. The
position of the pole is now quite apparent.

Figure Three: Sequence of 10 second Images Superimposed