Sky & Telescope - March 2024 - 68

S&T Test Report
access the internet. It was a seamless
operation for me, but a location with
poor cell service might have problems.
Chances are good that the activation
process will also include a notification
that a firmware update is available, and
it will take a few minutes to install it.
These updates happened several times
during my testing (as well as an update
of the iPhone app), each adding more
features to the Seestar and occasional
bug fixes. All were accomplished without
a hitch.
The only requirements for setting the
Seestar up outside are that the device
be level and its internal digital compass
is calibrated. The app will notify you if
these conditions aren't adequately met,
and there are built-in routines to help
you achieve both tasks. The date, time,
and location information that Seestar
also needs to find objects is gathered
from your phone.
A Brief Peak Under the Hood
Here's a quick summary of how the
Seestar's stargazing mode works. When
the sky is dark enough to show stars
(you need to be the judge of this since
Seestar doesn't know this on its own),
you use the app to select an object to
observe. There are several ways to do
this, including choosing from a list of
" tonight's best, " using a search function
that accepts common names and
designations of astronomical objects, or
using a scrollable sky map called SkyAtlas
that lets you position objects within
the Seestar's fixed 0.72° by 1.28° field of
view. As of this writing, there's no way
to select a target by its right ascension
Near right: Although the Seestar has four
rubber feet on the corners of its base, suggesting
it can be set down on a table, the device
must be elevated on its central pivot so that it
can rotate during operation.
 Far right: Seestar's 50-mm f/5 three-element
apochromatic objective, coupled with its Sony
IMX462 CMOS detector, provides a 0.72° by
1.28° field of view that is well suited for the
Moon, Sun, and many deep-sky objects. But its
relatively low effective magnification has limited
value for observing the planets. A built-in dew
heater is effective at keeping the objective free
of condensation.
68 MARCH 2024 * SKY & TELESCOPE
Seestar has observing modes for the Sun and Moon that can save still images and video on your
smart device used to control the scope. You can also save AVI-format video files of both objects to
Seestar's internal memory to be downloaded later and processed with astronomical video-stacking
software. These images of the Sun and Moon (taken last September 26th and 27th, respectively)
were made from 10-second AVI video clips processed with ZWO's free ASIStudio software.
and declination coordinates, but this
never proved to be a problem. I could
always find a nearby target that was
available with the other search methods
and then slide the displayed star map to
position my coordinates in the camera's
field of view. You'll be warned if your
object is below the horizon.
Once you have your target selected
in the SkyAtlas, you tap the GoTo button
and Seestar begins slewing rapidly and
very quietly to the appropriate area of
the sky. When it arrives, it snaps a quick
exposure of the star field (the exposure is
automatically adjusted if necessary) and
uses an internal plate-solving routine
to determine exactly where the scope is
pointed. The night's first target usually
isn't centered in the initial exposure,
so the scope automatically moves the
appropriate distance to center the target
and verifies it with another brief exposure.
This whole process usually takes
only a minute or two and is amazingly
accurate and totally automatic.
With the field centered, the Seestar
begins updating the app's display
with short exposures. You can use the
displayed image to fine-tune the field
of view with a virtual joystick that
appears on the phone's screen when
you hold your finger on the display.
Brighter deep-sky objects like M27 are
often faintly visible in these exposures,
but don't worry if they're not. The fun
begins by tapping the Enhance button.
The first time you do this each night
the app will pause for about a minute
while the Seestar shoots a half-dozen
dark calibration frames. The app then
displays an enhanced image of your
target that is continuously updated as

Sky & Telescope - March 2024

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