I set up
primarily to get the ST-4 figured out and properly adjust the accessory
flip mirror that came attached to the ST-4. Mirror has a reticle
that gets the guide star centered on the chip. Reticle and chip
needed to be realigned, since I changed the orientation of the mirror
in relation to the camera. The mirror also works to focus the
camera. Quite handy. Just need to get a 12V power adapter
to replace the transformer powering the ST-4 so I can plug it into a
deep cycle instead of using 120V or an inefficient inverter.
Worried
about flexure issues, I opted for mounting the imaging scope &
guidescope on a side by side adapter instead of piggy-back.
Shopped around and felt the ADM unit looked like the best option.
When it arrived yesterday and I opened the package, I was not
disappointed. What beautifully executed design and
machining. It is fairly heavy @ 4+ pounds, but I’m sure it won’t
be the source of any flexure.
Seeing was atrocious (no
surprise), but I did manage to get the ST-4 to calibrate. Took
setting the scintillation factor up to 10. Good seeing should be
around a 1 or 2, fair seeing about a 5. Recommendations for any
higher settings are to pack it in and go visual for the night.
Since this was a test session, the seeing quality wasn’t very important
– beyond getting at least decent tracking.
Tried various
exposure settings on the imaging camera, ranging from 4 to 12
minutes. The long ones were very overexposed, but I was looking
for star quality, not any usable data. Looks like the ST-4 will
be great. All exposures exhibited nice, round stars.
Control box showed the largest correction I observed over a two hour
period as 2 pixels on the guider’s tiny chip. Considering the
seeing, great results. No wonder the ST-4 has such a good
reputation.
Slewed over to M42 to take a stab at some
usable data. Nice to use something big & bright when testing
and under urban skies. The attached image is four frames of 4
minutes each, stacked and processed some in Nebulosity and
Photoshop. I took no darks or flats for this. Didn’t even
plan to post it while I was imaging. The core is blown out (no
surprise) and the wispy nebulosity at the lower right of the frame is
really faint, but the remaining parts of the image looked OK to
me. Even the Running Man came through the skyglow. Plan to
do it right from a dark location sometime in the near future.
Flats would have taken care of the vignetting. Cold enough that
the noise isn’t too terrible. However, the ST-4 cables became
quite stiff – particularly the one for the camera, which is not all
that pliable in the warm.
