Not only
is this trip #50, but it is the one-year anniversary of my being an
astronomer! Averaging nearly once a week
for bringing out the telescope is quite a feat.
I got new ethernet cables for the CGE mount
($15 on Amazon for two-foot shielded ones), and they worked like a charm! Telescope behaved properly all night. And I do mean all night – I was up till 5:30
AM. I ran the telescope on AC power, and
the dew heater on high on the battery, and the battery still didn’t
yellow-line. I had to run the hair dryer
twice though, even with the dew shield.
I’m glad the club has a few of those.
I didn’t start alignment and stuff
until after the camper stargaze, so at about 11 PM; I brought my C8 for
that. I pointed it back and forth
between Saturn and Mars, and delighted many children and adults with the
view. I love love love outreach. I also put my camera on the tripod and ran
around taking 4-8 second exposures of people looking through telescopes. The only really good one I got was a posed
one, since people tended to move. But it
was a fun experiment. I may try flashing
a light on them for part of the exposure so you can see both the people and the
Milky Way behind them. It was dark
enough to make out the Milky Way that night, finally.
I worked on getting the guidescope
working until about 1:30 AM. The hardest
part worked seamlessly – the camera talked to the computer, and the computer
talked to the mount. Even my test
commands worked right the first time.
However, I didn’t quite get the camera going. I took a set of darks, but
then the images were super grainy. And I
had no idea how to focus it, since defocused stars are too dim for cameras to
see, as I’ve discovered with my DSLR.
But Will told me he drew a line on the focusing tube for where it should
be, and that the noise will go away when it’s focused and has something to look
at. Then I just follow the procedure I
found online for getting PHD going – it’s got its own built-in calibration
process that measures how the telescope moves.
It takes about 5-10 minutes, according to the procedure. So next time, I think I can get everything
working. And I’ll not use the Barlow to
start with and see if the guiding is good enough despite the large difference
in focal length and pixel size.
Celestron 11-inch SCT
Celestron CGE mount
Orion ST-80 guide scope
Since I couldn’t quite get the guide
scope going, I shut it down and unplugged stuff, and just did unguided imaging
instead. I finally, finally got to image M20, the Trifid Nebula, on my own scope! And it came out great!
M20 Trifid Nebula, Nikon D3100 on my C11, f/6.3 focal reducer, new 2-inch T-adapter for my DSLR
I
enhanced the red a bit, since my DSLR isn’t IR-modified, but not too much. I might mess with stylizing my images
later. I'm still figuring out Photoshop. I’m pretty pleased! Hopefully with guiding I can get more of the
blue portion.
I was up late enough that I also did
a set on the Andromeda galaxy. This one
will need guiding to get the finer detail with longer exposures. I’m also planning on imaging it through the
guidescope itself in the near future.
Will showed me one of his images through it of M31, and you can easily
see M32 as well, there’s not really any color aberration (since it’s a doublet,
so two colors are corrected), and the coma is definitely visible but not
terrible. He says they make field
flatteners for small telescopes like that too.
So this still isn’t quite what I want, but it is very promising. It’s a large improvement over the C8, since
there’s no field rotation and I’ve got a larger FOV with the focal
reducer. I did have some severe problems
with either collimation, heat current, or non-orthogonality of the camera chip,
or something. I did collimate it, and stars looked good in
the eyepiece. I might need to collimate
it with the camera on instead, which will be more difficult because it’s
awkward to look through the viewfinder.
M31 Andromeda Galaxy, Nikon D3100 on my C11, f/6.3 focal reducer
88x30s, ISO-3200
Another
big improvement is I started using a 2-inch adapter for the camera, which
attaches to the rear cell and not the visual back, as opposed to the 1.25”
adapter I was using before. I think the
chip is bigger than the 1.25” adapter is.
It greatly reduced vignetting.
Below are the flats for comparison – left is the 1.25”, and right is the
2” adapter.
The
reason why the right image is blue is because I used the sky rather than the
LED spotlight on the battery to illuminate it.
I don’t think DSS cares whether the spectrum is white. The histogram still had a nice central
peak. Part of the reason why my Trifid
images came out so well I think is the less severe vignetting. Even though DSS can correct for it, you can’t
get the signal back that you lost in the first place.
Equipment fever is starting to hit
me hard! Can’t wait to save up for a
nice CCD for DSOs. Will definitely get
the QHY5 soon as a guide camera and planetary imager. Hopefully I can find one on sale on Astromart
or CloudyNights before the Saturn and Mars set.
Jupiter is already gone.