Tuesday, September 4, 2018

#159 - Sunday, September 2, 2018 - Just For Fun

Now that I've gotten fairly comfortable with astrophotography, it's been fun to experiment with different configurations, just to see what happens.  It's a lot more fun to do when the weather is nice, and it was quite warm on Sunday night - in the upper-60s and lower-70s.  Plus, since the forecast was dicey and the moon would be coming up after 1 AM, I didn't want to get too invested in trying to get a good image set.

Before the sun went down, I did have some time to pull out the astronomy club's solar scope again.  The sun has been very boring lately, and it was boring again!  It also appears that the transparency wasn't very good, although this wasn't terribly surprising given the presence of clouds.

Date: 2 September 2018
Object: Sun, in hydrogen alpha light (colorized)
Camera: ZWO ASI1600MM Pro
Telescope: Lunt LS60THA 60mm pressure-tuned (500mm FL)
Accessories: N/A
Mount: Celestron NexStar SE
Frames: 1761/3001
Exposure:  0.9 ms
ISO/Gain: 0
Stacking program: RegiStax 6

As it got dark, I decided to try and run two setups out at the observatory.  I've done this at star parties, but hadn't tried it yet at home.  I just bought a new QHY5L-II to use as a guide camera, particularly with the off-axis guider I've been testing out, which now means that I have two good guide cameras.  I also got my old laptop up and running for the Texas Star Party, and I just needed to install the Gemini ASCOM driver on it to use with the club's memorial scope.  For the other experiments I had planned that night, I needed the ZWO camera, so I put my Nikon D5300 DSLR onto the memorial scope instead of the ZWO for the first time in quite a while.  I had originally planned on doing that on Saturday night too, but forgot to bring along my T-adapter.  The memorial scope is a Vixen 140mm neo-achromat refractor, and since it's an achromat, the blue channel is fairly fuzzy and blown out-looking on the ZWO camera, so it's better to image with the DSLR on it anyway, where the effect is less severe.  I decided to image NGC 7380, the Wizard Nebula, after another astrophotographer in my club had recently posted a fantastic rendition of it.  He did his in narrowband, but I figured I'd give it a shot anyway.  It didn't come out great, but it's not bad either!  It would be much better without all the light pollution...
Date: 2 September 2018
Object: NGC 7380 Wizard Nebula
Camera: Nikon D5300
Telescope: Vixen na140ssf
Accessories: Astronomik CLS filter
Mount: Losmandy Gemini II
Guide scope: Celestron 102mm
Guide camera: QHY5
Subframes: 47x300s (3h55m)
Gain/ISO: ISO-1600
Stacking program: DeepSkyStacker 3.3.2
Stacking method (lights): Auto-adaptive weighted average
Darks: 31 (70F)
Biases: 21 (62F, had to borrow from another set...closest I could find...)
Flats: 0
Temperature: 68-72F

I forgot that I haven't built up a library of bias frames to go with my dark frames, and my house is 76F right now while it's 90F outside, so I had to dig around my image library to find biases that were close.  It's not usually that warm at night around here, so I couldn't find any.  It was already going to be a pretty noisy image anyway just because of the ambient temperature, so oh well.

While that setup was going, I decided to try out an idea from one of my fellow club members, Derek: mount my 45x70mm Oberwerk binoculars that I won two years ago onto an equatorial mount and attach an imaging camera to one eyepiece, and a guide camera to the other!  I figured that my ZWO's chip might be close enough to the front of the camera to achieve focus, so I decided to give it a shot.
I have created a monster!

Because the cloud situation was very uncertain this weekend, I didn't want to bring out a ton of my own gear, since it's a pain to move in and out of my second-story apartment.  So instead, I grabbed the Celestron Advanced GT mount from the club's scope garage, took off the Celestron C8 that was on it, and put my ADM Vixen-style dovetail on it with the binoculars attached via a 1/4-20 bolt.  The Oberwerk binoculars take standard 1.25" eyepieces, so I put 1.25" nosepieces on both my cameras and tightened them in like eyepieces.  Since my USB hub was in use in the memorial scope dome because the USB cable for my guide camera wasn't long enough to not pull my laptop off the table when the scope slewed, I utilized the ZWO ASI1600MM Pro camera's internal USB hub (it has two USB 2.0 ports on the back) to plug in my guide camera and the mount.  

Once it got darker, I turned on the camera and Polaris was in view as a bright, fat circle.  I rotated the eyepiece holder to focus, but unfortunately was not able to bring it in far enough - the binocs just didn't have enough back focus.  Darn!

It was suggested to me after I had already started tearing down that maybe a Barlow would bring it into focus.  But I already had my next task in mind, so I decided to table that for another day.

Next, since the sky had cleared off nicely, I dragged out the club's Celestron CGEM mount and loaded the club's Meade 127mm f/9 apochromatic refractor onto it.  I've suggested that we put the Meade into the memorial dome instead, since it's apo (meaning that all three wavelengths, red, green, and blue, are corrected, so the stars don't get those icky blue halos).  The club is also planning on putting a brand-new Celestron CGX-L in there to replace the Gemini mount, since it's been having alignment issues, and the hand controller doesn't work very well anymore (I've been mostly controlling it with my computer).  It's belt-driven, so periodic tracking error should be very minimal.  Exciting!  Can't wait to try it out.  Anyway, once it was loaded on, I got it balanced, and then realized that we had the declination axis flipped around the wrong way!  So I got some help to take it off and put it back on again.  Then I went to go attach my guide scope and cameras to it, and I realized that I didn't have my 2"-to-1.25" adapter so that I could attach my 1.25" filter wheel to it.  Luckily, the other club astrophotographer I mentioned earlier, John, was there, and I figured he might have the piece I needed.  Sure enough, he did, and I was finally able to get going.

Once I got everything balanced and connected, I slewed over to Vega to focus, and I had to add a 21mm spacer to the camera in order to get it far enough back to focus.  Luckily, adding length is easy, and I happened to have that spacer along because I've been needing to use it with the off-axis guider I've been testing.  Once that was done using the Bahtinov mask from the memorial scope, I loaded up SharpCap to do polar alignment.  Its polar alignment routine has worked really well for me since I started using it at the Texas Star Party, and it's super easy.  However, this time, it kept saying I wasn't rotating the scope after I had done the rotation!  I tried several times and went in both directions, but it still wasn't working.  So I gave up and used Celestron's All-Star polar alignment routine instead, which meant I had to align first.  The finderscope on this scope was kind of neat - it had a 90-degree-angled eyepiece on it that made it way easier to look in from all of the odd angles that equatorial mounts usually end up in.  However, finderscopes can be harder to use than something like a Telrad or red-dot finder, especially when the transparency is good and all the stars look bright, and it also wasn't aligned very well to the scope.  I had to fish around to figure out where the star needed to be in the finderscope in order to see it on my camera.  But I finally got it aligned, and then polar aligned, and then aligned again.  I took a frame on the Veil Nebula, but then it was already time to do a meridian flip.  It flipped around...and the camera hit the tripod leg!  That scope is sooooo long (1140mm focal length!).  This meant that the mount kept trying to slew when it was blocked from doing so, which meant I lost alignment.  After everything else that had already happened (including losing a spring in the grass from the dovetail tightener and searching around frantically in the grass for about five minutes), I threw up my hands and called it a night on that setup.  Some clouds were rolling through anyway!

...Buuuuuuut I don't usually give up that easy.  When the clouds cleared out, I really wanted to keep imaging, so I re-aligned (which was easier since I was already polar aligned, the camera was focused, and I knew the offset on the finderscope), and then slewed to the Andromeda Galaxy.  I had the exposure time on 1/2s, and a screen stretch on the image, and I could see the galaxy's core!  I love this camera so much. :D  The funny part was that I could see it on the QHY5L-II's screen on PHD as well, which was really cool.
That fuzzy splotch on the upper left part of the image is M31, the Andromeda Galaxy!

I took a series of 60s frames, but I realized when I was processing them on Monday that I was an idiot and forgot to re-focus the camera after it hit the tripod, which surely knocked it back a little bit.  It was just out of focus a little bit, so I didn't notice it when the images were going on my little tablet screen.  I stacked it anyway just to see how my first images through that scope would look, aside from the focus.

See those bloated stars?  Also don't mind the blown-out-looking core, this is a raw FITS image.

Despite the focus, it actually looks pretty all right...

Date: 2 September 2018
Object: M31 Andromeda Galaxy
Camera: ZWO ASI1600MM Pro
Telescope: Meade 127mm f/9 apo (club's)
Accessories: Astronomik L Type 2c 1.25" filter
Mount: Celestron CGEM
Guide scope: Orion 50mm mini-guider
Guide camera: QHY5L-II
Subframes: 22x60s (22m)
Gain/ISO: 139
Stacking program: DeepSkyStacker 3.3.2
Stacking method (lights): Auto-adaptive weighted average
Darks: 0
Biases: 0
Flats: 0
Temperature: -15C (chip), 68F ambient

Yeah that looks pretty cool!  High magnification for a refractor, but that can also be useful.  Can't wait to use it more.

After clouds covered up that part of the sky again, I was petering out, but still wanted to do more, since the Wizard Nebula was still unclouded, and I wanted to get as many DSLR images of that before the moon came up as I could.  Mars was burning bright in the south, the seeing looked steady since the stars weren't really twinkling, and I wanted to try using an IR-pass filter as the luminance channel, so I pulled out the club's Celestron 8-inch Schmidt-Cassegrain and put it back on its Celestron Advanced GT mount that I'd borrowed earlier for the binoculars.  I pointed it roughly north, and then had it slew to Mars.  I couldn't see it in the camera, so I grabbed a 32mm eyepiece.  The Telrad that was mounted on it was dead, so I grabbed the Telrad off of the club's 16-inch Dob, but since it was aligned to the Dob and not the C8, it could only get me close.  I still had to fish around for a few minutes until it finally popped into the telescope's FOV.  I got the camera focused, and then took a set of LRGB on it.  Then I grabbed my IR-pass filter.  This particular filter was given to me last year as part of a set of what I thought at the time were RGB filters, and I figured out that it was IR due to almost no light getting through it besides incandescent light bulbs in my house.  When I popped it out of the filter wheel it had come to me in, it said "IR72" on the side, and a weird "S" symbol. I eventually asked in Cloudy Nights what they were, and someone told me they were actually part of a Schuler photometric UBVRI filter set (ultraviolet, blue, visible, red, infrared), which explained why the colors were coming out so weirdly when I tried to use them with the SBIG ST-8300M I was borrowing!  So anyway, I have this IR-pass filter, and I've seen online that you can get better luminance frames for planetary imaging using an IR filter because IR light is less disturbed by atmospheric turbulence.  Blue suffers a lot from turbulence, and a luminance filter also passes blue.  I screwed it onto the nosepiece of the filter wheel, and then rotated the filter wheel so that the empty 5th hole was in view, and then re-focused the scope. Even though my camera has lower quantum efficiency in the IR part of the spectrum, it was still pretty bright.  

Stacked image of Mars in the IR channel, 611/2023 frames at 10 ms exposure time, gain 50.  It does look pretty sharp!  It's rotated about 90 degrees because it was south and I was using an equatorial mount.

I stacked the color channels in RegiStax, and then combined first the regular luminance channel with the RGB channels in RegiStax.  Sometimes it works, oftentimes it doesn't and I have to do it myself in Photoshop, but this time it worked.  It turned out kind of dim though, so I had to bump up the brightness.  Then I combined the RGB with the IR channel, which RegiStax didn't do right (even though I temporarily named it "L" since it needs that), so I had to align them myself in Photoshop.  It came out great!
Using a luminance filter as the luminance channel

Using an IR-pass filter as the luminance channel

Date: 2 September 2018
Object: Mars
Camera: ZWO ASI1600MM Pro
Telescope: Celestron C8 (club's)
Accessories: Astronomik LRGB Type 2c filters, IR72 photometric IR-pass filter
Mount: Celestron Advanced GT (club's)
Frames: L: 882/2004
IR: 611/2023
    R: 1014/2024
G: 649/2012
B: 799/2008
Exposure: L: 3 ms
  IR: 10 ms
  R: 5 ms
  G: 7 ms
  B: 25 ms
ISO/Gain: 50
Stacking program: RegiStax 6

An excellent experiment indeed!  I'll be using this filter more often...

All in all, it was a fun night!  I shut everything down around 2 AM because I was really tired, and I didn't want to sleep in too late, since I'm back at work on Tuesday.  I spent all Monday afternoon processing.  I used a bunch of different gear this weekend, most of it belonging to the astronomy club!  Let's see, I used...5 different telescopes on 3 different mounts! It was nice not lugging around a bunch of gear for a change.  I can't wait till I have my own backyard.

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