Monday, September 17, 2018

#161 - Saturday, September 15, 2018 - The Comet and the Supernova

Sometimes, going out to the observatory on a particular night is a bad idea.  And sometimes I do it anyway, despite my better judgment.  And sometimes it turns out to be a really good idea anyway!  On Saturday, I ran a 10k race early that morning, getting up at 5 AM.  The race started at 7:30 AM, and it was already in the lower 70s.  It stayed overcast during the race, but it was also muggy, so I was roasting hot by the end.  Despite my water-drinking efforts of the prior 24 hours, I still managed to become dehydrated, and I threw up in my friend's front yard, on her stairs, and then finally in her toilet.  Exhausted and sick, I made it home and took two 1-hour naps broken up by drinking water and eating some toast.

"Normal" people might have said, "Y'know, I probably shouldn't be out late tonight.  I should just go to bed."  But being normal is boring, so you bet your derriere I still went out to the observatory!

I was already still set up from Thursday night, so at least I didn't have to haul any gear around.  Just my DSLR, tripod, and bag with warm clothes, bug spray, and extra water and Gatorade.  I still had some hydrating to do.

I got out there around 8 PM, uncovered my Celestron AVX, Borg 76mm apochromatic refractor, and ZWO ASI1600MM Pro from underneath the TeleGizmos 365 cover I'd placed over the whole thing on Thursday night.  Once it got dark enough, I re-polar aligned (the setup is so lightweight, I was fairly certain that putting on and taking off the cover had moved it slightly) and then re-aligned.  However, while my western sky stars were showing up in the mount's initial guess easily, the eastern stars were not.  So I shut it off, re-polar aligned again, and then tried again.  The western stars were good, and the eastern ones were still a little ways off, and I had to use my finderscope to place them in the camera's FOV.  My target for the evening was continuing the Eastern Veil Nebula, NGC 6992.  I acquired the luminance frames on Thursday, so it was time for color frames.  I tried to use AstroTortilla to plate solve, but it was having trouble, so I gave up and tried to center the nebula myself.  I ended up a decent ways off of the luminance frames, unfortunately, although I still had the whole thing in the field.

Guiding was no better Saturday night than it was Thursday, unfortunately.  I tried guiding in just one direction again, and it helped a little, but not much, and then the dec axis took off and never came back.  As the night wore on, it just kept getting worse.  I did eventually re-focus the guide camera and re-calibrate guiding, but to no avail.

Finally, fellow club member John and I decided to pop open the dec casing to take a peak inside.  Sometimes, plastic shavings from the casing can get caught up in the gears.  We didn't see anything unusual though in the gears attached to the motor, but the worm gear was deeper inside the mount and would've required taking off a bunch of stuff to get to, so we ended up just putting it back together.  Further research is required.

In addition to that, I was having issues with my Hotech self-centering field flattener.  The 2-inch barrel at the end is just a little too fat to easily get into a 2-inch eyepiece holder, so I have to jam it into the one that screws into the Borg, and then take the Borg out of its ring clamps in order to screw the field flattener, filter wheel, and camera on as one piece because the filter wheel otherwise hits the dovetail bar and I can't actually screw it on.  Despite how hard it is to get into the eyepiece holder, it was still wiggling around, even though I had it tightened down.  Unfortunately, I didn't realize it was flopping around until much later in the evening.  

I'm starting to get suuuuuper frustrated with my gear.  I've put too much effort into this to be dealing with this crap!

Anyway, despite the problems, and the field flattener not flattening very well because it's too far from the camera with the filter wheel in between (I'm working on finding a male or female T-thread to 2-inch eyepiece holder so I can put it the correct distance from the camera), I managed to get at least a couple of color frames per channel that didn't have absolutely craptacular guiding.  I just reset the guide star about every 10 minutes, and was able to get some usable subframes.  

While processing the Veil Nebula on Sunday afternoon and seeing how bad my luminance frames really were, I decided to try something new to me - using my RGB frames together to create a synthetic luminance frame.  It's actually super easy, and the result was pretty good.

For this image, since I'm still practicing on better data with PixInsight, I used DeepSkyStacker to register and stack the RGB frames, and then I pulled each stacked R, G, and B frame into Photoshop and stretched and denoised them (using Deep Space Noise Reduction in Carboni's Tools).  I then combined them into one image (done by creating a new image, and copying and pasting each color image into the reg, green, and blue channels of the new image, respectively), and created a copy.  Next, I went to Image -> Mode -> Lab Color on the copy, clicked the Channels tab in Layers, and copied and pasted the Lightness channel into its down new document.  This is your synthetic luminance.  Then I copied that image on top of the RGB combined image, and set the blend mode as Luminosity, like I normally would for applying an L image.  Then I just went about processing from there, adjusting color balance and curves and saturation and the like.  (See this tutorial for a full walkthrough of my normal LRGB stacking and processing process with DeepSkyStacker and Photoshop).  It came out pretty well!  Plus I didn't have to worry about cropping out the big offset between my L image and the RGB images.  
Date: 15 September 2018
Object: NGC 6992 Eastern Veil Nebula
Camera: ZWO ASI1600MM Pro
Telescope: Borg 76ED
Accessories: Hotech SCA field flattener, Astronomik LRGB Type 2c 1.25" filters
Mount: Celestron AVX
Guide scope: Orion 50mm mini-guider
Guide camera: QHY5L-II 
Subframes: R: 8x180s (24m)
   G: 5x180s (15m)
   B: 6x180s (24m)
Gain/ISO: 139
Stacking program: 1: DeepSkyStacker
Stacking method (lights): Median kappa-sigma clipping (2,5)
Darks: 20
Biases: 20
Flats: 0
Temperature: -20C (chip), 66F (ambient)

Even though my Borg is an apo, which means it's supposed to not have chromatic aberration, I was getting some blue halos around the brighter stars.  They weren't nearly as pronounced as the ones I get on one of the club's telescopes, a Vixen 140mm neo-achromat refractor, and were easily correctable using Noel Carboni's Reduce Small/Large Blue Halos routines.  I also don't have any flat frames for this setup yet, since I have to pull out the drawtube on the Borg a little bit to reach focus, and it rotates freely, and I haven't really settled on the way I connect all the parts and pieces together to be able to draw reference marks so I can use the same flat frames every time.  So there's a bit of a glow in the middle.  But still, not bad for an hour's worth of data from a light-polluted location!  It's almost as good as the one I took of it on my DSLR from the Green Bank Star Quest last year, and that was doing 7-minute subframes from a very dark location!

The Eastern Veil Nebula is part of the larger Veil Nebula, or Cygnus Loop.  It's the remnant of a supernova that exploded 8,000 years ago, and now the nebula is 50 lightyears across!  It's approximately 1,470 lightyears away in the constellation Cygnus, the Swan, which is high overhead in the summer and early fall.  The original star was 20 times the mass of our sun.

By the time I got through all of the RGB frames, it was nearly 3 AM.  This was a lot later than I'd planned on staying out, but it's a lot easier to stay out late when you have friends there!  Fellow club member Bob was there as well, and my minion Miqaela, who had her Orion ST-80 on her Celestron AVX and was imaging the Heart Nebula and the Silver Dollar (Sculptor) Galaxy with her Nikon D5300.  John reminded us that Comet 21P/Giacobini-Zinner was rising by about that time, and I decided that I had to take this opportunity to catch it!  So I slewed over to its current location at the feet of Gemini, the Twins, just above star Propus.  Getting RGB images on a comet with a monochrome camera is not impossible, but is very difficult, especially with a manual filter wheel, so I decided just to take luminance monochrome images instead.  Because my guiding was so bad, I just took a bunch of 30-second frames, which were plenty to see this magnitude +7 comet.  In fact, I even aimed a pair of handheld binoculars that direction, and was just barely able to see its smudge!

Comets move with regard to the background stars, and move fairly quickly.  Thus, DeepSkyStacker has a few different comet stacking modes: align on the stars but streak the comet (standard stacking mode), align on the comet and streak the stars, or run registration and stacking twice and align both.  I did all three, but the align on the comet and the stars made for some really weird streaking artifacts in the background of the image, so I just went with the streaked stars, steady comet version.  Now, for added fun, DSS can't detect where the comet is located, so you have to do it yourself.  I had 50 frames, so I painstakingly selected the comet in every frame.  Luckily, it saves that information to the text file that contains the registration info for each frame, so you only have to do it once.  Using median kappa-sigma clipping made the stars get all weird and fuzzy and dim, but they looked much better when I used auto-adaptive weighted average as the stacking mode instead.
 Date: 15 September 2018
Object: Comet 21P/Giacobini-Zinner
Camera: ZWO ASI1600MM Pro
Telescope: Borg 76ED
Accessories: Astronomik L Type 2c 1.25" filter
Mount: Celestron AVX
Guide scope: Orion 50mm mini-guider
Guide camera: QHY5L-II
Subframes: 50x30s (25m)
Gain/ISO: 139
Stacking program: DeepSkyStacker
Stacking method (lights): Auto-adaptive weighted average
Darks: 20
Biases: 20
Flats: 0
Temperature: -20C (chip)

The gaps are a result of the many bad frames I had to delete.  I originally took 70.  Stupid mount and its tracking problems.

But anyways, you can see the tail!!  That is star Propus at the bottom.
Comet 21P was discovered by Michael Giacobini in December 1900 at the Nice Observatory in France, and Ernst Zinner observed its return 6.5 years later.  When I imaged it on Saturday night, it was 0.4 AU (astronomical units, or the Earth-Sun distance) from Earth, or 36.9 million miles.  

In addition to the above image, I also wanted to make a video.  To do that, I realized I could use PixInsight to apply the same processing to every image, and convert them all from FITS to JPEG after so I could make the video.  FITS is a special astronomy format that most everyday image editing programs don't support.

First, I needed to calibrate - subtract dark and bias frames to reduce noise.  I used the BathPreProcessing script for this, and saved out each file as a new image.  Next, I registered each frame to the frame the DeepSkyStacker gave the highest score to when I was processing the stacked image above so that the stars would be steady, and you could see the comet move through them without the jitter of the mount's crappy tracking.  Each of those aligned images were saved out.  Next, I imported one of the frames and applied a screen stretch using ScreenTransferFunction, and then applied that to HistogramTransformation to actually stretch the image.  I minimized that process and opened up a MultiScaleLinearTransform process to apply noise reduction (following the settings in the Light Vortex Astronomy tutorial I used recently on an Andromeda Galaxy image of mine), and then minimized that too.  After some Googling, I right-clicked on the background screen and clicked ImageContainer, and then opened all of my light frames in it.  I could only figure out how to apply one step at a time, so first I applied the HistogramTransformation process to stretch, and then re-imported all of the stretched images I saved out, and then applied the MultiScaleLinearTransform noise reduction.  Then I used the BatchFormatConversion script and converted all of the PixInsight-format images to 8-bit JPGs.  Finally, I used Time Lapse Movie Monkey to generate the video.  The slowest it would do was 10 frames per second, but that turned out to be fine.  So the video is only 5 seconds long (I need to make a repeating version next), but it's super cool!  
The video spans 33 minutes of real time.

Aaaaaaggghhhhhhh soooooo cooooooollllll!!!!!!!!

All the while I was imaging the Eastern Veil Nebula and Comet 21P, I had my DSLR on a tripod taking a series of 30s images facing north to make a star trails image.  They're super easy to create - I've got a tutorial in this post.  This is the longest one I think I've done, 5 hours and 20 minutes.  What you're seeing here is the rotation of the Earth on its axis that creates our day-night cycle.  The bright streak near the center of the vortex is Polaris, the North Star.  As you can see, it's not exactly on the North Celestial Pole, the center of that rotation, but it's quite close.  The pole is at the same altitude as your latitude, so if you live on the 40 N parallel, it will be 40 degrees above the horizon.  From the North Pole, it would be straight overhead.  From the equator, on the horizon.  In the southern hemisphere, they can see the South Celestial Pole, and use it for polar alignment instead.
Nikon D5300, 18-55mm lens at 18mm, f/3.5, ISO-800, 580x30s frames

There are several other interesting things going on here as well!  The long red streaks are airplanes.  The brightest one you can see made a few course corrections, hence the wobbliness.  The dome is lit up by red light from people arriving and leaving the observatory with their car lights on, and opening their cars to get stuff.  If you look closely a little ways above the dome, you can see a dimmer, shorter streak - this is a satellite.  In particular, it's an Iridium flare.  The Iridium constellation of communications satellites have orbits that cause them to glint the sun over to the darkened part of the Earth, and that glint lasts about two minutes as they move across the sky.  In this case, there are actually two streaks, since the aging satellites in that constellation are being replaced.  The second streak is the replacement.  I created another image with just the five frames that show the flare.

Satellites usually brighten and then darken as they move across the sky into the Earth's shadow, but Iridiums are far brighter, and for a shorter stretch of sky.  If you've ever looked up and happened to catch a bright light briefly appear in the sky and then fade out, it was probably an Iridium flare!  You can use the free cell phone app Heavens Above to track them.

I finally called it quits and packed up, and got home at 5 AM.  I realized that I had been awake for 24 hours!  (With the exception of the two hour-long naps I took that afternoon).  Whoopsie!  But I got such awesome images, it was totally worth it!



Saturday, September 15, 2018

#160 - Thursday, September 13, 2018 - Back to the Borg

The forecast said mostly clear with some possible high-altitude hazy junk, but I decided to go out anyway because I'm dying for a good deep-sky image.  It's been too long!  Plus, Saturday night was looking promising too, so I planned on leaving everything setup and covering it with my new TeleGizmos 365 cover that I bought after having to use a tarp for my C11 at the Texas Star Party.

But first, I had an outreach event at a local library to show patrons how to use one of the several library telescopes that my county's library system now own.  The program is growing in popularity, and they are nice little scopes!  They're Orion Starblast 4.5's, which are little Newtonians that sit on table-top alt-az mounts.  They're super easy to use, but provide some pretty nice views of the moon, planets, open clusters, some of the wider double stars, and some of the larger and brighter nebulae!  I've started recommending them to people when they ask what their first telescope should be for one of their kids.  Only five people came to the program despite the fantastically clear skies, but an outreach program is worth it for even only one.  This particular library was unwilling to schedule the program after library hours, so it ran 6:30 - 7:30, which meant it was still pretty bright daylight.  I showed everyone inside the parts and pieces of the scope, how it worked, and how to use it, and then I loaded up Stellarium on my laptop connected to a TV and pointed out some of the more prominent constellations and objects to look at from the suburbs.  Then we went outside, and luckily the crescent moon was bright enough to see, so they got to practice aiming the telescope, using the zoom eyepiece, and enjoying a view of the moon.
Smartphone photo of the moon through the Orion Starblast 4.5 library telescope, with the 8-24mm zoom eyepiece at 24mm.  Taken on my Samsung Galaxy S9.

After the program, I swung by a nearby Subway to pick up some dinner, but the people in front of me in line were ordering like a dozen sandwiches, and there was only one person working!  It took forever!  Then I missed a turn out to the observatory, which added another couple of minutes.  Then I made a stop myself on the side of a road near a corn field because the crescent moon, Jupiter, and Venus were making an absolutely beautiful trio in the western sky.  I didn't bring my tripod, but I did bring my DSLR, although trying to hold it steady for a half-second exposure was difficult.  None of the images I took really turned out as a result.  Some things you just have to savor the moment of instead.


I finally made it out to the observatory at 8:45, started building my rig at 8:55, which took about a half hour.  I was aligned, polar aligned, calibrated, and imaging by 9:55, which isn't bad, although I was hoping this setup would be faster.  I decided to not use the C8, since I'm still figuring out how to make it work on the AVX, and instead use the much lighter and easier Borg 76mm ED apo I have.  (Resistance is indeed futile!)  I have to use a field flattener with it, although it's not working as well as it could because of the extra distance between it and my camera's sensor thanks to the filter wheel.  (And before you ask, no I can't put it between the camera and filter wheel because while one side is indeed M42 threaded, the other side is just a 2-inch eyepiece barrel).

Borg 76mm ED apo mounted on my Celestron Advanced VX mount, with my ZWO ASI1600MM Pro camera attached, and guided by my QHY5L-II on an Orion 50mm mini-guider.

The sky was quite clear, but not as dark and clear as it was Labor Day weekend.  I decided to try the Wizard Nebula with this setup, but it became clear that it wouldn't be worth it from this Bortle 5 light-polluted location.  Even with a 5-minute subframe, I had to crank up the screen stretch on the subframe in order to barely see its core.
Single 300s subframe at unity gain on NGC 7380 Wizard Nebula from my ZWO ASI1600MM Pro on my Borg 76mm ED apo.

Since that wasn't going to work, I decided to hit up another high-flying summertime nebula: the Eastern Veil Nebula, which is part of a larger supernova remnant.  I've imaged it on the Borg before with my DSLR from Green Bank Star Quest, and it looked awesome. 

Unfortunately, the poor tracking in declination again reared its ugly head, even with the lightweight, wide field-of-view Borg and the itty bitty Orion 50mm guidescope.  My stars were getting pulled in the same direction over and over.  Even with only 3-minute subframes, it wasn't good.
Zoomed-in section near the middle of the frame.

Screencap of PHD2, the autoguiding program

I mean, it doesn't look that bad, but it sure was panning out in the images.  So I tried a recommendation I got on this past Sunday's Astro Imaging Channel session, which was to try turning off guiding in one of the dec directions to prevent the backlash from switching directions from happening.  The stars looked slightly better, but not much.  

 

I tried turning off dec guiding altogether as well, but then my stars just looked bloated in all directions instead of just one.  This shouldn't be happening with such a tiny scope!  😡 Maybe I should just take the other suggestion I got, which was to sell all my mounts and get an Astro-Physics 900 GTO or a Paramount!  

I went ahead and stacked the 35 luminance frames I gathered before I called it a night (since I had to be at work the next day, I stopped at 12:45 AM), and with careful processing to suppress the background light, it might work.
35x180s stacked luminance frames on the Eastern Veil Nebula.  Taken with my ZWO ASI1600MM Pro on my Borg 76mm ED apo at unity gain.

I would've gone for 5-minute subframes if the guiding wasn't already so bad.  Oh well, I'll try again on Saturday night with the RGB channels.


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

Details:
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.

#158 - Saturday, September 1, 2018 - Labor Day Weekend Labors

Labor Day weekend is always a fun camping weekend out at the observatory.  Several of the club members bring out their trailers and tents, and we barbecue brats and make s'mores if it's cloudy over the fire.  The forecast was showing that Friday and Saturday nights would be cloudy, and that Sunday had potential, but the moon is at third quarter, so we'd only get a few hours of astronomy in before the moon came up even if it was clear.  I brought out my camera bag and tablet just in case, but was expecting to be toasting marshmallows over the fire.

This weekend was also a good opportunity for me to try out my new tent, the Coleman Dark Room Sundome.  It's a black tent that was designed for festival-goers wanting to sleep in in the morning, or parents who want to put their kids to bed early while camping.  It's supposed to block 90% of the sunlight, and keep it cooler inside.  It's also perfect for astronomers at star parties!  I previously used my 1-person backpacker tent when I would camp at the observatory, and even though it was in the shade of one of the outbuildings, it was still tough to sleep in in the morning.  Plus, I couldn't fit an air mattress in it.  But the new tent worked great!
The underside of the rain fly is black too, and the lighter color on top helps deflect some of the heat and light.

It was fairly dark in the morning, and it wasn't too hot.  In combination with my sleeping mask and ear plugs, I was able to sleep in until at least 9:30 every morning this weekend.  If it were cooler, I probably could have slept longer, but it only got down to the upper 60s each night.  Sleeping on the air mattress was a lot nicer than my self-inflating sleeping pad.  And there was tons of space in the tent (it's a 4-person tent), so I had plenty of room to keep all of my clothes, shoes, and everything else dry.

It was cloudy in the evening as predicted, but the clouds weren't very thick, and several holes opened up in the sky.  Behind the clouds, we could see a lot of stars - transparency was really good!  

A frame from the timelapse I took.

Around 11:30, the clouds had pretty well cleared out, and the sky was gorgeous!  It was the most amount of stars I've seen out at the observatory in ages, due to this persistent high haze we've had for the past several weeks.  We could see the Milky Way pretty well (although, "pretty well" in these Bortle 5 skies means we can tell that there's a higher density of stars...almost just looks like a thick contrail...).  Since I'd brought my camera bag along, I decided to go ahead and open up the club's memorial scope dome and do some imaging!  I got my ZWO ASI1600MM Pro camera and my new QHY5L-II guide camera set up on the telescope, and I started imaging the Wizard Nebula, NGC 7380, after another astrophotographer in my club had recently produced an awesome image of it.  I got 15x300s frames on it before the moon came up.

I realized while I was processing it that since I recorded the lights in SharpCap instead of my usual Sequence Generator Pro, I forgot to switch the bit depth from 8-bit to 16-bit (I use 8-bit usually on SharpCap for when I do planets and the moon, since you don't need the bit depth).  So that bites.  I didn't want to go take a bunch of 8-bit dark frames, so I just decided to stack it without any calibration frames.  You can kind of see it...
Date: 1 September 2018
Object: NGC 7380 Wizard Nebula
Camera: ZWO ASI1600MM Pro
Telescope: Vixen 140mm neo-achromat
Accessories: Astronomik L Type 2c 1.25" filter
Mount: Losmandy Gemini II
Guide scope: Celestron 102mm
Guide camera: QHY5L-II
Subframes: 15x300s (1h15m)
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)

The moon was coming up soon, so I decided to do an experiment: short exposures, but tons of them, on my ZWO ASI1600MM Pro.  I've seen some incredible images of things like the Dumbbell Nebula and the Ring Nebula made from hundreds of exposures less than 30 seconds, sometimes as short as 1s.  I set the exposure time to 20s and the gain to 300 (which is the "lowest read noise" setting on my camera), and away it went!

I collected 246 of them before I packed up to go to bed at 2:30 AM.  When I processed them the following Monday, I painstakingly opened each of them to go through and delete the ones with tracking errors or that just looked mushy.  I was left with 220 after this.  I realized though that I didn't have any 20s darks, so I put the camera in my closet and took some dark frames.  Since it was so warm this weekend, I only took the light frames at -15C, which is reachable without having to use the fridge.  The camera body was pretty toasty afterwards, but it did reach -15C on the chip! 

Date: 1 September 2018
Object: M27 Dumbbell Nebula
Camera: ZWO ASI1600MM Pro
Telescope: Vixen 140mm f/5.7 neo-achromat
Accessories: Astronomik L Type 2c 1.25" filter
Mount: Losmandy Gemini II
Guide scope: Celestron 102mm
Guide camera: QHY5L-II
Subframes: 217x20s (1h12m20s)
Gain/ISO: 300
Stacking program: DeepSkyStacker
Stacking method (lights): 1: Auto-adaptive weighted average
Darks: 30
Biases: 0
Flats: 0
Temperature: -15C (chip)

So it didn't turn out as cool as I'd hoped.  This is about what I'd expect for any 20-second image.  It doesn't help that blue is not well-focused in this telescope.  Oh well, worth a shot!

Before I shut down for the night, I also grabbed a set of images on the nearly-third-quarter moon.  Beautiful as always!  Even when it ends my imaging sessions early...
Date: 1 September 2018
Object: Moon, third quarter
Camera: ZWO ASI1600MM Pro
Telescope: Vixen 140mm f/5.7 neo-achromat refractor
Accessories: Astronomik L Type 2c 1.25" filter
Mount: Losmandy Gemini II
Frames: L: 2327/3002
Exposure: L: 3 ms
ISO/Gain: 50