Sunday, January 21, 2018

#124 - Friday, January 19, 2018 - My Old Friend, DSLR

The forecast promised another clear, moonless night, but I also had an astronomy outreach event that night at the local museum where our club meets, so I brought my camera gear in the car and headed out to the observatory right after.  Well, almost right after - I always end up chatting with people for a while!  I got out there around 9:15 PM and got set up.  Kind of late, but hey, it's a Friday night, so I can sleep in the next morning.

I decided since it was going to be a short night to image with my DSLR.  I also wanted to see how processing the Pacman Nebula went so I could adjust exposure times if needed.  I didn't get to image the Christmas Tree Cluster/Cone Nebula region (NGC 2264) last winter, so I'm hoping to get a good image of it this winter!

After getting the field of view where I wanted it for the image (which took some effort since I couldn't see much of the nebula with all of the light pollution in the subframes), I hunkered down inside the warm room for a while.  My USB thermometer reported the temperature inside the dome as 29 degrees F, which felt quite warm after the single digits and teens we've been having, but there was a pretty stiff breeze.  I only opened the slit as far as I needed to to try and keep the wind out while I was in there.  After 20 minutes, I went to check on my images - everything was good.  After another 40 minutes, I went to check on things, and some thin, high clouds had rolled in!  I went back inside for another half hour to see if they would clear, but it only got worse, so I packed up and went home around 11:30 PM.

Christmas Tree Cluster/Cone Nebula region, single 300s frame on my Nikon D5300 through a 140mm neo-acrhomat Vixen refractor

Same, but with some thin, high clouds

I have found that it is much easier to see when clouds are in the picture on my DSLR images than my CCD images so far.  

One more thing I want to note is that if you look at the top image, you can see the mag 4.7 star 15 Monocerotis (this nebula is in the constellation Monoceros, "the unicorn," which is just east of Orion), which is the star I used to center the image where I wanted it.  Orientation can be hard to figure out between my cell phone app SkySafari and the camera's field of view, but luckily I could make out a brighter part of the nebula, so then I was able to adjust the position of 15 Mon to be far enough over that I would also catch the Cone Nebula.
If I rotate my phone (with auto-rotate turned off) to horizontal and then with the bottom up another 20 degrees or so, then it lines up with the image on my camera (judging by the star 15 Mon and the brightish section of nebula right next to it that you can see in the subframe.)

Looks like I'll just have to try again later...darn clouds!

#123 - Thursday, January 18, 2018 - Snowed In

After nearly a month of clouds, moon, and bitter cold, I finally made it back out to the observatory!  It has been frigid here lately, but I have acclimatized, so the 20s don't really feel that cold anymore.  I bundled up in my Under Armor base layer, fleece-lined sweat pants, sherpa fleece sweater, coat, fleece-lined hat, gloves, and thermal and wool blend socks tucked into snowboots, and trudged through the snow to the side dome at the observatory where the memorial telescope is I've been using.  The snow was a few inches deep, and someone stole our snow shovel a while back, so I cleared the entrance to the dome with my feet and yanked the swollen wooden door open.  After wrangling with the stiff extension cable that plugs into the main building and successfully opening the dome slit, I got all my gear setup.  I think this was the first time that setup went 100% smoothly - no guiding calibration issues, no hardware communication issues, and the telescope was still in perfect focus from my last trip!  My goal for the night: get green and blue channel images on the Pacman Nebula (NGC 281) so I can finally combine them with the red and luminance ones I took last month to create a color image!

Everything went swimmingly, so I went back inside the main building to the warm room and read a book and scrolled through Facebook, and went out to check on things and rotate the dome about every 40 minutes.  The Pacman Nebula is high and to the north, so I didn't need to rotate the dome as often as I do with something in the south - really only every hour or less, since there is more vertical motion than southward objects (and the slit is vertical).  

After taking 20x300s images on both the green and blue channels, I went home at around 11:45 PM.  I had to be at a middle school science fair I was judging before 8 AM, so I needed to get at least some sleep.  Also, yay for coffee!

The next day, when I copied the images over from my tablet to my desktop, I realized that while I had taken 5-minute subframes that night, my red frames were 10 minutes!  I had forgotten!  I'm told by experienced members of my club that I can just run an auto color-balance routine in Photoshop and it should be fine.  Hopefully there is actually enough light in the subframes to see anything - there already isn't much green or blue in the Pacman Nebula.

I've made some progress on attempting to process the image, but things aren't going so well - color gradients for dayz!  I'm enlisting the help of two of my club's more experienced astrophotographers, and I'll post an updated image here when I get there.  But so far, this is the mess I have created:
Object: NGC 281 Pacman Nebula
Camera: SBIG ST-8300M
Telescope: Vixen NA140ssf
Accessories: L frames: Astronomik CLS filter (2 inches), RGB frames: Astronomik RGB type 2c filters
Mount: Losmandy Gemini II
Guide scope: Celestron 102mm
Guide camera: QHY5
L: 20x600s (3h20m)
R: 9x600s (1h30m)
G: 20x300s (1h40m)
B: 20x300s (1h40m)
See on AstroBin

I'll keep working on it!  LRGB processing is way harder than processing my DSLR color images!
Once I start getting the process down, I'll write a dedicated post on how to process CCD camera LRGB images.  An exciting part in all this is that this is my "longest" image to date - 8.2 hours total of data!