June and July consistently delivered terrible weather for astronomy—here in the northwest US. There was one clear-ish night somewhere in the middle of the waves of thunderstorms, torrential rain, and general cloudiness, but on that one night we were close to a full moon and a few hours of clear skies amid the weeks of cloud that followed that night wasn’t worth the effort. So I waited for the next opportunity. Last night, August 11th, I set up the Sky-Watcher mount (EQ6-R Pro) with the William Optics SpaceCat and my new camera, which I bought in June.
Here's the result of my first imaging run with the ZWO ASI2600MM Pro mono camera, cooled to -10C, Antlia 3nm Hydrogen-alpha Pro Imaging filter (2 inch). 52 x 300-second sub-exposures with minimal calibration (bias & dark, no flat frames). The ASI2600 is built around the monochrome version of the Sony IMX571 APS-C sized sensor, and although you can get away with 36mm unmounted filters, I went all the way to 2 inch mounted narrowband filters. And not even a hint of vignetting. I didn't use flat frames when stacking. So, am I impressed with the ZWO ASI2600MM Pro? Oh yeah.
I started narrowband imaging about ten years ago with Atik mono CCD cameras, moved through a couple QHYs, and settled on the ZWO ASI1600MM Pro—the smaller, older generation of this ASI2600. I've been using the 1600 for four or five years, and it was time to upgrade. The 2600 has been out for a little while—I'm not new to this camera but I'm really glad I made the jump.
Target Notes: NGC 7822, Cederblad 214, SH2-171 (the brighter emission nebula core) as well as the star cluster Berkeley 59. There are several long chains and clumps of dark nebulae, including LDN 1268, 1275, Dob 3637, 3627, 3623, many more. Nestled in that large band of dark nebulae toward the bottom is the reflection nebula GN 23.56.1. The very small circle of gray at the top left, blending in but dimmer than the nearby stars, with less contrast, is the planetary nebula Abell 1 (PLN 119+6.1). Find all of this—the nebulae and star forming complex in Cepheus near the edge of Cassiopeia.
Click for full view:
It's a big jump from the ASI1600MM-Pro, going from a 4/3s size sensor to an APC-C at 26MP, which requires larger LRGB and narrowband filters. They're a bit pricier, but I have decided to go all the way to 2" mounted filters (or 50.4mm unmounted), anticipating a future jump to a full frame monochrome astro camera.
Sadr Region (Northeast) in Cygnus, with a batch of HII regions and dark nebulae, including IC 1318A, LBN 251, DWB 82 (all refer to the large, bright triangular mass at the top right), scattered lumps of dark nebula, including LDN 894, 892, 891, Dobashi 2429, 2468, 2449, et. al. This is probably it for a little while. We have five or six days of rain storms headed our way, and a waxing moon right along with it.
Setting up two refractors, the William Optics GT81 (right) and William Optics SpaceCat 51 (left). I'm running monochrome with 3nm filters on the SpaceCat and RGB color on the GT81. It's beautiful out there now, but into the evening the forecast is calling for a solid cloud cover. I'll be ready if there's a decent break in the clouds!
The Cygnus Wall in NGC 7000 (Caldwell 20), the North America Nebula in the constellation Cygnus. These clouds of molecular hydrogen and oxygen are about 2600 lightyears away from us, and to provide some scale, this frame is about a hundred lightyears from one side to the other, or about 600 trillion miles or 950 trillion kilometers. Notes: stars removed with StarNet2 to highlight the softer wisps of dark nebulae scattered in front of the bright emission nebula beyond.
A star trails view of the NCP (North Celestial Pole) from my backyard, five hours of 15-second exposures stacked together to show the Earth's rotation. That star in the middle is the North Star, Polaris, the star at the end of the handle in the Little Dipper asterism. Polaris is very close to the NCP, only 4 degrees off the actual point in space that marks our planet's North Celestial Pole. Basically, if you're standing in a fixed position on the surface (say, in coastal New Hampshire at around 43° latitude) and draw an imaginary line along Earth's axis of rotation, out into space, until you reach a single point in space--that's the celestial pole, and from your perspective, all stars will rotate around that point. In the southern hemisphere, looking south, you have the SCP, South Celestial Pole, which doesn't have a bright star in close proximity--so imagine this image without that bright point of light in the center.
What is also interesting in this image is that stars have color. Blue stars "burn" hotter and faster, redder stars are generally cooler and longer-lived. Our star, the Sun, is somewhere between, a medium-sized main sequence star about halfway through its 11-billion-ish year lifespan.
Notes: 1104 x 15-second exposures, Sony A7s, Irix 15mm f/2.4 lens, stacked in StarStax.
Dark nebulae B312, B313, and planetary nebulae PN G016.3-02.3 and M1-46 in Scutum. 36 x 240-second Ha subs with the William Optics GT 81 and ZWO ASI1600MM-Pro monochrome camera.
LDN 935, 933 (dark nebulae), the "Gulf of Mexico" region of NGC 7000, the North America Nebula in Cygnus.
Dark nebula Dobashi 2961, et al. below the North America Nebula, 3 nanometer hydrogen-alpha:
Atlas and Catalog of Dark Clouds Based on the 2 Micron All Sky Survey
Kazuhito Dobashi, Publications of the Astronomical Society of Japan, Volume 63, Issue sp1, 25 January 2011, Pages S1–S362, https://doi.org/10.1093/pasj/63.sp1.S1