SALTWATER WITCH ASTRONOMY

Messier 5 and 5 Serpentis

The M5 globular cluster in the constellation Serpens (NGC 5904) might be the oldest globular cluster in our galaxy, somewhere around 13 billion years old, with the Milky Way itself almost as old as the universe at 13.61 billion years, forming just a few hundred million years after the Big Bang. M5 is about 27,000 lightyears away in the galactic halo, and is one of the largest clusters, with a diameter of about 165 lightyears. Imaging notes: 60 x 60-second subs with the ZWO ASI071MC cooled to -10C and the 800mm FL newtonian scope.

Take a closer look at the variable double star, 5 Serpentis, lower right with the diffraction spikes (the spikes are an artifact of some reflector telescopes, like the Hubble Space Telescope). If you look closely, you can see both stars, 5 Serpentis A is the larger of the two, with 5 Serpentis B just visible at the lower left of the main star. The main star (5 Serpentis A) is a large F-type main-sequence star, that has been fusing hydrogen like mad, has used most of it up, and is headed toward a red giant phase. Its companion, 5 Serpentis B, much smaller, has recently been estimated to have an orbital period of 3,371 years.

Posted May 11, 2023

What a Cluster!

From last night's imaging session: the massive star cluster, M13, NGC 6205, the Hercules Globular Cluster, is made up of hundreds of thousands of stars. Like most globular clusters, M13 is not found within the disk and spiral arm structures of the galaxy, but in the galactic halo, the outer spherical shape of the galaxy, above and below the galactic plane. M13 is about 145 lightyears in diameter. Notice the spiral galaxy on the lower left side--that's NGC 6207 (about 30 million lightyears away), with the far more distant galaxy IC 4617 (489 million LY!), just a tiny, faint smear between NGC6207 and the M13 globular cluster. Imaging notes: 800mm f/4 newtonian, ZWO ASI071MC cooled to -10C, 60 x 120-second exposures stacked in DSS.

Posted May 10, 2023

Messing around with Messier in Infrared

We finally had several hours of clear night sky--not spectacular, but I'll take what I can get this time of year. That whole “April showers bring May flowers” thing really applies to this region of the planet. I think we’ve had four or five full clear nights in the last couple months--and I can’t remember multiple clear days in a row, but I am looking forward to more opportunities to capture the night skies soon--early summer through the winter.

One of the paths I’m currently on is to be more productive--in very concrete terms. I simply want to produce more imaging data per night than I have before. One way to do this is to upgrade equipment and pile on new devices, which translates into an EQ mount with more capacity and another scope and camera to double the exposure time. In other words, spend more money, which I don’t want to do.

Another option is to improve the efficiency of my current setup and systems. This is where I’m presently spending my time and effort, squeezing out 5-10 minutes per hour I was losing with slower hardware and application workflows (per image download times, auto-focus and plate-solving routines, etc). I will test out NINA (https://nighttime-imaging.eu) at some point, because I’ve heard great things about its speed. I’m currently using Sequence Generator Pro 3 with my narrowband refractor setup (William Optics GT81, Moonlite Focuser, ZWO ASI1600MM-Pro mono, and ASI120MM-Mini Guide-cam), and with a few exceptions and idiosyncrasies, which often turn out to be ASCOM or device-specific weirdness, not an SGP problem, things are going smoothly.

I have been working through a couple different configurations of equipment, automation systems, and application workflows, mostly focused on building a narrowband setup with two cables--USB3 and a single 12vdc 10 amp line. For now, I’m using Windows 10 on a fanless Celeron-based system, which easily handles the processing load during capture and plate-solving. On the scope itself I have the Moonlite Focuser controller, a powered USB 3 hub, and all power, environment, and dew control functions managed through a Pegasus Astro Pocket Powerbox.

I ran my first in-depth test of this system last night, jumping all over the sky east of the meridian, taking several 1-minute subs of M3, M10, M12, M13, M51, and NGC 6826 (blinking planetary nebula in Cygnus). I have to say, my impression of SGP has not changed. I already had a high opinion of it, and coming back to it for version 3 has been fun and exciting--and more importantly, productive. I was skipping all over the sky last night, pulling up the Framing and Mosaic wizard half a dozen times, and appending new targets to the sequence. I would have kept going after midnight, but the clouds rolled in and shut the show down.

Near-IR filter notes--something to consider if you’re guiding off-axis: I’m using Astronomik 1.25” narrowband filters (Ha, OIII, SII) in this ZWO EFW, but I also have an Optolong IR 685nm longpass filter installed in the 5th place. I ran into a slight issue with off-axis guiding because the IR filter’s focal offset with the Astronomik’s is so great that it throws off the focus of guide camera. I have to plan to do any near-IR exposures at the end of any sequence because this forces me to adjust the focus in PHD2 for the ZWO ASI120MM.

Here are a few shots from last night, using the Optolong 685nm longpass filter.

Whirlpool Galaxy (M51) in near-Infrared, WIlliam Optics GT81, ZWO ASI1600MM-Pro mono, 685nm Near-IR longpass filter. M51 is around 23 million lightyears away from us in the constellation Canes Venatici. It’s a tiny view of the galaxies, but I’m impressed with the trailing gas and dust that IR managed to capture.

M10 (NGC 6254) is a globular cluster of stars about 14,000 lightyears away in the constellation of Ophiuchus. 4 x 60 second subs in near-Infrared, William Optics GT81, ZWO ASI1600MM-Pro mono, 685nm Near-IR longpass filter. In IR the stars are really distinct in the cluster, and I want to come back with RGB and use the IR frames for luminance, and see how that looks.