December 11, 2024

Posts Comments

You are here: Home / 2020 / Archives for December 2020

Archives for December 2020

M81 & 82 – Spiral Galaxies in Ursa Major

December 6, 2020 by
M81 & 82 – Spiral Galaxies in Ursa Major

Telescope: Meade SN10 at f/4, Orion Atlas EQ-G

Camera: ZWO ASI071MC Pro, -10C; Gain: 200

Filter: 2” Orion Imaging Skyglow filter

Guide scope: Williams Optics 50mm, Meade DSI Pro II, PHD

Exposure: 16x240sec saved as FITS

Darks: 32x240sec saved as FITS

Flats: 32x10sec using an LED tracing tablet with 3 layers of muslin

Average Light Pollution: Red zone, fair transparency

Lensed Sky Quality Meter: 18.4 mag/arc-sec^2

Stacking: Mean with a 2-sigma clip.

White Balance: Nebulosity Automatic

Software: Nebulosity, Deep Sky Stacker, Photoshop

This is M81 (bottom) and M82 (top), two bright spiral galaxies lying about 12 million light years away in Ursa Major. At present, these two galaxies are about 150,000 light years apart, though a few hundred million years ago the two passed very close to each other. The dark dust lane slashing across M82 is one result of this close encounter with M81 as are the blue star formation regions in M81. If you look to the left of M81 you can just barely glimpse the irregular galaxy UGC 5336. This little ghost is approximately 13 million light years away and is only about 9200 light years across.

Filed Under: Deepsky Imaging

M82 – Spiral Galaxy in Ursa Major

December 6, 2020 by
M82 – Spiral Galaxy in Ursa Major

Telescope: Astro-Tech 8” f/8 Ritchey-Chretien, Orion Atlas EQ-G

Camera: ZWO ASI294MC Pro, 0C, Gain 200

Filter: 2” Orion Imaging Skyglow Filter

Guide scope: Astro-Tech 60mm, Meade DSI Pro II, PHD

Exposure: 57x240sec, saved as FITS

Darks: 32x240s, saved as FITS

Flats: 32×0.25sec, sky flats taken at dusk

Average Light Pollution: Red zone, Bortle 8, poor transparency, bright moonlight

Lensed Sky Quality Meter: 17.6 mag/arc-sec^2

Stacking: Mean with a 2-sigma clip.

White Balance: Nebulosity Automatic

Software: Nebulosity, Deep Sky Stacker, Photoshop

M82 is a close company to the nearby spiral galaxy M81 which is located about ½ degree to the south. These two form an interacting pair and M82 bears the scars of a close encounter with M82 about 100 million years ago. The dark dust lanes that cut across the central region of the galaxy are very distinctive and are easily visible in modest telescopes. M82 was originally classified as an irregular galaxy, but detailed studies had shown that it is actually a spiral seen nearly edge-on.

Filed Under: Deepsky Imaging

Copernicus – 11/28/2020, 21h30m EST

December 6, 2020 by

Telescope: Celestron C9.25 @ f/20, Orion Atlas EQ-G

Camera: ZWO ASI294MC, Gain 285

Filter: Highpoint Scientific IR Filter

Exposure: 64×0.01sec, saved as FITS

Seeing: fair, 3/5

White Balance: Nebulosity Automatic

Software: Sharpcap Pro, Nebulosity, Registax, Photoshop

Copernicus and its rays is one of the most beautiful structures on the lunar nearside and can even be seen with the naked eye as a bright region near the center of Oceanus Procellarum. The crater is 57 miles across, but only about 2.4 miles deep, making it about the same profile as a dinner plate. High resolution images of craterlets that radiate out from Copernicus reveal fishbone-like dunes that formed from the interference pattern of shockwaves that were generated during the formation of these crater chains some 800 million years ago. You can also see terraces circling the walls of Copernicus that formed as the terrain subsided after the impact. The smooth flat floor of the crater was selected as a landing site for one of the canceled Apollo 18-20 missions.  This image is one of a set taken as part of the first-light check-out of the new to me C9.25.

Filed Under: Solar System Imaging

Fixing Mirror Flop

December 5, 2020 by

I just finished putting my new to me C9.25 back together. It had the classic symptom of not holding collimation and not holding focus after slewing. I suspect that this scope has never been taken apart as there were spots of fungus on the inside of the corrector and the corrector was really stuck! I marked its orientation, sprayed around the edge with Windex, and carefully worked it loose. I reached down inside and engaged a wooden dowel with one of the spanner holes in the lock ring a nudged it. Sure enough, it was completely loose. I could turn it about 1/2 rotation without any resistance. Just a tad more, and it was snug. While I had it open I removed a few tiny spots off of the primary and secondary with lens tissues .(I _hate_ touching the mirrors, but sometimes you get lucky) The secondary also have a bit of fungus, now clean.  I carefully cleaned the inside of the corrector with Windex followed by breath and lens tissues. Before closing the tube I inverted it and used a puffer bulb to blow the dust out, and then carefully lowered the corrector back in place. I didn’t like the original tiny spacers, so I cut ribbons of black construction paper and layered them evenly around the corrector until the gap was full (about 5 layers total all the way around). I remounted the rail, reinstalled the finder, touched up the paint, and now it’s ready for testing. I love reconditioning these old scopes!

So far I’m 3 for 3 finding loose lock rings. Tomorrow I’m going to open up a 12″ that’s showing the same symptom. Gotta do something while it’s cloudy.

Filed Under: Equipment
« Previous Page