Greg Marshall
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gbmbuku.bsky.social
Greg Marshall
@gbmbuku.bsky.social
20 followers 7 following 29 posts
Retired electronics engineer, now enjoying making music and astrophotography.
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Shouldn't everyone be anti-fascist? The name "antifa" may mean a little bit more than that, but it's not an organization, so how can it be a terrorist organization?
September 19, 2025 at 1:32 AM
gbmbuku.bsky.social
Wachured Observatory Goes Solar
I just finished converting the observatory power system to all solar. I had been powering it with a long extension cord to the house, but this was problematic for several reasons. Most importantly, we get a lot of electrical storms here, and a long wire across the ground will pick up a lot of energy. This resulted in a damaged circuit board in my mount, which cost $800 to replace. I bought a pair of 100W panels for $125 (which seems to me a very good price), constructed the wooden frame with pressure-treated lumber, and connected it to a "solar generator", which produces AC power for everything in the observatory. The DC power lines feed through the wall of the observatory via "bulkhead" connectors to maintain the somewhat water-tight structure. The solar generator can be easily disconnected, so that I can take it to remote sites and star parties (I have a more portable 200W solar panel for that case). One of the puzzles I had to solve in this project was what angle to tilt the panels. The optimal angle for power production varies through the year, but since I didn't want to make it adjustable, the angle is a compromise between Summer and Winter optimization, which came out to 35 degrees below horizontal. That might not be the smartest solution because I will need more power in the Winter, since the nights are longer, and the equipment will be on for longer periods. On the other hand, the solar panels on the roof of the house are tilted to just 10 degrees. That is the standard here for flat roofs, with the objective being to keep them low enough that they are not visible from the ground.
August 16, 2025 at 2:32 PM
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New Guitar Day
An Epiphone SG Muse in Pearl White joins it's big brother, the Epiphone Sheraton (wine red). Play is very similar between the two, and with selectable pickups and split-coil switch it's easy to get a wide range of sounds out of either. So why a new guitar? Mainly because it's much lighter than the Sheraton. But in both cases they look much better than they sound with me playing!
August 7, 2025 at 7:47 PM
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The Pinwheel Galaxy (M101)
Over my recent trip to Washington and Oregon (including the Oregon Star Party) the skies were cloudy at least half the time, and this time of year the nights are REALLY short up there. I like to collect a lot of photons from each target, so in this case I completed just 1 image; M101, the Pinwheel Galaxy. This was done with a William Optics FLT-132 telescope (with 0.8X reducer) and QHY268m camera, which means that the field of view is much larger than most galaxies, so I chose the biggest one (after Andromeda). It would have been somewhat larger if I had not used the 0.8X reducer, but this device also provide field flattening, which is essential. After discarding numerous bad frames, this image includes about 12 hours of exposure (over 5 nights). M101 is about 21 million lightyears from Earth, in the constellation Ursa Major. Its diameter is more than double that of the Milky Way at 250,000 lightyears, and it contains about 1 trillion stars.
July 8, 2025 at 4:06 AM
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xkcd.com/3081/
PhD Timeline
xkcd.com
April 25, 2025 at 7:18 PM
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The Flaming Star Nebula
(Recently captured from my home observatory near Santa Fe, NM)
The Flaming Star (IC 405) is an emission/reflection nebula in the constellation Auriga, about 1500 lightyears from Earth. This image was captured with narrowband filters, so it does not show a significant amount of the reflection nebulosity, which consists of some faint blue wisps near the brightest part of the emission nebula. A little over 10 hours of exposure was used. This time of year (and from my location) it is a good target for only a couple of hours, so this was done over 5 nights.
April 15, 2025 at 8:38 PM
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Perfect!

xkcd.com/3073/
Tariffs
xkcd.com
April 8, 2025 at 2:39 AM
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First Year of Solar Power

Having installed roof-top solar panels a year ago, we can now summarize the results:

- 13.43 Megawatt-Hours generated (avg. 1.12 MWh/month)
- 10.5 tons of CO2 emissions saved
- Equivalent of 24,000 miles driven by an average car
- Over 1 MWh "banked" for future use
April 5, 2025 at 12:18 AM
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The latest addition to my guitar collection: A "Cigar Box Guitar" made by my friend, Dave Lowell, with a couple of my astrophotos on the top. It has a magnetic pickup under the top surface, to show the photo as completely as possible.
March 31, 2025 at 3:46 PM
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The Jellyfish Nebula (and friends)
The Jellyfish Nebula (yellowish object in the lower right) is cataloged as IC 443 and Sh2-248. It is a supernova remnant (SNR), probably formed 30,000 to 35,000 years ago. It's about 5,000 lightyears from Earth, in the constellation Gemini. This image was captured in my backyard observatory using a Stellarvue SVX80T telescope and QHY268m camera with narrowband filters. The color assignment is simple: Red is hydrogen, green is sulfur, and blue is oxygen. Yellow (red plus green) indicates both hydrogen and sulfur are present. It seems like there is very little blue (oxygen), but there is some around the edge of the jellyfish. It also "modulates" the color somewhat in the red nebula on the left.
March 13, 2025 at 9:09 PM
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Crops from the Cone & Foxfur Image.
This close-up view of the Cone and Foxfur nebulae is a crop from the photo I posted earlier, showing just the 2 named nebulae. The Cone is center left and the Foxfur is just right of center (look for the eyes and nose). This close-up of the Boar's Head is cropped from the Cone & Foxfur photo I posted earlier. I'm hoping to get people to start calling this the Boar's Head Nebula, so please share it! P.S. If you look closely at the right center you might see a pink curl - the boar's tail, maybe?
March 3, 2025 at 7:49 PM
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Cone & Foxfur Nebulae - and More!
The Cone Nebula is the small cone-shaped object at center left. The Foxfur is a little harder to pick out, but it at the right hand end of the pink/orange region near the center. What was totally unexpected (by me, anyway) is that dark nebulosity to the right and slightly below center, and looking VERY much like a boar's head! As far as I can tell this has never been cataloged or named, although a small portion of it is cataloged as a Barnard's Dark Nebula. The bright spot in the lower left is Hubble's Variable Nebula. In this version the stars have been removed. This version includes the stars.
March 3, 2025 at 1:19 AM
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The Moon, Venus, and Cholla. From my backyard this evening.
March 2, 2025 at 3:10 AM
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March 1, 2025 at 3:56 AM
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The Seagull Nebula (IC 2177). Captured from my home, south of Santa Fe, New Mexico.
Located on the border between constellations Monoceros and Canis Major, about 3,600 light-years from Earth. While it does look like a bird to me, that mouth definitely suggests a raptor, not a seagull. And it appears that he is about to throw a fireball at something! This is a narrowband, false color image, captured with a small telescope of just 80mm aperture. It is made up from 205 exposures of 4 minutes each, for a total of 13.7 hours.
February 27, 2025 at 5:19 PM
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From my friend, Chris Harrell:
www.youtube.com/watch?v=Cd9C...

Please share!
Stop the Coup! - Chris Harrell
YouTube video by Chris L Harrell
www.youtube.com
February 22, 2025 at 12:20 AM
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The Rosette Nebula in Monoceros, from my backyard observatory.
I just finished capturing images last night and did a quick processing of it this morning. This is only about 10 hours of exposure, but it's a fairly bright nebula, so a lot of detail is already apparent. The Rosette is cataloged as Caldwell 49, and contains several small star clusters that are in the NGC catalog. Both the nebula and clusters are about 5,000 lightyears from Earth. This is a narrowband image, captured with H-alpha, Sulfur-II, and Oxygen-III spectral line filters. These filters tend to suppress the star brightness, and they are further suppressed by separating the star image and processing it separately. When viewed directly through a telescope you would see a lot of stars and very little nebulosity. In particular, our eyes don't see dim red very well, so only the blue-green portion (which corresponds to oxygen) would be seen.
February 8, 2025 at 6:16 PM
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Re-processed version of Thor's Helmet Nebula.
I recently got a new and much faster computer, so to test it out I re-processed this image of the Thor's Helmet Nebula. This is actually a simpler version, but the main difference (aside from removing all the stars) is that the faster computer allowed me to play with the settings in the sharpening module (RC-astro's BlurXTerminator) to optimize it. Although there's little detail in the surrounding red area, this is probably accurate, since the nebula is surrounded by a diffuse cloud of hydrogen.
February 5, 2025 at 11:32 PM
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A beautiful sunset, with the Moon and Venus above.
February 2, 2025 at 1:35 AM
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Thor's Helmet. Surprisingly, I've never shot this target before.
Thor's Helmet is an emission nebula in the Canis Major constellation. It is about 12,000 lightyears from Earth. It was likely formed by the extremely hot Wolf-Rayet star WR7 in a pre-supernova event. The image is the result of roughly 10 hours of exposure using 3nm narrowband filters, processed in PixInsight and Photoshop.
January 30, 2025 at 9:19 PM
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Latest astrophoto: IC 63, The Ghost of Cassiopeia
IC 63 is an H-II region located near the star Gamma Cassiopeia (the bright star in the upper left). It is about 10,500 lightyears from Earth, and is also cataloged as Sh2-185. While they are often photographed together, IC 63 is really the bright region near the center, while the structure to the left is IC 59. I've been working on this image for a long time, mostly due to technical issues, including a camera change and then a problem with light leaks. It also didn't help that I've been away from astrophotography for a while. This crop from the original image isolates IC63. The stars have been removed, and contrast is adjusted.
January 24, 2025 at 9:07 PM
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Modern take on Woody Guthrie's guitar.
January 20, 2025 at 7:51 PM