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comment by francopoli
francopoli  ·  54 days ago  ·  link  ·    ·  parent  ·  post: Pubski: August 1,2018

Mars opposition July 28. IR filter, shit atmosphere, but still worth posting. Now seriously looking forward to October 2020 for a better apparition for us in the Northern Hemisphere.




kleinbl00  ·  54 days ago  ·  link  ·  

Dayum, son, that's nice! What are you using for a scope again? What's the CCD? Is that a composite? And what caused the red bar on the right?

francopoli  ·  54 days ago  ·  link  ·  

The scope is my "grab and go" Celestron 8SE. Camera is a modified security camera and the bar on the side is solely my shitty photo editing ability. The IR filter is a limiting filter centered on 685nm, or just outside normal human vision in the far red, which helps pull surface detail. I got this filter because the other use of this particular wavelength is Uranus and Neptune, two planets I have never been able to image.

The way you do planetary imaging is to take thousands if not tens of thousands of images, usually in an AVI file (I use the SER format as the write to disk is faster and less conversion bullshit). Then you use a 'stacking' software that looks at these images and throws out 60-70% of them, either they are too blurry, the planet is not in the frame, a batch of bad air make everything out of focus, etc. Once you have a "stacked" image, it is blurry and fuzzy looking. Take that into a specialized software to sharpen and denoise the image until you get something like the above.

I need a better telescope and mount for imaging. I also need to suck it up and buy a software package dedicated to astronomy imaging. You will note that Registax has not been updated in a decade, and although it works wonders, it is starting to show its age. I also want to swap out the drive in the laptop for an SSD to get more frames. Most of the images were taken at an exposure of 2ms; for Saturn which is 10x dimmer, the exposures are in the 20ms range and that limits the framerate you can capture.

I'm getting better at the processing and cleaning up, but now I am gear limited. Once I take care of some personal stuff I am looking at a Mak-Newt (er Maksutov-Newtonian) telescope to really do some planetary stuff. The other option is a Maksutov-Cassegrain which for the planets are about the best game in town at the affordable level. If all goes very well, I am looking into the 12" and 14" Meade Schmidt-Cassegrain so I can progress from planets to deep sky and utilize the club observatory's extra pier.

Once I get all the life bullshit settled I am looking at using some fun money, to the tune of about $4K for the optics, $1K for the focuser, $5K for the mount and electronic upgrades. I can use my existing cameras and other gear, then start saving up for the 100TB RAID upgrade, the next camera ($2K) etc.

The running gag is is you don't want your kids on drugs, get them into astrophotography as they won't have any money for anything else. As a camera guy yourself, I bet you can relate.

francopoli  ·  54 days ago  ·  link  ·  

Since you will appreciate this, here is the "stacked" image from above with no processing. Lots of sharpening and denoising later you get the first image. The bar is probably random noise in the CMOS that the sharpening picked up when I toyed with the historgram and did not notice on the screen for whatever reason and need to go back and black out in GIMP when I get a few.

kleinbl00  ·  54 days ago  ·  link  ·  

You forget - I was an astronomy nerd once, too. 10" Coulter Optical with Telrad, a couple plossls and a handful of planetary filters. Sketchbook full of Messier objects, the whole nine yards. Then I moved to Puget Sound and suddenly there were five (5) Plieades.

I'm guessing you need 170FPS because of the stacking? Now explain to me the differences between your twitchy little security camera and Monsters of the Deep like this. I mean yeah. The sensor is eight times as big. The resolution is half, though. And holy fuck you can now buy adaptive optics for under a grand.

Somewhere I've got a picture of me next to a 25" Obsession. Once I started living near the ocean, though, that became a serious waste of money even to dream about.

I pointed this place out to my wife once. She said "eh."

francopoli  ·  54 days ago  ·  link  ·  

Looking at M13 through a 25" Obsession is a religious experience. Looking at something like the Cat's Eye Nebula through a 32" telescope will make you curse your life choices.

The fast frame rate is to try to get as many not-blurry images as you can. The people in Australia , where Mars is 80° above he horizon are able to take longer exposures, grabbing more detail. Longer meaning 4-5ms versus my 2.

The camera you link is designed for wide field deep sky. Note that the pixel size on that baby is 13 microns. that means collect a lot of light on a single pixel. If you get into it you can find the electron depth before the pixel is "full" allowing longer exposure to overcome the noise of the CCD. The camera I have is more pizels, but also has two issues; one it is color so the resolution is less, and two the pixel size is 3 micron. The "Full well" on my camera is some 15K electrons at which point that pixel is blown out, on the one you link? 100,000 electrons. Oh, it also cools the sensor to -50C to further reduce noise and make sure that your sensor is at the same temp every evening. The Aluma cameras that the local university use are behind spectroscopy equipment and are mainly used for exoplanet studies. For more realistic users these are the way to go. 46K electron well, full frame compared to a 35mm camera, 5 micron pixels, onboard memory buffer. The problem is that CMOS is tricky and each CMOS chip can come off the wafer a bit different. CMOS is not used so much in research, but with the ASI071 you can take some "amateur" pictures that rival the pros. One example The advantage of CMOS is that the read noise is so low that 5 minute exposures overcomes the chip noise. So take 30-40 five minute exposures in each color wavelength, fire up photoshop and make something pretty.

The way you convince the wife, by the way? The Seattle Astro club has a nice looking dark sky site about 30 minutes from downtown Seattle, next to Snoqualmie Point Park. Not as dark as I would like, but close enough to the city to be something you can attend one of their events. They also do events in the city parks, but as you say the weather in Seattle is... challenging.

This is what the real nerds are using for adaptive optics. The problem with the one you linked is that it only works with their cameras. The university here is running these on every telescope that is doing research. The problem with AO is that you need a 20" class instrument with a very large imaging circle on the back end. "Lucky Imaging" basically what us planetary people use, eliminates the need of AO due to taking thousands of images and throwing out the trash. The deep sky people take 5-7 minute images and then stack just like I do. The only guys I know using this level of AO gear at the people doing photometry on asteroids. A gang of "Amateurs" is doing timing on the near earth stuff and then sending in that data to, I think the Naval Observatory, that then compares all the imagery to get better size and distance data on the near earth stuff.

kleinbl00  ·  54 days ago  ·  link  ·  

Yeah unfortunately the Seattle guys go south an hour of me before they go east an hour from me thereby making it impractical... and their normal viewing conditions are shit. I mean, at least I was hauling my shit out to Gold Bar. Meanwhile, closer at hand...

    Upcoming Star Parties

    Date:

    (weather permitting) Location of Star Party

    tbd - March? Star party at Ron Tam's (when clear weather returns)