Recent content by collinsmark

The Jellyfish Nebula (a.k.a. IC 443, Sh 2-248) scooped up from my back patio, Feb. - Mar. 2025. The nebula is a supernova remnant found in the constellation Gemini. It lies about 5000 light-years away, almost in the very opposite direction of our galaxy's center. To me it looks more like a...

Great composition in those shots! :smile:

... Final post of sister's and brother-in-law's visit, here in San Diego. We spent one day heading down to North Park (a neighborhood in San Diego). North Park is known for its artists community (and some might argue "hipsters" too). It has roughly a dozen art galleries (give or take). Not...

... More from my sister's and brother-in-law's visit, here in San Diego. We dedicated much of one day to visit San Diego's Maritime Museum. While all three of us sail at least occasionally, my brother-in-law sails more than I do (by "sail" I mean wind-powered sailboats). So we were all pretty...

... Continued from previous post. 'Still at La Jolla Cove for these pics. Figure 1. "Untitled." I like this shot; I think there's something there. I just don't like the SUV hogging up the space. I almost didn't post it, and had planned to come back to this location in hopes that the SUV...

My sister and brother-in-law came to visit me for a few days in San Diego last week. Good times were had by all. It was also an excuse for me to get off the davenport and get the rangefinder camera out of the house. We started off heading to La Jolla Cove. Figure 1. "Scuba divers and...

For me it's pretty invaluable. There's a lot of "bang for the buck," once the initial setup/workflow is debugged and figured out. Again, flats aren't just about correcting for vignetting. It's the best way of virtually eliminating dust motes from your data (when possible; where dust motes are...

By an uncanny coincidence, Cuiv, the Lazy Geek released a video a few hours ago introducing calibration frame process flow. And he brings up a good point that might explain (possibly, maybe) what may have been the culprit with @Andy Resnick's flat frame trouble. (See around 26:30 in the video.)

1) Yes, this is true. Any blemishes on the lens/optics must be consistent between lights and flats. That's one reason why I take flats fairly frequently (about 1 set of flats for each deep sky target, and if I revisit a target after a significant amount of time has passed, that's a whole new...

Here's an image I captured last Tuesday night [Edit: actually, Monday night/Tuesday morning], a little less than a week before opposition. Rhea, one of Saturn's moons, can be seen on the left. Saturn's north is "up" in the image. If the rings' shadow and inner rings look a little blue to...

Have you tried flat frame calibration? I'm a stickler for flats. Every deep sky image I've ever posted here I've processed with flat frame calibration as part of the process (planetary doesn't count; I don't do flats for planetary). I take new flats for every new target for each filter I use...

Here's a related video by Matt Parker's Stand-up Maths. (Most people on PF are familiar with Matt Parker from his semi-comedic, math videos [he's also been on Numberphile several times]). This video is about pain scales, but it features the "bullet ant."

Yep, fitting algorithms can sometimes push precision limits. But beware of overfitting. Not only does overfitting waste computational resources, it can lead to erroneous conclusions -- and as possibly applied here: suboptimal control systems.

(Source: https://explosm.net/comics/how-pretty#comic)