Reminder: The bleeding edge JDK builds that are available at builds.shipilev.net, are also available as Docker images: hub.docker.com/r/shipilev/o... -- useful to track down JDK bugs. There are fastdebug builds too.

Some day most telescope manufacturers would realize that the majority of customers use their expensive astrographs with EAF permanently attached, and do the foam cuts in their boxes to accommodate that. That day is unfortunately not today. One can flip and do the ugly cut, though.

Remastered the recent full Moon shots from the best data I had that night: app.astrobin.com/i/xp3dn4

Got my new imaging rig through its first 2 hours of deep-sky work: app.astrobin.com/i/vvcd9r

Full Moon (November 2025) -- first data processed from the stripped down FRA500 setup, which I nominally assembled for deep-sky. But it can be adjusted for non-demanding planetary work too: app.astrobin.com/i/zfk64u

Yay, new imaging rig assembled and tested on terrestrial. Not visible here: f/3.9 reducer which, combined with 90mm aperture, is going to make this uberfast, cutting exposures (smashes calculator) 4x compared to old one. Useful when I have only a few hours a week shooting things.

How dry do you want your astro-camera to be done? -- Yes.

RepairCafe: Saturday, Oct 25, 11:00..15:00 at Potsdam SLB. Come bring your curiosity and your broken devices. We can tinker together, maybe successfully, maybe not, but it should be fun either way. We speak German, English, Russian.

Processed C/2025 A6 (Lemmon) comet result is now here: app.astrobin.com/i/le4ios. Bonus: tail video to show how the tail develops over time: app.astrobin.com/i/34bmp1

High integration time and low light pollution are good, for sure. But you can and should just get out and shoot stuff, because "any data >> perfect data" in this game. These two are 10x60s stacks, with a "slow" f/7 scope + dual narrowband filter, from a very bright city center.

I loved you, Coronado PST. I hated you, Coronado PST. You gave me the best Sun Hα images. You gave me the worst Sun Hα images. Now it is time to fulfill your destiny and become the integral part of much larger imaging train. (Shout out to AOK Swiss for consulting and adapters!)

High-maintenance hobby is: you do not really want to go outside Sunday night and freeze your bottom off, but if you don't, the next chance you will be able to do so is in 1350+ years. (Imaging C/2025 A6 (Lemmon) comet)

(looks at another hair-raising concurrency bug and taps the sign again)

Finally moved my most promising astrophotography results from the last months to AstroBin, enjoy: app.astrobin.com/u/shade

A periodic reminder that you can re-process iconic Hubble images from the publicly available Hubble raw captures using the pretty standard astrophotography tooling. Since all of this is synthetic color, you can choose your own for extra trippy results.

Ever seen a verbose render how a very small GC operation looks like in the context of larger safepoint? Here it is: (I need to blog about things you can see there)

Argh, this hobby is half frustration. The mosaics was miscaptured with clipped edge. Why could not it clip on the DARK edge? Argh. So close to 200 megapixels. Argh.

3x Barlow pushes 80/560 refractor and 2.0μm pixel camera way below the diffraction limit for pixel-perfect resolution. You can still recover some by post-processing tricks. This photo is 9Kx9K, likely very printable! Downsampled 4x here for preview:

If you ever find yourself unsure where you are in relation to the Universe, look up, find Saturn, and check it looks perfectly straight. ᵗʰᵉ ᵒᶠᶠᵉʳ ᶦˢ ᵗᶦᵐᵉ⁻ˡᶦᵐᶦᵗᵉᵈ ⁻⁻ ᶠᵒʳ ᵇᵉˢᵗ ʳᵉˢᵘˡᵗˢ ᵖᵉʳᶠᵒʳᵐ ᵗʰᵉ ᵖᵒˡᵃʳ ᵃˡᶦᵍⁿᵐᵉⁿᵗ ᵒᶠ ʸᵒᵘʳ ʰᵉᵃᵈ

Using narrowband filters (Baader Solar Continuum 7.5nm in this case) does improve Moon contrast quite a bit, even though it pushes the exposure times way up. A doublet with heavy chromatic aberration gets fairly monochromatic light :P [Downsampled 4x here for preview:]

Trials for high resolution full Moon mosaics are in progress. You don't need a cooled camera when it is already cold outside 🥶.

Trying out Baader Solar Continuum 7.5nm filter. Pros: contrast improves quite a bit. Cons: narrowband means longer exposures, with 3x Barlow it goes into 50ms, which turns lucky imaging into REALLY LUCKY imaging. Left: what SDO sees. Right: what my scope sees.

This is happening. I have been using PixInsight for deep-sky and most of the solar/lunar work during the 45-day trial period, and it did not disappoint. Best €350 I spent on astrophotography stuff so far.

Astrophotography things I believed in half a year ago: expensive acquisition hardware. Things I believe in now: expensive post-processing software, plus post-processing skills. Same raw data, drastically different outcomes.

30 minute total exposure of M31 (Andromeda Galaxy) + M110 companion from the bright Potsdam city center.

Me: "Astrophotography in the city sky is so frustrating, so much light pollution". Also me: <deploying the photo rig literally between two streetlights>

I find it amazing that amateur gear can track so well. Doing a single shot with 15 min exposure, through the open window, with 10 °C gradient between room and outside, in strong wind, gives you this! ~1° FOV means the sky moved ~3x the frame width during this exposure. What.

RepairCafe: Saturday, Sep 27, 11:00..15:00 at Potsdam SLB. Come bring your curiosity and your broken devices. We can tinker together, maybe successfully, maybe not, but it should be fun either way. We speak German, English, Russian.

New toy, "residence graphs": tracking the compilation level for top method in the stack. On the left, normal JIT mode: compilers are busy, intp -> T2 -> T3 code is hot; T4 code slowly takes over. On the right, normal AOT+JIT (Leyden) mode: AOT code carries most of it, JIT happens to plug the holes.

"Method Tracing" in async-profiler: github.com/async-profil...

Trying out off-axis guiding instead of guidescope: hitting the focus on both cameras in the same train is such an nuisance, especially with flatteners. But it tracks well once you figure it out. Here, M11 with 64x30s subs, mostly for higher SNR:

The 50x50cm canvas print is here, and it does look pretty nice!

30 minutes light from M16 through SV220 narrowband filter. AM5N is also apparently capable of tracking for 300s exposures without much problem, even with a not well matched guidescope, should be even better when OAG arrives.

Dual narrowband filters for OSC cameras FTW. On the left: ~40 minutes integration with plain UV/IR cut. On the right: ~20 minutes integration with SV220, in much poorer seeing. Fewer stars, better contrast, quite a bit more detail.

Sun Hα, 8x disk + limb mosaic, 6700x6700px (~57cm at 300dpi), remastered from 2 week old capture. This is the best Sun Hα shot I have so far. Feels like squeezing the final performance drops from Coronado PST, which is ostensibly visual only instrument, ha! I mean, Hα!

Sun Hα, full-disk, processing in negative colors. This looks rather nice when printed. (forgot to post it last month)

99% Moon shots from before the Lunar eclipse day.

The government does not want you to know that Blood Moon is actually alive and bleeding through its craters. You can only see it with specialized hardware and a bit of software post-processing. All astrophotographers are on it, and part of the global cabal to k NO WAIT I APOLLOGI

Had 20+ people ask me about stuff in 2 hours. So I decided: if I go back to Potsdam Luisenplatz on Sunday night for lunar eclipse observations, it will be for full visual with binoviewer, matching eyepieces, etc. Weather permitting, it is going to be awesome.

"Gentlemen, you can’t fight in here! This is the Department of War!"

First success at 8x Sun Hα mosaic: 5.7K disk in good detail (downsampled here). Coronado PST is a visual instrument, so brightness is not uniform across the field, which gives lots of trouble with compositing. But it almost works, if you are very patient!

More Eagle Nebula, with a little more exposure from last night.

A day worth of massaging Leyden into training with slower/optimizing compiler and delegate the untrained compilations to faster/not-that-optimizing compiler at runtime. This would be nice to replace all those -XX:TieredStopAtLevel=1 suggestions for much more efficient config.

Welp, TIL that if you crank R-B white balance settings for ZWO camera, it does not only affect the preview, but the freaking *raw capture* would not have anything interesting in green channel at all. GAAAH, WHY, ARGH.

RepairCafe: Saturday, Aug 30, 11:00..13:00 (shorter closing time) at Potsdam SLB. Come bring your curiosity and your broken devices. We can tinker together, maybe successfully, maybe not, but it should be fun either way. We speak German, English, Russian.

Let's go, first ever nebula on this imaging rig. No real set up, 30 minutes integration time through an open window from inside my apartment in Bortle 6 skies.

On this photo: amateur German astrophotographer cannot go into a German restroom without his own German equatorial mount.

First attempt at Sun mosaic in white light: 20x panel mosaic with imperfect stitching gives 8K full Sun disk image. I made a few acquisition mistakes, which means it could be even better! Ohhhh... The compressed / downsampled preview here does not do it justice:

First and not very successful Moon 8x mosaic. Mis-configured the mosaic planner, so incomplete disk was captured. But this theoretically allows 7K pixel wide disks! With more shots and 2x resampling, up to 14K pixels wide? Gotta try it next. Downsampled to 2K here for preview:

Largest capture (8Kx4K frames, 120 GB) with lots of high-quality lucky frames allows for 2x resampling during stacking, taking 100+ cpu-hours. This is the highest resolution full-disk Sun I got in white light so far, measuring 4K pixels in diameter. Down-sampled here for preview: