#soylent | Logs for 2025-08-31
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[04:56:29] <c0lo> TIL https://en.wikipedia.org
[04:56:30] <Clippit> ^ 03Fat tax - Wikipedia
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[08:04:38] <halibut_> The Fat tax article linked to this, which I also found interesting: https://en.wikipedia.org
[08:04:39] <Clippit> ^ 03Pigouvian tax - Wikipedia
[08:05:04] <halibut_> I originally thought the name was more closely related to the fat tax, but it turns out it is based on the name of the person who proposed the general idea.
[08:08:30] <c0lo> halibut++
[08:08:30] <bender> halibut: 23
[08:24:56] <chromas> oleophobia
[08:31:41] <Ingar> that's what she said
[08:34:40] <halibut_> I had just settled down for my ritual nightcap and smoke -- half a glass of brandy and an imported cigar of my most recently favored brand. I sniffed the cigar, drawing it under my nose, savoring the rich tones of the scent. I was just about to light it when she walked in. ``Oleophobia,'' she said, and walked out.
[08:34:49] <halibut_> No, seriously ... that's what she said.
[08:35:11] <halibut_> Not a clue what it meant.
[08:53:52] <Ingar> "Go wash your hair"
[08:55:36] <halibut_> Oh. It makes so much sense now. Thanks.
[08:58:11] <Ingar> Don't mention it :)
[08:58:41] <Ingar> http://ingar.intranifty.net
[08:58:48] <Ingar> for you creatures of the night
[08:59:40] <chromas> noiiice
[08:59:44] <chromas> Ingar++
[08:59:44] <bender> ingar: 18
[09:00:08] <Ingar> chromas: thanks! it actually turned out better than I expected
[09:01:01] <halibut_> Gorgeous.
[09:01:29] <Ingar> still, I should add an extra layer with hydrogen-alpha, add some extra red to the image
[09:02:23] <halibut_> I am always impressed because you can easily find this in a telescope. You think you can make out all of the galaxy, but it is just too faint to see spiral structures by eye ... but then you look at a photograph like this and see that M32 is actually overlapping the outer parts of the galaxy, whereas by eye it is so far away from what you thought was the edge of the galaxy.
[09:03:15] <halibut_> You have an H-alpha filter? Is is a passive filter, or do you have one of those etalons that requires temperature stabilization for a real narrow band?
[09:04:24] <Ingar> halibut_: I have an H-alpha/OIII dual band filter for astrophotography. The H-alpha filters for solar are a LOT narrower (and a lot more expensive)
[09:05:03] <Ingar> e.g. my filter has a bandpass of 3 nanometer
[09:05:26] <Ingar> etalons et all go down to the Angstrom level
[09:09:03] <halibut_> ``Narrow'' means a wide range of things here, I suppose. Still, 3 nm is pretty narrow. That seems to narrow to just be a colored filter. Probably a series of alternating coatings or something.
[09:09:54] <halibut_> Andromeda looks pretty weird in the UV, too. If you had a filter for that (and your imaging device was sensitive enough there), you could make a really weird-looking Halpha + UV image.
[09:13:03] <halibut_> Out of curiosity, why are H-alpha and OIII combined? Is it just that they are different enough colors that you can separate them via other means (like the RGB filters I am guessing are on your camera), so there is no reason not to do both at once?
[09:14:23] <Ingar> halibut_: for color cameras. You get the H-alpha in the R channel and the OIII in the G and B.
[09:15:39] <Ingar> in a mono setup you'd have to do two images with a single-band filter (but your mono camera would be far more sensitive)
[09:15:41] <halibut_> Makes sense. OIII is pretty ionized, so I am guessing that highlights gas and dust near blue stars. Is that correct?
[09:16:35] <halibut_> Are the stars fairly dim in OIII, or do the blue stars show up pretty well?
[09:17:03] <Ingar> halibut_: H-alpha and OIII are very common in emission nebulae
[09:17:38] <Ingar> stars show up pretty well, they're usually far brighter than any nebula emissions
[09:18:07] <halibut_> Even red or yellow stars?
[09:18:55] <halibut_> Hmm ... I guess our sun is hot enough to have pretty strong emission around 500 nm, so I guess that would be enough to show up in an OIII filter.
[09:19:10] <Ingar> halibut_: this is with the dualband filter: http://ingar.intranifty.net no separate stars
[09:19:49] <Ingar> halibut_: I remember something about the Sun and OIII and continuum spectrum, but the details escape me atm
[09:20:07] <halibut_> The stars show up as white, so I guess they show up pretty strongly in the H-alpha, too.
[09:21:19] <Ingar> they emit enough stuff on all frequencies to saturate the sensor's pixels
[09:21:36] <Ingar> althoug they tend to go a bit greenish in dual band images
[09:21:52] <Ingar> I do ofc, mess with the colors in post processing ;)
[09:22:37] <halibut_> The EXIF data for that North America nebula picture (which is also really pretty) says 10h40min. Was that the exposure time? Did you manage to do that all in one night, or was it multiple nights? How many separate exposures did you overlap?
[09:22:50] <halibut_> (Any satellite photobombs that needed to be skipped?)
[09:23:35] <chromas> I knew it! The photos are fake! Stars are fake! The sky is just a reflection of earth in the sky dome
[09:24:13] <Ingar> halibut_: the EXIF comment actually says "80x480s, 10h40min" ;) 80 exposures of 480 seconds each, 10h 40min total
[09:24:54] <Ingar> chromas: actually, the main reason for fake images is because we have to clean out light pollution which is the reflection of the earth in the sky dome
[09:25:08] <halibut_> I should have figured that out.
[09:26:14] <Ingar> halibut_: np ;) I was already surprised you took the time to look at that information :)
[09:28:21] <halibut_> Naturally, Ingar's photos also have the cats removed from them. (Referencing an old Internet joke about space cats photobombing Hubble images and needing to be edited out -- could not find it with a quick search, though.)
[09:28:36] <halibut_> How long does it take to stack 80 images?
[09:29:42] <Ingar> halibut_: a few minutes, but I have a 16-core CPU and 64GiB RAM
[09:29:49] <Ingar> YMMV
[09:30:37] <halibut_> Is that just computation, or does that include the time you spend looking at them and aligning them?
[09:31:21] <Ingar> it takes far more time to prepare the images (remove bad ones, make calibration images, ....) and the post-processing (gimp)
[09:31:49] <Ingar> halibut_: so, just the computation
[09:32:37] <halibut_> I was wondering more about the time you spent on it, not the computer. I figured that was the larger time component.
[09:33:02] <Ingar> at all depends ofc, but "a few hours" is not uncommon
[09:33:51] <Ingar> you want to take your time exploring the image, see what data is in there
[09:34:19] <Ingar> how far you can push it to bring out the faint stuff
[09:34:46] <halibut_> It is pretty neat that you are willing to take the time to do that, and share with us. I appreciate it.
[09:35:19] <Ingar> with pleasure
[09:35:23] <Ingar> space is awesome
[09:35:34] <Ingar> and it is "up there" for everyone
[09:36:15] <halibut_> ... but currently has a very effective ``look but do not touch'' policy.
[09:37:10] <halibut_> Even without the difficulty of crawling in and out of gravity wells, the distances to even the ``nearby'' destinations is mind boggling.
[09:37:11] <Ingar> but we can peek without shame or reprecussions
[09:38:16] <Ingar> in the meanwhile, the cat has been attention-whoring me all morning
[09:38:56] <halibut_> Time for me to be AFK. Thanks again for sharing. (.. also, train the cat to stack images)
[09:39:44] <Ingar> halibut_: cu later!
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[14:36:16] <fab23> =submit https://hacks.mozilla.org
[14:36:17] <Clippit> ✓ Sub-ccess! "03Just a Moment..." (1p) -> https://soylentnews.org
[17:46:55] <janrinok> =submit from jan https://www.techspot.com
[17:46:56] <Clippit> ✓ Sub-ccess! "03Just a Moment..." (2p) -> https://soylentnews.org
[17:53:15] <janrinok> =submit from jan https://go.theregister.com
[17:53:17] <Clippit> ✓ Sub-ccess! "03China Turns on Giant Neutrino Detector" (11p) -> https://soylentnews.org
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