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Hasselblad posted:Satellites do not change course several times over the span of a couple minutes (at least not enough to be noticeable to the naked eye) I wasn’t talking about your spooky x-files stuff.
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Jul 29, 2019 05:04
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Near the horizon you get all sorts of atmospheric effects which can play all sorts of fun with visible sightings. The closer to the horizon, the worse it gets. Those are typical satellite sightings. Not even necessarily iridium flares.
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Jul 29, 2019 05:15
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Platystemon posted:Your description sounds like an Iridium flare. Thanks, this certainly fits. Amazing how bright they can get.
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Jul 29, 2019 11:52
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what you saw was the light from venus reflected off swamp gas
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Jul 29, 2019 13:43
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OMGVBFLOL posted:what you saw was the light from venus reflected off swamp gas No other object has been misidentified as a flying saucer more often than the planet Venus.
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Jul 29, 2019 14:20
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AFewBricksShy posted:No other object has been misidentified as a flying saucer more often than the planet Venus. I've had people think Venus was a UFO in my presence and didn't believe me even when I offered to haul out my telescope to show them.
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Jul 30, 2019 03:25
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Hell, I've looked up and thought Venus was an airplane before.
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Jul 30, 2019 06:04
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Alright, I think I'm going to go a bit over budget, which is completely fine, and get a Explore Scientific Carbon Fiber ED102 f/7 APO Triplet and a Celestron Advanced VX. The Asteotech stuff looks really great, and ideally I'd buy something of theirs, but the good stuff is out of stock and I'm in a bit of a time crunch. I can afford the extra spend, and the carbon fiber thingy is on sale for $300 off so it doesn't seem as stupid of a purchase.
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Jul 30, 2019 06:17
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Sometimes I entertain the idea of doing astrophotography. What usually calls to me is an imagining newt, but I know what the practical option is to start with a small refractor like the ST80 that I already own.
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Jul 30, 2019 06:57
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AFewBricksShy posted:No other object has been misidentified as a flying saucer more often than the planet Venus. why, even the former leader of our united states of america, james earl carter jr, thought he saw a UFO once
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Jul 30, 2019 07:10
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OMGVBFLOL posted:why, even the former leader of our united states of america, james earl carter jr, thought he saw a UFO once Your scientists have yet to discover how neural networks create self-consciousness, let alone how the human brain processes two-dimensional retinal images into the three-dimensional phenomenon known as perception. Yet you somehow brazenly declare seeing is believing? Mister OMGVBFLOL, your scientific illiteracy makes me shudder, and I wouldn't flaunt your ignorance by telling anyone that you saw anything last night other than the planet Venus, because if you do, you're a dead man.
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Jul 30, 2019 11:54
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Internet Explorer posted:Alright, I think I'm going to go a bit over budget, which is completely fine, and get a Explore Scientific Carbon Fiber ED102 f/7 APO Triplet and a Celestron Advanced VX. The Asteotech stuff looks really great, and ideally I'd buy something of theirs, but the good stuff is out of stock and I'm in a bit of a time crunch. I can afford the extra spend, and the carbon fiber thingy is on sale for $300 off so it doesn't seem as stupid of a purchase. Are you talking about this one? https://explorescientificusa.com/collections/telescopes/products/ed102-fcd100-air-spaced-triplet-telescope-carbon-fiber That is some serious business!
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Jul 30, 2019 13:50
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Seriously, that setup sounds awesome. A refractor at F/7? Hell yes. And the AVX should be great to get started with that scope.
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Jul 30, 2019 14:01
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Thanks for the feedback on PEC/PPEC on the previous page, I'm just trying to understand the limitations of it. I have caught myself making small adjustments with the clutches engaged prior to polar alignment and, while I'm going to try to stop doing that, was curious if it would mean I'd need to record an entirely new PEC curve if I screwed up again in the future. I did get out on Friday with my new tracking scope and camera, a ZWO ASI120MM-mini on a Astromania 50mm guide scope. Things seemed to work fine, the ASI120MM-mini is unsurprisingly a low-res camera but even in the city light pollution, I had no issues finding a star that was the right size to track with near my target. It seems like a really nice guiding solution for use with PHD2 on a budget.
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Jul 30, 2019 14:08
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Rolabi Wizenard posted:Are you talking about this one? Golden-i posted:Seriously, that setup sounds awesome. A refractor at F/7? Hell yes. And the AVX should be great to get started with that scope. Sweet! Glad it looks like a good choice. I went back and forth in a bunch of different options and I just couldn't find something I was happy buying for ~2k. I really wanted something portable and all the comments I've seen about the AVX not being able to carry much weight kind of sealed the deal for me. I don't want to get a much bigger mount and I'm going to have to move and store this stuff, so smaller and lighter is better. Didn't want to do 80mm because I think it will be more limiting, but I don't want to do something too large due to the added bulk and difficulty in use.
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Jul 30, 2019 19:43
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Platystemon posted:Sometimes I entertain the idea of doing astrophotography. One of us! One of us! Golden-i posted:Thanks for the feedback on PEC/PPEC on the previous page, I'm just trying to understand the limitations of it. I have caught myself making small adjustments with the clutches engaged prior to polar alignment and, while I'm going to try to stop doing that, was curious if it would mean I'd need to record an entirely new PEC curve if I screwed up again in the future. I finally got my OAG working. Getting the thing parfocal sucks. I have a QHY5L-II and an ASI120MM (both mono astro cams, but I think the QHY is more sensitive) and was trying to use the ASI120MM but the sensor needed to be further down inside the OAG to reach focus so I switched to the QHY. (I'll use the ASI120MM on my other refractor as I can use it on a normal guidescope) Got it working finally and did some measuring of my EQ6-R's guiding performance. I've been getting orthogonality errors (>20 deg offset) and pretty bad backlash on dec. I'm going to try and tune it (found instructions online) and see if I can fix that. Even with all that, I can get ~1" guiding, which I find acceptable for the skies here. I don't need super-long subs where I am anyway - between the light pollution, and the ASI1600MM's sensitivity, I'm reaching ideal subs between 10-30s depending on filter.
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Jul 31, 2019 00:55
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AFewBricksShy posted:Your scientists have yet to discover how neural networks create self-consciousness, let alone how the human brain processes two-dimensional retinal images into the three-dimensional phenomenon known as perception. Yet you somehow brazenly declare seeing is believing? Mister OMGVBFLOL, your scientific illiteracy makes me shudder, and I wouldn't flaunt your ignorance by telling anyone that you saw anything last night other than the planet Venus, because if you do, you're a dead man. this definitely rates about a 9.0 on my weird-poo poo-o-meter
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Jul 31, 2019 06:12
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OMGVBFLOL posted:this definitely rates about a 9.0 on my weird-poo poo-o-meter https://www.youtube.com/watch?v=OYYyUFb2wCQ
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Jul 31, 2019 12:36
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Sorry for spamming the thread with my stupid newbie poo poo, but possibly the last update for a bit. Long story short, I didn't end up with the gear I wanted (Celestron AVX, ES ED102 cf) and I while it's the safer choice, I think diving into the deep end would have worked well for me. I went to my local astro store to pick up the gear I was talking about earlier and the guy there was super helpful. He was pretty adament that I not buy that much equipment being new to the hobby, which I completely understand and appreciate. I expected that to happen and any same person would say the same thing. Signs of a good shop, definitely. The more we talked the more I figured I'd give the safe route a shot. Kinda disappointed, but oh well. Instead I got a really basic 102mm scope that came with a mount and a carrying bag, and a Star Adventurer Pro. The scope is a Meade Infinity 102mm Altazimuth Refractor. The line of thinking was to have a basic scope to look through and get used to things, something easy to carry and store. Then use the Star Adventurer Pro with my photography tripod and mirrorless + decent astro lenses I already have, using that as a way to get better at things like alignment and tracking. I'll probably give the scope to some nieces and nephews in the next year or so when I upgrade. It was only $250 and would make a decent hand me down gift for the little ones. So now my approach is going to be to basically build up what will eventually be an ancillary setup to something more serious down the road. The tripod, star tracker, and camera will always be useful for nifty pictures of the Milky Way. My next thing might be to pick up one of the AstroTech 80mm scopes that are small enough to use with the star tracker. Then after a bit, waiting patiently for a great deal, pick up a bigger scope and a proper mount. I dunno. Maybe my newbie ramblings will be helpful to someone also considering getting into the hobby.
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Jul 31, 2019 15:16
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Internet Explorer posted:Sorry for spamming the thread with my stupid newbie poo poo, but possibly the last update for a bit. Long story short, I didn't end up with the gear I wanted (Celestron AVX, ES ED102 cf) and I while it's the safer choice, I think diving into the deep end would have worked well for me. That all sounds very sensible, and excellent service from the guy in the shop. Have fun with your new scope! You can do a lot with a 102mm refractor.
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Jul 31, 2019 15:41
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pointsofdata posted:That all sounds very sensible, and excellent service from the guy in the shop. Have fun with your new scope! You can do a lot with a 102mm refractor. I agree. The service was excellent and was giving good advice. Seems like a great shop.
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Jul 31, 2019 17:32
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hannibal posted:One of us! One of us! My goal is to get up to 5 min exposures to improve my S:N ration when I shoot at home, where the light pollution is nastier. Maybe 4 min, depending on how bad it is, but I have to run the camera at a very high gain to get my histogram anywhere near where I want it in a ~1min exposure and I feel like I'm losing a lot of detail to the noise reductions required in post-processing. I'm going to see how things go this weekend at the cabin, try recording and applying PPEC to see if that helps with guiding at all. Should be a fun time.
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Jul 31, 2019 21:51
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pointsofdata posted:That all sounds very sensible, and excellent service from the guy in the shop. Have fun with your new scope! You can do a lot with a 102mm refractor. I agree. This hobby has a steep learning curve, best to start towards the low part of it. Golden-i posted:My goal is to get up to 5 min exposures to improve my S:N ration when I shoot at home, where the light pollution is nastier. Maybe 4 min, depending on how bad it is, but I have to run the camera at a very high gain to get my histogram anywhere near where I want it in a ~1min exposure and I feel like I'm losing a lot of detail to the noise reductions required in post-processing. I'm going to see how things go this weekend at the cabin, try recording and applying PPEC to see if that helps with guiding at all. Should be a fun time. What's your camera, again? It's worth learning a bit about how the sensor works in terms of read noise, etc as it's a more rigorous way of figuring out ideal exposure times. I feel like I recently graduated from 'hmm that histogram looks ok' to looking up ADU exposure charts for sensors and figuring out things from there. Jon Rista on CL has a basic rule that I think is good, using 20x read noise as a starting point for proper S/N ratio.
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Jul 31, 2019 23:56
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There was a transit of the ISS across the Sun visible from my location today. I was able to record it, full details here: https://www.instagram.com/p/B0sMnqWF-qy/ First one of these I've been able to catch, which was pretty neat. Now to wait for a lunar transit... (you can find out if the ISS is going to transit the Sun or the Moon at http://transit-finder.com)
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Aug 3, 2019 07:13
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hannibal posted:There was a transit of the ISS across the Sun visible from my location today. I was able to record it, full details here: https://www.instagram.com/p/B0sMnqWF-qy/ Awesome stuff, nice job!
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Aug 3, 2019 16:32
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hannibal posted:What's your camera, again? It's worth learning a bit about how the sensor works in terms of read noise, etc as it's a more rigorous way of figuring out ideal exposure times. I feel like I recently graduated from 'hmm that histogram looks ok' to looking up ADU exposure charts for sensors and figuring out things from there. Jon Rista on CL has a basic rule that I think is good, using 20x read noise as a starting point for proper S/N ratio. I've got the ASI294MC-Pro, and I've also been reading up on the ADU charts and stuff, mostly trying to figure out exactly how this stuff works. I tell you, though, this is confusing, so it'll be an ongoing effort. I did get out last night and tried out the new guiding camera/scope with PHD2. It works like a charm! I got 3-minute exposures with very little drift, and definitely could have done more but it was a little cloudy and I didn't want to risk losing too much of my exposure time to cloudy frames. I went for the East Veil Nebula, mostly because seeing conditions were poo poo due to the humidity and it was almost straight overhead when I was shooting, and I wanted something with some detail to really test out the guiding camera's accuracy. The East Veil Nebula  30x180sec frames, 5 dark, 10 flat Celestron 8" Reflector @ ~1000mm F/5 ZWO ASI294MC-Pro camera (captures), ZWO ASI120MM-Mini camera (guiding) SkyWatcher EQ6-R mount EQMod, Sharpcap for captures/plate solve, Stellarium for tracking, PHD2 for guiding Processed in PixInsight To be honest, this target is way, waaaay to big for this telescope to shoot, of course... I could only fit this arm into the frame. I don't have a coma corrector so you can see the edges and corners streaking outwards, but I was really happy with the detail I could get. I'll definitely be shooting this again when I have refractor or something else with a shorter focal length, but I'm really happy with how it turned out.
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Aug 4, 2019 17:17
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hannibal posted:There was a transit of the ISS across the Sun visible from my location today. I was able to record it, full details here: https://www.instagram.com/p/B0sMnqWF-qy/ Woah, this is so freaking cool! I've always wanted to try and catch a lunar transit, but never had the luck. Nice!
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Aug 4, 2019 17:36
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Yeah, it took me a while to figure things out too. I'll try to explain, and take all this with a grain of salt as I'm still figuring things out myself. In terms of measurement, you're looking for an ideal ADU value to expose for. This is the equivalent of eyeballing the histogram, but is a more precise and rigorous way of determining exposure based on the sensor's characteristics. That way we avoid the subjective arguments over 1/2 histogram vs 2/3 histogram, etc. Some terminology: ADU = analog-to-digital unit, a representation of the minimum sampling possible by the camera's analog-to-digital converter, ADC. Camera ADCs are measured in how many bits they represent in their values: 8, 10, 12, 16 are popular. DN = Digital Number, a more generic representation of the same idea and you'll see these used interchangably sometimes. Usually ADU is used when you're talking specifically about a sensor's characteristics, and DN is a broader term meaning discrete steps of pixel measurement. We need to determine the sensor's characteristics, which are usually stated in electrons, and convert that to ADUs. Similarly, the camera's gain is measured in electrons/ADU. (basically, how many electrons does it take to move the needle to the next ADU? Since they're the minimum step size) Note that this is not the large number normally presented by the software. You'll also see mention of "unity gain" which is 1e/ADU. For the ASI294 this is at gain setting 120. (I read elsewhere that ZWO's gain numbers are tenths of a decibel above minimum gain, so that would be 12db gain, which is a more signal-processing-y way to look at it) The main factor in exposing is swamping read noise with signal. Read noise is a catchall term for any noise generated by the electronics themselves in the act of reading the sensor, not related to actual signal - stuff like reading the elements of the CCD, random thermal noise (not hot pixels), etc. Thus it sets a absolute minimum floor below which you'll never see anything. (You handle other noise sources with calibration - bias, darks, flats) There are multiple loose rules out there for how much signal is needed to swamp read noise. Jon Rista on CL used to advocate 20x RN but now proposes 10xRN^2 after some refinement and discussions with others. We'll go with that. Some people have gotten really specific and built models to provide proper values here, as read noise changes with gain and there are other factors like amp glow that can factor in at longer exposure times. But this is a good rule of thumb for now. We also need to factor in the sensor's bias (aka offset), which is simply a minimum value we add to the ADUs coming off the sensor that establish the 'floor' of the sensor's readout. (in photographic terms, the black value) Going with the above RN swamping, we can use this formula for doing the conversion into ADUs, incorporating offset and gain: MinDN16 = (((ReadNoise^2 * swamp) / gain) + bias) * (2^16/2^Bits) where: ReadNoise = read noise in electrons swamp = swamping factor: how much signal to use to swamp out the read noise gain = gain of the camera, in e/ADU (for unity gain, this would be 1) bias = the bias offset in ADUs used by the camera bits = bits of precision in the ADC - 8, 10, 12, 14, 16 Your camera's manual has more specific information on gain and read noise (since it varies). As mentioned, unity gain is setting 120 (1 e/ADU), and apparently that camera has some special mode past that where it further reduces read noise. But going with 120 for now and apparently a fixed offset of 30 (from what I can tell online), you'd have: Read noise = 2 (at unity gain according to their chart) Swamp = 10 (per recommendations) Gain = 1 (unity gain) BiasOffset = 30 Bits = 14 MinDN16 = (((2^2 * 10) / 1) + 30) * 2^16/2^14 = 280 ADU So 280 is the absolute minimum you need to capture signal, using this rule (in 16-bit). That's important because, any exposure over this amount isn't adding much to your SNR, so isn't really doing you any good, for that purpose. There may be other reasons why you want longer subs though, it's not a bad thing. So, we haven't talked about the sky yet. How do you use this in practice? Basically you take a sub, measure the background, look at the median ADU, and get it at or above that minimum ADU. You can do this in Pixinsight, or with SGP, and I'm sure with other software as well. That is where it truly becomes the equivalent of eyeballing the histogram. When I did this with my ASI1600 I was kind of blown away at how the histograms would look - mostly just a peak at the left side and nothing like the 1/3 histograms I was using before. (you can read all about the ASI1600's exposures here) You can of course go with higher median background ADU values (thus, more histogram) and expose longer. The main danger there is clipping the bright cores of stars. (You can see this in SGP if you mouse over a star and the value is at 65535, aka the max value you can represent with 16 bits of precision)
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Aug 4, 2019 20:01
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drat, that's extremely helpful. Thanks! the terminology was really hanging me up, I think, so having it spelled out is very useful.
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Aug 4, 2019 21:15
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Golden-i posted:The East Veil Nebula Thats beautiful. Is that from a dark site and/or did you use any LP filters? Great info. Thanks for the great effortpost. Sometimes I see vanguard posters on forums there and there who disagree with conventional wisdom and say that the low noise and sensitivity of recent modern CMOS cameras changes the exposure conventional wisdom coming from the older corners of the internet. Sensors like Golden's ASI294MC are capable of a lot of dynamic range without long exposure times. I don't usually get too deep into it, as my interest is more in visual for solar system objects and live viewing via live stacking for DSOs, not optimizing for super sexy real astrophotography. Robin (SharpCap guy) does into a lot of details about sky brightness, noise, exposure length and such here, it's a great few posts that goes along with hannibal's post.
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Aug 4, 2019 23:09
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Rolabi Wizenard posted:Thats beautiful. Is that from a dark site and/or did you use any LP filters? It's from my bortle-2-ish site, but I did use a LP filter because, of course, there's a god drat streetlight about 100 feet from the only place I can see polaris AND enough of the sky to take exposures... there's a ton of tree cover so my options up there are limited without trespassing. Thankfully, it's an old incandescent-style light, so my LP filter does a great job of blocking it out. It's on private property and we pay for it, so I'm going to call the electric company about getting a switch installed so I can turn the thing off when I'm shooting.
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Aug 4, 2019 23:40
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Rolabi Wizenard posted:Thats beautiful. Is that from a dark site and/or did you use any LP filters? Thanks, it was helpful for me to write it all out for once, because I had to consult some references to make sure I was getting things right. (Including a few books I have, so not just internet forums posters with no sources) My interests lay less in pretty photography and tweaking things in PixInsight (although I still like doing it) but more and more in photometry and related applications (like exoplanet detection) which is where all this stuff about sensors and signal processing actually gets important. Thus why I have been learning the stuff. I slso went to a really informative workshop at NEAIC year before last on sensors and photon transfer analysis where I learned a ton of the stuff about noise sources. I have to say, when I first read that thread about the ASI1600's exposure times, I checked the math like 10 times because of how short the exposures were compared to what I was doing before for 1/3 histograms on DSLRs. SGP shows ADU values in 16-bit always, so I was making sure I was converting correctly from 12-bit and wondering if that was the source of the problem or if I was doing something wrong in SGP - because when I used those ADU values the histogram was really just a spike near the left side and I thought surely that wasn't enough exposure. For my skies here near DC I was ending up with ~10s exposures with the L filter and 30ish for RGB filters, compared to several minutes at least for DSLRs in the past. The nice thing there is that stability is way easier with shorter exposures. I admit I haven't done much DSO photography recently, so I should probably do some and test all that out. But this is what the 'pros' are doing with these sensitive cameras, so I feel like it's gonna be ok. That post by the Sharpcap guy is pretty good, I'll definitely have to pick it over.
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Aug 6, 2019 02:44
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hannibal inspired me so I put my tattered, old, but still awesome Orion 80ED on my old-rear end Nexstar GT, and set it outside with a Baader film filter over the top and pointed it at the Sun. I got it to focus with an ASI224MC with a couple of extension tubes, but the Houston sun was murdering me and my poor MBP so I fled into the glorious AC. Still, I was ready for what would have been a good ISS transit of the sun. But, god drat Houston, the clouds rolled in and I couldn't get it. Being outside in the day time is over rated.
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Aug 6, 2019 03:03
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Same, but also at night time. I've had to buy some insane repellent to fight off the north Minnesota mosquitoes, and even while wearing a hoodie and jeans in the 80F temps and sweating my rear end off, they'll still bite me through my jeans. Bastards. I'm going to pick up a coma corrector for my scope (this one) to help correct the vingetting and streaking that I see, and an EQDIR cable so I won't need the handset on my mount anymore, and hopefully I'll be back out in a few weeks. Maybe the mosquitoes won't be as bad then...
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Aug 6, 2019 15:57
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Rolabi Wizenard posted:hannibal inspired me so I put my tattered, old, but still awesome Orion 80ED on my old-rear end Nexstar GT, and set it outside with a Baader film filter over the top and pointed it at the Sun. I got it to focus with an ASI224MC with a couple of extension tubes, but the Houston sun was murdering me and my poor MBP so I fled into the glorious AC. Still, I was ready for what would have been a good ISS transit of the sun. But, god drat Houston, the clouds rolled in and I couldn't get it. Yeah, I was boiling when I shot that transit the other day. Going to try for another one in a couple of weeks, and just learned there's a Mercury transit in November... Golden-i posted:Same, but also at night time. I've had to buy some insane repellent to fight off the north Minnesota mosquitoes, and even while wearing a hoodie and jeans in the 80F temps and sweating my rear end off, they'll still bite me through my jeans. Bastards. 
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Aug 7, 2019 03:59
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Can we get a mod to just rename the thread to this? Because, gently caress
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Aug 7, 2019 04:05
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Though the coma corrector seems like the best choice at the moment, it's cheaper than a new scope that won't have these issues and I'm still not sure what I want in my next scope.
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Aug 7, 2019 04:09
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Golden-i posted:Though the coma corrector seems like the best choice at the moment, it's cheaper than a new scope that won't have these issues and I'm still not sure what I want in my next scope. I remember finding a review at one point comparing different coma correctors, and the conclusion somewhat surprisingly was that the cheap GSO one worked better than the Baader for half the price. Myself, I designed my own coma corrector based on a random forum post using a program that only works in French (thanks Google Translate!) out of $20 lenses, but haven't gotten it and the telescope quite collimated right yet. 
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Aug 7, 2019 04:34
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Tyrgle posted:I remember finding a review at one point comparing different coma correctors, and the conclusion somewhat surprisingly was that the cheap GSO one worked better than the Baader for half the price. Well, poo poo, I can read french so that might be nice if it could save me the money! Can you point me in a direction on that?
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Aug 7, 2019 04:39
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Golden-i posted:Well, poo poo, I can read french so that might be nice if it could save me the money! Can you point me in a direction on that? Heres a good chat on spacing for the GSO coma corrector, if you decide to go that way. https://www.cloudynights.com/topic/462985-setting-up-the-gso-coma-corrector/
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Aug 8, 2019 03:20
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