Green Baron

Aehm .... no technology we can imagine could make an image of an exoplanet. Even an interferometer the size of earths orbit would not be large enough for an earth size planet at the next star system, not speaking of farther planets. Prove me wrong 'cause i daresay by several magnitudes :-). Also the contrast between a rocky planet and its sun at let's say 10 parsec is far beyond what imaging can do (edit: these days). What probably can be "seen" at that distance is a solar system, infrared from gas giants, we could determine more details about what is known as the "habitable zone"(tm). Which is in the range of a few (like 1-3) AE at 10 pc. That sort of things. JWST is part of a number of new generation telescopes. I am looking forward to what these instruments can deliver as well, though exoplanets are just a small part in the story. Yeah, @Streetwind, planet 9 ! I almost forgot about it ...

I can't give you all the backgrounds but here a few rules of thumb i met: The angular resolution is first and foremost simply a function of main mirror/lens diameter. Rule of thumb after Rayleigh for the minimum distance to resolve two different diffraction discs of stars is a["] = 13,8 / Diameter[cm]. A 115mm telescope has ~1.2", JWST's main mirror has a theoretical 0.02" if my calculator is right, so other elements in the JWST construction must limit the resolution. For photography the pixel size of the camera must correspond with the optics and here comes the focal length into play. a["] = (Pixel Size/Focal Length) * 206.265. An amateur must buy what is offered, so this is the second limiting factor. They should be just small enough to meet the optics resolution but as big as possible to collect as much light as possible. Atmospheric disturbances limit the resolution even more because they cause the diffraction discs to literally jump around. 3rd rule of thumb is that the atmosphere limits seeing conditions to 1" to 3". That's why 120mm is just the perfect amateur telescope diameter if the equipment is adjusted correctly

You sadly are in good company. Light "pollution", besides atmospheric things, is among the biggest problems for all things astro from earth. I lived in the crowded Stuttgart area for many years, from out of the cities only the brightest stars were visible. Out in the fields anything below ~30 degrees above the horizon disappeared in a constant orange glow of dust and artificial lights. Also you couldn't do a many long term exposures without a trail of lights from airplanes. This place here is protected from overflights by night and in theory unnecessary lights are forbidden. In theory ... I have realized that over the last five years the number of satellites has increased. I have a lot of trails on the first long term exposures in the first 1-2 hours after sunset and before sunrise (see below :-)). I gave it another try yesterday before sunrise despite of a high veil of clouds. I've hit the distance corrector-camera better than in the first try in November (am still a little too short as can be seen in the corners). The spikes and blurriness all over the photo are from the high clouds. M45, 9*8min, only L-filter, darks and bias.

That may well be. And the cmos chips have more problems with noise than ccds. A single 8min shot, cooling inactive, with the ccd cam shows far less noise than a 1 min shot with the dslr.

I did a direct comparison a little more than a year ago, when i startet with astrophotography. I recall the data but don't have the pictures any more. I tried with a starfield around Andromeda, good old Nikon D700, 800iso, 200mm Telelens, f/2.8, 2min and 4min exposures on a tracking mount. It was a warm night (maybe 22°C). I used DSS for stacking. Without dark frames single shots were just noisy :-/. From 10 stacked exposures on things got better, but there was still visible noise. With 20 exposures the noise did not disturb me any more in a wide field photo. But i understand that for deep sky objects, where any post correction of noise destroys parts of the nebulosities, this is not recommended. On the other hand 10 exposures with the subtraction of 10 dark frames and 10 bias frames really where an eye opener, i could hardly see any noise any more. I only shirk sitting double time on the hill, so I then decided to give myself the allowance to acquire a cooled ccd-cam. And then the weather decided to show me what "natural advantage" means ... that was 8 weeks ago. And now the moon is shining so bright you can read a book outside ...

Maybe i misunderstood ops question "do stars have L1 and L2 points" for "do stars in orbit around the galaxy have Trojans". Sure, binary star-systems could theoretically have all sorts of L-points, depending on mass and distance and Trojans might be possible in the corresponding L4 or L5. I doubt anyone can give us a serious estimate on the probability of such a configuration. I shortly read a paper about possible Trojans in a system with a gas giant and a sun. The gas giant transits the sun and there was a very weak periodic signal in front of and behind it, that could probably/maybe/nobody knows/let us speculate be interpreted as Trojans. Achilles in outer space :-) If you search "extrasolar trojans" you get a stack of noise and maybe a few serious articles. I recommend not to use google but one of the many alternative search engines (i use duckduckgo but there are others, independent ones). These signals, measurement and interpretation, is at the limit or slightly beyond what the current generation of instruments can do. A new generation is under construction and i am sure that 10 years from now we'll have many more "insights" :-) gb

Lagrange points are not a thing of a single body, they result from the mutual cancellation of the effects of gravity and orbit forces (centripetal/-fugal) of two bodies, where one of them orbits the other. Both masses can be assumed to be concentrated at a single point. That is approximately the case with a sun/a planet or a (dwarf) planet/a moon. The resulting langrange points of such systems are a place that over time attracts small bodies/satellites or provide a place for keeping artificial satellites at low manoeuver cost. The galaxy where the sun is part of is not a single mass concentrated at the center. There are other forces of gravity all around where one would expect a Lagrange point. Also Lagrange "points" are no points but more or less stretched volumes of space with a peak where things must be balanced or valleys where things drop and stay. Edit: not sure about the latter and no time to look it up ... So, the answer is, nope, no Lagrange points in the system Galaxy-Sun. Editedit: i did look it up, L4 and L5 are stable, that is why these points attract Trojans. L1, L2 and L3 are labile, they do not attract Trojans.

Don't summon them, or they show up :-) Sorry, drifting off topic.

Ah, this explains why (and that is in any movie sword fight one of my pet peeves) they always beat on each others blades like crazy, until after minutes of choreography one of them more or less accidentally dies. Some swords (like that of Aragorn) are so ridiculously long you'd be dead (3 times) before it is out of the scabbard. Btw., the guard or crossbar or what you want to call it has, besides guarding the fingers (rather sacrifice a finger than a head :-)), other purposes. It is part of a lot of techniques in medieval long sword fencing, defensive and offensive, when fencing get's so close that it comes to wrestling. I once saw a scull with a hole in the maxilla that exactly fit to a hilt bar of a corresponding long sword.

Looks good. Concerning Spacechem, i once got stuck as well and gave up. Shame on me. Looks like Factorio is playable without a steam account, i'll give it a try :-)

A quick search revealed for example this and this as introduction, this describes it quite good i think. I want that Takahashi refractor in the last link. Edit: Here are the equations, beware of coordinate systems. You'd probably have to rearrange them because you come from the other side, you have positions from observations. How about using a ready made software for that ? Data to play with seems to be available as well: http://ssd-api.jpl.nasa.gov/ Maybe that helps.

*sniff* 'abby dew yeea. *blow nose* :-)

Hi @ProtoJeb21, first the vignetting, that's the dark edges. Source is either the scope's objective/mirror that has an image field that is too small for the size of your cameras chip (or the chip is too large :-)) or something in between (focuser, corrector, filter element, ...) is narrowing the way. If you can live with it i suggest you do it for now. Later on with more proficiency, as @YNM says, flatfield frames and the corresponding dark frames could partly help. Though the vignetting is probably too strong to be corrected. I kindly ask to search the web for the meaning and sense of darkframes in general, some theory cannot harm :-) This leads us to why astronomic cameras are cooled. This is, in fact, not only to reduce noise, but mainly for reproducibility. And why we always use raw files from the camera, never any jpegs or tiffs it might produce. Switch off any automatism of your camera, use manual mode and raw files. Flat fields are made on site, with the fully assembled and adjusted equipment, the scope covered with a grey blanket or, better a flat field foil in a rigid frame. Flat fields, as the name says, are representative for varying illumination that originates from the setup or maybe nearby external light sources. Like vignetting, reflections in the tube or focuser, dust on filter surfaces, ... Exposure time, camera iso setting and chip temperature don't matter but must be all the same, it should be long enough to get an evenly exposed picture without any saturated or grossly underexposed pixels. The corresponding dark frames must, like any dark frame, be made with the same exposure time, iso setting and chip temp. as the flat field frames it belongs to ! You can take the camera off the scope and cover it with the lid, but do not warm it. As to the number of flat field and dark flat field frames: like with everything many are better are better than few, for practical reasons let's say 16 each are sufficient. Btw., only few people do flat field frames. The equipment these days is of good enough quality so that the sources of uneven illumination can be eliminated before they arise. And it's a lot of hassle, more than keeping stuff clean and connecting everything safely and securely. That's why i suggested to skip it. The next is the noise, and there something can be done and must be done because that will reappear with every night shift. Copying a file is not involved anywhere, except for backups later :-) Make your light frames with the setup (i assume a dslr and a tracking mount), a certain iso setting, exposure time and eventually aperture if using a camera lens. Do not switch ! At least 10 should be ok, more are better. Use a timer if your dslr doesn't allow exposures times longer than 30 seconds, like mine. If you don't have a tracking mount then experiment with exposure time, but if you use a telelens you'll have prolonged stars after seconds. Then (or in between, if you dare to touch without moving anything), make your light dark frames (the dark frames for the light frames, which are most certainly different than the dark frames for the above flat field frames) with the same camera settings and temperature as above. Make 16 (more is better but impractical). So, if you have made 10 light frames, each 2min, 800iso, then do 16 dark frames, 2min, 800iso. You can take the camera off and cover it with the lid to avoid external light (protect the open focuser with a plastic bag), but do not warm the camera. The next are the bias frames. These are easy. Chip temperature does not matter, but iso speed does and time. A bias frame contains the glowing of the electronics at the iso setting. Ideally it has no chip information but that's not possible with a dslr. So just take the shortest possible exposure time and do at least 16 frames. Ok, to summarize: >10 lightframes, ~16 darkframes at the exactly same settings and conditions than the lightframes, ~16 bias frames at the shortest time and same iso setting as the lightframes organized as raw files on your harddrive in a matter that you do not mix them. Feed DeepSkyStacker with them ... If you still have a noisy background that is most likely from light pollution, which is not covered by the process, it fact it cannot be covered by any process known to me. I was not successful last night, i had to wait until after midnight and then a high veil of clouds came up. @_Augustus_: beautiful telescope ! Suggestions: Andromeda galaxy, open clusters, (young stuff for the kids), globular clusters (old stuff for the grown ups), Orion nebular, Venus in the evening sky (half venus on the 17th ?), a hike along the moons terminator line, structures in the grazing light are a fine sight.

The guidescope is an ed80/480, not an apo in a strict sense. The apo is a fine 115/805 tmb design with an lzos lens i got used from someone who gave up and the mount indeed is a g11 (no goto).

Aaah, i wouldn't be that apodictic about it, maybe the one or the other is that fast. It's not "press that button and it works automagically" but i have seen tracks of the ISS done with an upper class amateur mount, but it was tuned with special motors. The guy pointed just at the right spot when it came over the horizon. He used a 15.000 funds telelens, though. My jaw was still in the grass when he had long packed up :-) Main problem is indeed to point at the right spot at the right time, you have only fractions of a second when the station appears and if you loose it it's gone. I can imagine that something like that could be done with satellites too, but who cares, there are so many beautiful natural objects :-) But i think @Jonfliesgoats must find the right setup for "normal" imaging before doing stunts like that. Though i'd love to see the outcome :-) Edit: showing off my stuff with the brand-new ccd cam, set up for hopefully a successful shooting tonight: There is an assembly error hidden in the photo. Hint: it is not photographic :-)

Well, you could take a look at the documentation of Fitswork or PixInsight. Everything you do to flatten a picture or filter out noise lowers the level of detail. Not that much a problem with moon and planets but DSOs and nebulosities will suffer greatly. Yeah, well, amateurs do participate in finding new comets/asteroids, it so happens. But i fear that the necessary equipment exceeds the financial possibilities of most of us .... (well, it exceeds mine :-)).

Both, house and drive. The place here can be pretty dark but my neighbour loves nightly illumination. I did Andromeda from up the mountain and M45 from the patio. Will install something against the light to earn my reputation as a crazy foreigner . But first the weather must improve. In principle there is not much you can do. Lots of flatfield images, experiment with filters, post processing all may wor to an extent. Best is really to beat it and go to a dark and high place, for viewing and of course imaging.

Today this is the mostly used method to pick up an Ad-Banner. Less hazzle than towing the stuff over an airfield. After the war the method this was also used to start a manned glider out of a short meadow.

Well, meanwhile there are quite a few science papers that deal with the class of dimming stars. We can decide whether to play with aliens or get behind the dimming. This is no offense to nobody, just again the hint that we will not understand nature if we assume unnatural causes.

Absolutely. But then it's no more Science & Spaceflight but Fantasy & Fiction.

I do :-) Anyone else ? *curiouslylookingaround* RC is simply a type (one of the Cassegrain-types, that are those who reflect the rays back through the main mirror instead of out at the side like Nasmyths or Newtonians) where two curved mirrors are combined in a way to reduce coma and aberrations in the picture's field, that is away from the optical axis. Most of the large telescopes are RCs because they combine an easy handling of the weight involved and offer a basically corrected field. Most have several focus points (2*Nasmyth, 1 Cassegrain-style) for a whole lot of different instruments, cameras, spectrometers, sensor phalanx, that sort of things :-)). Of course one wants to have as little optical elements as possible, the usual way of building long focal ratios is by folding the rays multiple times. I don't know how many mirrors the GTC has (at least three) to get to its focal length of 170m. Diameter of the central obstruction is a construction element. It makes the image a little darker, but it must obstruct 50% to cost one focal ratio unit .... Oh, btw., the new E-ELT will have a focal ration of 0.9. I don't know about the TMT, but probably something alike ...

Yeah well, i watched the first few minutes then quit because it is mainly fiction (movies, fantasy), no facts. Btw., just a few days ago i watched Metropolis, the b/w-movie the first scenes are from. So much for my thoughts on the video. I suggest we define intelligence, sentience, consciousness and self-awareness on a supra-wikipedia level. And get an understanding of what the soft voiced speaker means by "human level". How do humans perceive, understand, what are the cognitive processes and can they be modeled into (very complex but still) algorithms ? Are there any pre- or early stages of cognitive processes ? How can they be identified ? What is the actual state of AI in computer science ? Discussion from the 90s: Is a very good chess program AI or just a huge library with a sophisticated algorithm ? Is a car that finds its way without a driver intelligent ? On the other hand, is a driver holding a wheel and driving from a to b doing anything "intelligent" ? He, who steps out of the window ?

Very sad that. Maybe someone has the idea to name an asteroid after her. btw., off topic, but Rick Parfitt died as well a few days ago. And if you don't find someone else then i can help with the active volcano ...

Hi, thanks all for the help. The typo b instead of n probably happened when the forum editor added the link automatically when i typed it but didn't correct the link when i backspaced and corrected my typing. My router isn't clever enough, but it is behind the providers router (special satellite thingy) that i have no information about. Now i had to learn first what ad/pr0n means. I doubt it, but i didn't try it out. At least not willingly, if you know what i mean :-). Up to now i never had a problem with ssl-connections and this is the only site that doesn't work (that i now know of ...). I would guess that a proxy i wasn't told of is in the way. I have no vpn-software (read: knowledge :-)). And i sadly have no outside ssh server i could tunnel over ... Looks like i'll have to do the communication with that site from out of the pub. Until terrestrial internet finds a way to my place.

Hello steve_v, thank you for the quick reply. So get a page not found ? Well, i even installed a brand new Ubuntu 16.10, without any changes, the page will not load. https://sanitas.es does not load, connection reset, www.sanitas.es loads without styles and resources (pictures, etc.). No proxy in my network. Will try with the tablet from one of the bars in town ... Edit: works outside. must be a problem of the provider ...