inFINNity Deck

Hi Jeff, Nice images, what scope did you use? Only that Earth is somewhat large. The Sun's radius is 696340km, the Earth 6371km, a ratio of 109:1. In your image the radius of the Sun is approximately 1000px, the Earth approximately 50px, which is a ratio of 20:1.... Nicolàs

According to Edgar Dutra Zanotto glass does not flow, see E.D. Zanotto, 'Do cathedral glasses flow?', in: American Journal of Physics, 66(5), (1997), pp.392-395. His conclusion was: Nicolàs

Forgive my ignorance, but can you perhaps explain how this MLPT takes into account changes in refraction during a whole night of unguided imaging (i.e. changes after this MLPT is done)? Thanks, Nicolàs

Hi Dan, not sure what your actual thoughts behind the question is. Are you considering getting one yourself or are you just wondering about these figures? Anyway, I do have a GM3000HPS in my observatory with some 60kg of equipment on it, consisting of five scopes, the main imaging scope being a SkyWatcher Esprit150ED with a focal length of 1050mm. To be honest I do not look at the tracking figures, all I care about is more or less round stars, so when it looks right, I am happy (I do not even bother to measure them). Yes, there are shortcomings even on a mount like this and I had a fair share of trouble with it over the past five years and only after one swap and a hardware upgrade after that it started performing to my liking. Having that said we need to keep in mind that there is no perfect mount around, see this review: https://www.macobservatory.com/blog/2022/12/30/a-comparison-between-the-astrophysics-mach2gto-and-10micron-gm1000hps-telescope-mounts Last year I considered switching to ASA myself (DDM100), but found their response to my question about the option to interface a weather station rather unsettling as to their opinion that this is not required at all. With my GM3000HPS the modelling RMS went from 9 arc-seconds to 5 arc-seconds thanks to the use of a weather station (measured over 74 plate-solves), so weather stations do improve performance on these mounts. When using long focal lengths it is best to do hybrid guiding, a method where guide commands are issued only once per minute to ensure the mount stays on track. This seems to work best from what I read on the 10Micron owners forum (which sadly is only open to owners). So far I have stayed away from guiding, only used it a few times to measure drift when I had issues. Using an SCT or RASA for unguided imaging is asking for poor performance as a significant number of these scopes have serious issues with mirror stability. I think in general people buy these mounts as they are so very easy to use, do high speed slews (up to 12 degrees per second), can do unguided tracking of any object whose ephemeris is known (programming them is a breeze), and can handle even more payload that officially is stated. Besides, it is just an awesome looking mount (but that is my biased opinion). If you want to see unguided images taken at 1050mm focal length with the GM3000HPS: http://www.dehilster.info/astronomy/nebula.php http://www.dehilster.info/astronomy/galaxies.php Currently I use 7 minutes subs for narrow-band to be around the optimum S/N ratio for my equipment and location, and I have successfully done 20m unguided exposures, but at those long exposure times success is not guaranteed. Nicolàs

That is a good question. All we know is that his are the earliest surviving recorded telescopic observations of the Moon. It could well be that Hans Lipperhey, Jacob Metius or even Prins Maurits, King Hendrik IV, the archduke Albert of Austria or the Pope in Rome (these gentlemen had telescopes within six months after Lipperhey's demonstration of it, well in advance of Harriot and Galileo) pointed a telescope at the Moon. But as no record of such observations by them survives, we assume that Harriot was the first based on his surviving observations. Nicolàs

Today I gave APP 2.0.0 beta 13 a try. What I did was as follows: – First stack on the comet, so with Registration Mode on Comet/One Star, and with Integration set to a Median Filter with Kappa High to approximately 1.5. This produces a sharp comet with no stars. I will call this [Plate 1]. – [Plate 1] still shows some vague traces, but these can easily be removed with a clone brush. It took me about 5 minutes to clean [Plate 1] a bit further. – Then stack on the stars with default settings, resulting in a starry sky with a smeared comet. This is [Plate 2]. – Pass [Plate 2] through APP's Star Removal Tool, which results in a star-less smeared comet. This is [Plate 3]. – Ran all three plates through Topaz to reduce the noise, but above all to reduce the artefacts left over from the Star Removal Tool, otherwise they will reappear later when combining. – Load [Plate 3] as a new layer on top of [Plate 2] and set this layer to difference. With this we subtract the smeared comet from [Plate 2], leaving a clean starry sky. This is [Plate 4]. – Load [Plate 1] as a new layer on top of [Plate 4] and set this layer on screen, so that the two layers are combined. This is [Plate 5]. – Then edit [Plate 5] as a normal deep-sky image until it is to your liking. The end result is what you see here: When enlarged it becomes visible that I followed the comet and used a too long shutter speed, so the stars are slightly oval. This can be prevented by using shorter exposures and more subs. The background also shows some streaks in the direction of the comet's orbit. This could be reduced with some extra cleaning of [Plate 1]. The question is, of course, whether this is a good representation of reality. The integration took almost an hour and the comet is now approximately where it was halfway through that period, but whether this is actually correct is questionable. For this plate one might as well combine [Plate 1] with an image of the same part of the sky taken at a later date, then the stars can be much rounder. Nicolàs

True, but I am not allowed to mention GG.... 😉 So, here is my 123: 1: Hans Lipperhey (first functional telescope, 1608) 2: Thomas Harriot's telescope (first telescope used for lunar (1609) and solar (1610) observations) 3: he who should not be named (first telescope used to observe the Jovian Moons, 1610) Nicolàs

Hans Lipperhey's telescope (1608). Nicolàs

I do have APP, so I could give this a go. Thanks! Registering and stacking on a comet is a breeze using APP (once you found how to do it): https://www.astropixelprocessor.com/community/comet-registration-and-integration/comet-registration-in-astro-pixel-processor-1-083-beta1-video-tutorial/ The latest APP has star removal tool as well. Later this week I hope to find some time to test the star removal option in APP to see if it is possible to create a comet image with round stars using only APP and image processing software (I use PaintShop Pro). Nicolàs PS: the latest APP version has a lay-out bug as a result of which the comet nucleus selecting buttons disappear off-screen when using a pc with low screen resolution. Version 1.083 does not show this behaviour, but does not have the remove star option. I have reported this bug and hope Mabula produces a fix soon.

Here is a nice tutorial (never tried it myself though): I do use APP, but not the Starnet++ option, simply allow trails to show: Nicolàs

Same issue here: micro-lensing. Nothing much that you can do about it apart from using a different type of camera or avoiding these bright objects. Of course you could try to select the reflections and darken them. Hopefully one day someone writes a plug-in or stand-alone program that can handle these reflections.... Nicolàs

It is better to state that the effect is imaging-chip related, as the QHYCCD QHY163 and ZWO ASI1600MM (and many other models) use the same Panasonic chip from the MN34230 family. It is due to this chip and the protective window in front of it that the reflections occur. As @The Lazy Astronomer wrote, there is nothing you can do about it, apart from using a camera with a different architecture chip (or to remove the window 🤪... no, don't do that). Nicolàs

This is a very clear example of micro-lensing, see https://www.cloudynights.com/topic/635937-microlens-diffraction-effect-explained/ Nicolàs

Then perhaps a crop of a raw file as a tiff? Nicolàs

Hi Grierson, it is difficult to tell from this image as it is heavily clipped on the dark side, but it appears to me as pinched optics. Can you upload a raw image file? Nicolàs

Here is my 10Micron GM3000HPS with some scopes attached (Esprit 150ED, Esprit 80ED, C11 EdgeHD, Lunt LS80THA, 30mm f/50 Galilean type telescope). Side-by-side plate (8") and 8" PlaneWave-clamp by Baader. Counterweights are 20kg each. Nicolàs

Higher gain indeed results in more noise, which in turn can be reduced by stacking more images (if available). There is some correlation between Exposure time and frame rate, but at very low exposure times frame rate mainly depends on data speed and ROI size. So going from 5ms to 3ms may increase the frame rate, but most likely it will remain the same (it does limit to about 200fps on my set-up. Nicolàs

Processing should not be complicated at all. What I do is as follows: - Record LRGB data (I image in mono) with FiraCapture at a as short possible exposure time and as high possible frame-rate. Usually I set my gain at somewhere between 250 and 300 and histogram filled to at least 40%. - Stack with AutoStakkert! using only (but all) those frames that raise above the 50% quality index. Enable sharpening and set Raw Blend to 30% for the ASI174MM, 0% for the ASI290MM. - sometimes I use WinJupos, but not always, in which case I do the following step: - RGB-combine in PaintShop Pro and adding the L-data as luminance layer (which is then merged). - Slight colour correction to ensure the background is black (not red as in above Jupiter). Usually this means I have to lower green by about 5-10%. - Add a little bit of saturation. (sometimes I reduce noise using Topaz). Done. This is how above images where processed. So no wavelets, no sharpening other than what AS! does, no complicated stuff as IMHO every additional processing step will add artefacts and render the planet into an artificial looking marble. Main importance are collimation, focus, and seeing. Nicolàs

Hi Bluesilver, yes, it is quite confusing, and it is a pity that I am in the middle of an imaging project, so I do not want to open mine to check it out for you. I went back to where I found that diagram: https://manuals.plus/sky-watcher/esprit-150-ed-super-apo-3-element-ed-apochromatic-refractors-manual#axzz7pVHdakQL As you can see it is a messy site. What I missed, is that the diagram is of the reducer/flattener instead of the flattener... So we have to ignore that drawing. That means we are left with the images and diagrams of other flatteners, and those seem to be "scope ( ( camera". Now, I do also have an Esprit 80ED with flattener on my rig (which is not being used at the moment), so I opened that one and that confirms "scope ( ( camera". But it would be good to compare what you create from your parts to that last flattener-photo I posted. Nicolàs

I have checked several drawings of other manufacturer's flatteners, and the first and last element should be convex in the same direction: In the last of above images a faint reflection on the uppermost surface can be seen, indicating that indeed that surface is nearly flat. But best thing to do is to mount the lenses and check if the reflections of and view through the lenses compare to the images in my first reply. Nicolàs

According to this image, the last lens before the camera is convex towards the camera: [PS: this is a diagram of the reducer/flattener, it comes from https://manuals.plus/sky-watcher/esprit-150-ed-super-apo-3-element-ed-apochromatic-refractors-manual#axzz7pVHdakQL] And the other side appears to be convex towards the scope: Here you can see what it should look like when everything is mounted. If you mount one of the lenses the wrong way around you may be able to see that it is different: I do have a flattener on my Esprit 150ED, but that is currently mounted with camera and all, so I will keep it that way... 😉 Nicolàs

Nice images Nigella! I think it is good for Beermaker and other planetary starters to know that most quality images we get presented are the result of many failures. It takes quite a few attempts before a good image is taken. A few tips: - Always use an ADC (unless imaging near zenith); - Always check collimation on a nearby star (unless imaging with a reflector); - Always focus (some do it visually on the planet itself, but I learned the hard way that using a Bahtinov-mask on a nearby star or planetary moon works easier and better); - Always take multiple runs (seeing can change in a matter of minutes); - Do not expect every imaging session to result in a good image. Here is how I started four years ago (C11, 2x PowerMate, ZWO ASI174MM): And this is now, still using the same equipment: Still I have plenty recent examples that look nothing like this and that is what seeing does to your project... Nicolàs

Part II of that page is especially of interest as it explains in great detail the aberrations you can expect (it is link to at the bottom of Part I). Nicolàs

ADCs are very effective and a must have for obtaining good planetary images, even if imaging is done using a monochrome camera. The filters (whether they are embedded as a Bayer-pattern, or sit in a filter-wheel) have a band-width of about 100nm per colour. Suppose we image a planet at 40 degrees altitude, then the light coming in through a blue filter (400-500nm) disperses by about 0.7 arc-seconds, green light (500-600nm) disperses by about 0.4", and red by about 0.2". The PDS150 at f/15, combined with the GPCAM3, will image at about 0.3"/pixel, so in blue the refraction induced smearing is more than 2 pixels, in green this is more than 1 pixel and in red almost 1 pixel. Using an ADC this can be reduced to virtually zero. When we do nothing at all in the processing, the smearing from blue towards red is at least 1.3 arc-seconds or 4 pixels (actually more like 1.5 arc-seconds or 5 pixels as blue starts around 380-390nm). When the object is lower the refraction increases significantly, at 20 degrees altitude the total smearing is more than 3 arc-seconds (some 10-11 pixels). Nicolàs

Hi Michael, if I draw straight lines in both images along the vanes of the spider, it indeed seems that the hub is drawn towards the focuser: It appears to me that the upper-right vane is more off than the lower-left one as if they are not in line with each other on the hub. The other two vanes look fine to me. Nicolàs