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About Whirlwind

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  1. Whirlwind

    IAS 2018

    The UK economy is struggling to maintain momentum with everything that is going on. Most evidence points to people prioritising food over other luxury goods (the store, but non-food, retail sector is in a complete mess). Hence I am not surprised that there is less attendance. Additionally things may also be normalising now the BBC no longer promote the previously high profile Stargazers Live series (which did gain peoples interest). I was intending to go myself on Saturday but other items got in the way.
  2. Whirlwind

    Which Frac

    It depends on your imaging priorities. If, imaging in narrowband, large nebulae are your focus then the 100 Esprit with a shorter focal length would probably be better. This smaller faster telescope and the high sensitivity of the SX694 will mean you can gather more flux per pixel than the SX694 on the Esprit 120 will do in the same amount of time. On the other hand if small galaxies/planetary nebula or general broadband RGB imaging is your preference and the wide angle is less of a concern then the 120 might be better as it will give you a finer pixel scale potentially assuming the seeing isn't terrible. The longer focal length and greater weight of the 120 will place more load on your mount. I have no experience with the EQ6pro; the 120 will place more strain on it's ability to track (and guide) accurately.
  3. Probably not if there are free trade deals with everyone as it will be difficult to compete against, even cheaper, manufactured imports. The only area would be to find a real niche area but how long until it is copied? If there was a larger market and less cloudy skies then possibly.
  4. Whirlwind

    What do you think this is?

    Cherenkov radiation perhaps? Comic rays hitting the atmosphere and releasing optical photons as they slow down. There are even telescopes designed to observe such features (e.g. MAGIC) I see similar star link brief flashes on the all Sky camera. These also look optical (same optical distortions because of the lens). Astronauts also describe optical flashes when in space. I've always wondered whether the mapping the position from the All sky camera might map certain locations that are known to be sources of high energy cosmic rays. An experiment for a future date.
  5. Whirlwind

    Narrowband filters and focal ratio

    The issue comes from that most (if not all) narrowband filters are interference filters. Because of the way they are designed I assume most are designed for light to arriving at the filter perpendicular to the glass. For slower systems this is close enough approximation. With faster systems this approximation breaks down and as the light travels through a larger amount of glass the interference effect starts blocking the preferential wavelengths and lets through, usually, more blue shifted wavelengths. If this shift is enough to block completely the desired wavelength (e.g. OIII) then you won't get any signal. Generally however it is shifted to lose some but not all so your signal is weaker. The wider the pass band on the narrowband filter the less of an issue this is. A better explanation can be found here:- https://www.edmundoptics.com/resources/application-notes/imaging/filtering-in-machine-vision/ I am surprised that a 6nm OIII and an F3.6 is giving such issues however. If you were using a 3nm and a F3 or faster system then maybe (but even then I've seen narrowband images using this set up as well). OIII and SII can be weak in some objects whereas Ha can be very dominant (general gas clouds for example). Remember hydrogen is the most dominant gas the universe, you should expect a much stronger signal from it. Maybe the signal is weak simply because of the observed targets?
  6. Hi A few things that might help identify your data. 1) Bin the data points (i.e. average an equal number, say 5 and average the result). Even professional raw observations can look a mess before binning. 2) Plot the comparison stars. A good indication of whether you have the transit is if the comparison stars show the same features (usually you divide the target star by the comparisons as that consistent effects) - Not sure if the software is doing this 3) Only plot the points (not lines). Lines are for spectra not photometry. Lines can lead your eye as to whether you have a feature or not.
  7. Whirlwind

    Cure for Aperture Fever?

    Maybe a stargazerslounge crowdfunding campaign. Almost 60,000 members £20 each should just about be able get one between us (plus camera, filters observatory, and resident astronomer etc). Assuming 30 clear nights a year of 8 hours equals 14400 minutes imaging time total. That's about 14 seconds each observing time a year, equivalent to £84/minute for observing. Bargain.
  8. Whirlwind

    Cure for Aperture Fever?

    Well they accept cash on collection...just in case!
  9. Just as a question but is there a preferential direction that ZWO filters are meant to set up within the filter wheel? I think reflections can be made worse if they are the wrong way round. However I have read that old ZWO filters had halo issues. According to a user review on cloudynights I saw the newer ones are meant to be better.
  10. Whirlwind

    Strange lines on images

    I would try dithering to see if it removes the features. If you have fixed pattern noise in your images why would you not expect to see it in an individual uncalibrated frame?
  11. Whirlwind

    Strange lines on images

    It might be walking floor noise. How well matched are your darks to the lights temperature wise (and the same for the flats?). How old is your master dark that was used the calibrate the image? Another example can be found here. https://www.cloudynights.com/topic/467758-fixed-pattern-noise/ You can generally dither to remove it, but I would check how well your calibration frames are matched to start with.
  12. Whirlwind

    Strange lines on images

    Do the bias and/or similar time length darks show the same feature?
  13. Whirlwind

    The Curse of the AN September Issue

    I think I can guess the answer - is it b) refractor?
  14. The examples were done with DSLRs though (and probably unmoddified). You have a much more sensitive camera. The DSLRs also have filters to restrict certain wavelengths, you have a white light camera. You can't really relate in the same way to exposure times. Try shortening your exposure times to 5 secs or even less. You want to aim for 16bit converted counts in the brightest pixel of no more than about 30,000 - 35,000 counts. Alternatively you could try a filter of some type to reduce the flux to a manageable level (or at least knock out far red/IR light).
  15. So I haven't seen this mentioned and if it has apologies. However Celestron have a new version of the RASA telescope coming out. This time in an 8" version. It appears it is more limited in that it has a smaller flat field of view (probably not a surprise given the smaller size). However one thing that has me more interested is that they've redesigned the focus mechanism. There has been a discussion on this on cloudy nights and if it works as well as is stated then it could be that the need for after market focusers would be a thing of the past as there is not meant to be any residual image shift. Although I tend to find the RASA limiting as I prefer narrowband observations it will be interesting to see whether they transpose the improved focussing system onto the Edge series. https://www.celestron.com/products/8-rowe-ackermann-schmidt-astrograph-rasa-8

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