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alan4908 last won the day on April 4

alan4908 had the most liked content!

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About alan4908

  • Rank
    Proto Star

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  • Yahoo

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  • Gender
  • Interests
    Astrophotography ! ....at the moment I'm concentrating on deep space imaging
  • Location
    East Sussex
  1. alan4908

    Refractor For Galaxy Imaging

    Well I'd like to give another vote for the Esprit 150, having owned one for a little while now, it gives excellent results when used with the appropriate camera. With my SX Trius 814 I achieve 0.7 arc seconds per pixel which I've found gives excellent detail on galaxy images. Since I'm into automated imaging and I also wanted the best possible focus, I also upgraded the stock focuser for a Feathertouch. Alan
  2. alan4908

    Deep Sky III

    Images taken with a Trius 814 and a Esprit 150
  3. alan4908

    Star formation and HH objects

    Thanks Peter - yes, the image annotation function in Pixinsight is very useful for object identification and is highly customisable ! Alan
  4. NGC7129 is a reflection nebula in Cepheus. What I found interesting is that it contains quite a few Herbig Haro (HH) objects. These are formed when high speed narrow jets of partial ionized gas ejected by proto-stars collide with nearby gas and dust. The LRGB image below represents about 10 hours integration time and was taken with my Esprit 150. Approximately 500 HH objects have so for been discovered, so in order to see how many of these within the image, I decided to create an annotated image in Pixinsight via a HH custom catalog. I was quite surprised to discover that I managed to capture 11 HH objects in a single image, although some are a little more visible than others.... Alan LIGHTS: L:12, R:15, G:12, B:18 x 600s, DARKS:30, BIAS:100, FLATS:40 all at -20C.
  5. alan4908

    One for any electronics experts

    It really depends on your camera and the temperature. For instance with my camera (SX Trius 814) which has a low thermal noise + I capture all my flats at -20C, you have to be careful not to increase the noise by subtracting darks. In my case for flats, the signal is very high, so I choose not to subtract the dark but rather I subtract the bias. However, for my light frames which can go up to 1800s, the signal to noise can be quite low, so I do use dark frame subtraction generated from 1800s Dark Masters. To reduce noise, I use adaptive subtraction where the where dark scaling factor is determined by overall noise minimization rather than time. Alan
  6. alan4908

    One for any electronics experts

    OK I understand. However, why don't you simply take a sufficiently long exposure each filter ? For instance, for me this is a fraction of a second for my LRGB filters and it rises to 60s with my S NB filter. Alan
  7. alan4908

    One for any electronics experts

    Hi DP On more fundamental issue - I don't understand why you are contemplating using a UV light source for flat fielding. An EL panel will allow you to correct for dust donuts and vignetting. The fact that an EL panel has a poor response at your filters peak response is irrelevant since it is the dust and system vignetting that you wish to correct, not the wavelength response of the filters. Alan
  8. alan4908

    An open cluster and a reflection/dark nebula

    Thanks for the comment Wim Yes, this area doesn't seem to appear often on SGL. Alan
  9. The following LRGB image is of the open cluster (NGC225) and a reflection/dark nebula complex known as VdB4, both are located in Cassiopeia. I struggled with processing this image since it was contaminated by scattered light from an out of field of view star. However, after a somewhat extreme application of DBE and a bit of PS clean up, the result is below. This represents just over 10 hours integration time and was taken with my Esprit 150. Alan LIGHTS: L:21, R:15, G:12. B:13 x 600s, DARKS:30. FLATS:20, BIAS:100 all at -20C.
  10. alan4908

    Creating a hot pixel map

    Hi Peter Yes I would. It is not cheap but the amount of quality information that you will obtain will be huge. I would also recommend his PS and Pixinsight tutorials. Alan
  11. alan4908

    Creating a hot pixel map

    Hi Peter I also use CCDstack for calibration and stacking. I follow Adam Block's advice for hot pixel removal (the details can be found here: https://adamblockstudios.com/categories/CCDStack). I've found this to be highly effective. After calibration but before stacking run the CCDstack hot pixel filter: 1. Go to Process->Data Reject-> select reject hot pixels from the drop down menu. Set the strength to be 2 (which is a mild rejection). 2. Apply to all the images. 3. Have a look at the rejected pixels and see if the strength is adequate or not. 4. When you are happy with the rejected result go to Process->Data Reject->interpolate rejected pixels. Apply to all images. I'd also suggest that you experiment with the cold pixel filter. Whether you need this really depends on your camera but it follows the same procedure as above. Alan
  12. alan4908


    Many thanks Peter. Yes the image does represent quite long integration time which I think you need in order to stand a chance of capturing the outer halo. Alan
  13. alan4908


    Thanks for the comment David Alan
  14. alan4908


    Thanks for the comment Ian. Yes, I was quite pleased how well the outer halo came out. Having looked at the image for a while, I now believe that the image looks a little better full frame - see below. Alan
  15. alan4908


    My first attempt at M57. I attempted to capture the extended halo by gathering some OIII and Ha data and then blending these into Blue and Red channels, respectively of an LRGB image. The image below represents about 21 hours and was taken with my Esprit 150. Alan LIGHTS: L:13, R:13,G:8. B: 10 x 600s; Ha:13, OIII:14 x 1800s. DARKS:30, BIAS:100, FLATS:40 all at -20C.

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