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Dave Smith

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About Dave Smith

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    White Dwarf

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    Maldon, Essex

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  1. I use an Atik 460Ex with a photometric V filter. I am sure however many CCD cameras would be suitable. One consideration would be the field of view to ensure enough comparison stars are in view. My main interest was once imaging so I do have a filter wheel with sufficient places to take LRGB and Ha,O3,S2 as well as the V. You can screw a single filter onto the end of a CCD camera so a filter wheel is not essential. I used to use an Atik 314 Both Atiks are low noise and I find it only necessary to cool to -10 degC . The chip of the 460 is double the size of the 314. By the way it is no
  2. Hi Steve It is better if the comparison stars are of similar magnitude to the target star if possible. I've just had a look at the aavso chart for S Cas and can see that it could be tricky. One of the brighter comparison stars have a few faint ones very close by. Dave
  3. Hi Steve The purpose of defocusing is to help insure that the star image, and the comparison stars are not saturated. I don't go out of my way to defocus but don't worry too much about being in focus. It is important that you check that it is not too close to saturation. S Cas has a very long period, you may find it more interesting to try a star with a short period so that you can detect change. Ther are suggestions on the BAA VS web site. Dave
  4. What mikeDnight has said is very relevant, You can alternatively study eclipsing binaries which have a regular periodic pattern so that you can get the full picture over a number of nights. I have mostly been looking at HADS stars that have a cycle of only a few hours and so it is possible to get one or more complete cycles in one session. See here for ideas https://docs.google.com/spreadsheets/d/1oGA2HaEHE8L6eX19ZoHqQQTu0LYV56HX3Srg7oCtOHo/edit?hl=en&hl=en#gid=883500896 Dave
  5. I've never done that as the stars i have been looking at vary quite rapidly. I was advised that for longer period variations to just submit the individual readings. Dave
  6. Hi Steve, I don't use that method at all. I get the comparison stars from aavso. If that doesn't work I get comparison stars from a star chart program "Guide" which has the UCAC3 star database. Usually the charts from aavso are sufficient. Personally I don't put the magnitudes in at the AstroImageJ stage but later when putting the data into the BAA spreadsheet Hope that helps. Dave
  7. Hi Steve. With SGPro it slews to where it thinks it should but then takes an image, plate solves it and then makes a correction. It will do this until target is in the centre as accurately as you choose. Dave
  8. I find that the plate solving facility in SGPro brilliant for getting the star right in the middle of the FOV. Dave
  9. Each point comes from one image. No stacking involved. Each image has to have darks and flats applied before any analysis. This can also be done in AIJ. Hooe that helps. Dave
  10. For a number of reasons I haven't been able to do any observing since the spring. Recently I did get out but unfortunately my scope would not go to the correct part of the sky. My target was just to the left of Mars but the scope kept on going to the right of Mars. It subsequently dawned on me what the problem was. My laptop had not done its usual automatic changing the clock to GMT. Once corrected all was fine. Since then I did have one evening where the results were rubbish and finally two successful nights. I had chosen stars in Cepheus to avoid interference from the Moon.
  11. You don't have to but it makes the analysis run very smoothly. With my images there is a small drift and so I have to make a small correction about every half hour to an hour and unless it is done manually the program will lose the star. Dave
  12. Thanks Steve. You could do that but it would be just as easy and more rewarding to choose a known variable and see some variation that you know should be there. What scope are you intending to use? Dave
  13. An excellent find Michael. Adding them to the BAA database could be very valuable. Dave
  14. Thank you all for your very nice comments. Roger has been my BAA mentor and I owe him many thanks for the guidance he has given me. Early on he introduced me to the HADS project run by Patrick Wils. I subsequently met Patrick at the AAVSO/BAA meeting in 2018 and have enjoyed participating ever since. Dave
  15. I have no excuse as this isn't the first time! Dave
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