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Dave Smith

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About Dave Smith

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    White Dwarf

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    http://astrosnaps.co.uk

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    Male
  • Location
    Maldon, Essex
  1. At last I have managed a long session on this star without any saturation. This one seems much more symmetrical than normal HADS stars (steep rise and slower decline) Dave
  2. Good work Graeme. Any idea why the second one is more noisy even though it is brighter? Dave
  3. Thanks Graeme. See my response to Whirlwind. At least some good news, Patrick has been able to extract a period from the results which fits in with the previous pattern. Dave
  4. Thank you very much for your reply. My initial thought was that your possible explanation was not the reason because I had tested the signal strength at the beginning of measurements but then I examined the output file and found that a very large proportion of my readings were saturated but not at the beginning. It looks as if the sky became more transparent rather than high cloud appearing. It is a lesson learnt although rather severe to have two nights wasted due to the same error. I am rather relieved that the cause has been revealed. Without your post I would not have thought to check that out, so thanks again. Dave
  5. I was in two minds as to whether I should post this or not. I have decided that it is worth showing that everything does not always go smoothly with variable star photometry. This particular star has a period of nearly 5 hours and so to get a decent range requires most of the night. Recently the sky has been clear all night and day so a good opportunity to get results on this long period HADS star. Here are the results for the first night, Sunday night 22/23 March 2020. It started well but then YUCK. The comparison star plots also showed increased noise. There was a little mist that night and so I put it down to that. The next night was also clear so I repeated measurements on the same star. Equally YUCKY !!! That night there was no cloud (that I could see) and again no jet stream. Wondering if it was a software problem I did the analysis again using MaximDL but it gave the same result. By the way, in both cases the exposures were for 60 seconds binned 2x2. Last night was also clear but I couldn't face doing it again so I had a play with the guiding of my scope. So far with variable stars I have not used guiding with my EQ8 mount but there is a very slow drift which I wanted to eliminate, although not urgent for my variable star work. Ho Hum I do need a good night of readings. I have not submitted the above results to the BAA or AAVSO. Dave
  6. Well done Graeme, keep up the good work. This is the first HADS star I ever tried but at that time was unaware of the project. I have spent two nights this week on V467 Dra which has a very long period but unfortunately the seeing/transparency must have been rubbish as the results after a short decent period were very scattered. I did submit them to Patrick but I guess he was unable to get the period as they haven't appeared on his chart. Dave
  7. Thanks. I would agree with that. I have also observed this star twice now and nothing like that on the first occasion. Dave
  8. I think you are probably right Andrew. It is too short for an exoplanet and the magnitude drop is too big also. I have tried to confirm that it is local cloud by looking at the light curve of all the nearest stars but none show the dip? Whatever the cause I don't think it is anything to get excited about. Dave
  9. At least this virus does not stop us going into the garden to do some astronomy. This was from last night. Any suggestions about the small dip in readings about half way through. The comparison stars did not show any variation at that time. Dave
  10. Thanks very much for that. I will post the results of your XY LMi in your thread. Dave
  11. I tried minima2.7 on this data and it produced a result very close to the predicted value. I'm not sure that Peranso can deal with just one set of results, I will check. So far I have only used it when I have data from different occasions to make a phase diagram and then an accurate period. I will have a play and see what is possible. I would be very happy to share data if it works. Dave
  12. Thanks Andrew. Not quite trial and error. From the quoted magnitude of the star I guessed an exposure from previous experience and then in AstroImageJ tested a sample image to get a profile of the star mainly to check it is not near saturation. After that I just had it running continuously to get as many images as possible in the time. Dave
  13. To have a change from HADS stars as it was clear yet again last night I thought I would try an eclipsing binary. This one was occurring at the right time. It also gives me an excuse to try out the Minima software suggested by @coatesg The predited minimum was at 22.33 UT Now off to play with Minima. Dave
  14. We've had a nice run of clear nights. 5/7 The night before last (Sunday) was to some extent wasted as I had stars rather too close to saturation and so unreliable measurements. I repeated them again last night with much better result. Dave
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