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coatesg last won the day on May 11 2018

coatesg had the most liked content!


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  1. Three HADS stars from the night of the 14th/15th - YZ UMi is well placed for not having to move the dome at all at +85 Dec! V645 Ser, GSC2623-1174 and YZ UMi. All V filter on 350mm Newtonian.
  2. Indeed - I enjoyed it too (a welcome break from other stuff going on!) - thanks for putting it on! As a CCD observer, not two stars I'd often/ever observe as well
  3. Cheers! (More by luck after I nodded off, but probably got more data than I otherwise would have done )
  4. Currently in superoutburst (max light 16th April), V844 Her is an SU UMa type Cataclysmic Variable, and is displaying superhumps in the light curve with an amplitude of about 0.16mag. Captured from W Oxon, 151 x 90s, 350mm newt, ST2000XM, V filter (most of it after I nodded off on the sofa - luckily it is well placed to stay in the "slot" of the dome for almost all the session...)
  5. ER UMa is currently in superoutburst (it's fading from the max at about 12.5V and is currently about 13.4V). This is a peculiar sub-class of SU UMa type dwarf nova that has very frequent outbursts - somewhere around 43d between superoutbursts (see discovery paper: http://adsabs.harvard.edu/full/1995PASJ...47..163K). Last 2 nights I have managed to do some time resolved runs to try to record superhumps in the light curve. First evening wasn't great, and was affected by thin/passing cloud a bit. Last night was much better and allowed a much longer uninterrupted run I omitted the error bars from the ER UMa points to try and more clearly show the shape of the curve. 13-14/04: 14-15/04:
  6. ... was one of the most impressive auroral displays of modern times. I saw a bright red sky from Southern London with bright white streamers. It was visible as far south as Southern France. (I should fish out the prints from the loft! If you have photos please post them!) Remember this well as it was my 20th birthday at the time...! Another 2 decades older now!
  7. Managed to find a well timed minima of BS UMa to capture last night. This is catalogued as an EA type eclipsing binary with period 8.388237hrs, with almost exactly a 1hr rise/fall time. Looks like there's possibly some reflection effect from the "shoulders" in the curves. Minima timed as HJD 2458940.4271 +/- 0.0001 (calculated using Minima27). All images 30sec, V filter, ST2000XM, 350mm Newtonian.
  8. Based on the ephemeris "2452500.248 + E x 0.3153620" from the Krakow database (J.M. Kreiner, 2004, Acta Astronomica, vol. 54, pp 207-210.), the predicted minimum for epoch 20409 is: HJD 2458936.47106 - so looks like: O-C=+0.0085 - appears to be a bit anomalous compared to this O-C plot...: (EDIT; but appears to fit right in with Bob Nelson's OC data - no idea what's wrong here!)
  9. Managed to have a good 5 hour or so run on FV CVn last night - runs like this are going to become more inconvenient as the clocks change tonight and it gets darker later! Have an issue with tracking on the mount, which doesn't affect variable work so much, but there's an odd jump here or there in tracking - it may well be a balance issue (I'd tried to improve it and clearly made it worse!) - gladly for variables, it's not so critical as for astroimaging! Minimum measured as JD 2458936.4752 +/- 0.0001. (HJD = 2458936.4796) (All images were 60s, 350mm Newtonian, f4.6, ST2000XM, V filter)
  10. Declination of -2 so higher airmass, and our row of terrace houses forms an artificial horizon due south of my dome! Heat from the houses, central heating, open fires... not great !! (Also, the scales are different on the graphs - the second one only seemed to vary by <0.2mag)
  11. Quite a productive period at the moment third night on the trot! Another two HADS stars: V488 Gem and GSC 4935-0348 (ASAS J115229-0245.1). The latter looks quite symmetric for a HADS star - usually a much quicker rise than this. V488 Gem is in quite a busy field:
  12. Ah that's good - and the wrong way round compared to usual! I tend to shoot for 10-20k ADU which gives good headroom and space to drop while still having decent snr...of course it can always go to pot!
  13. A nice evening last night - dark and transparent - was able to get quite good data with relatively short exposures - here V1209 Her is between mag 13.4 and 14.1 - I started out with 3min exposures, reduced it to 2, and then (through a bit of an error) finished up with 1 min exposures. Even then, the error bounds are very reasonable. 350mm newt + ST2000XM, V filter. I did also obseerve V488 Gem - on the other side of the mount, and lower in the sky over the houses, the tracking and seeing was not so good. Still usable data - just need a sequence from the AAVSO at the scale I work at (26x19 arcmin)
  14. Yeah - high cloud (or worse, passing cloud that affects the comparisons and the target unequally) will definitely give weird results like this. It's usually right at the end of the period as well!
  15. Cheers! Sometimes Patrick does take a few days to put them on for me, but they generally appear eventually!
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