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coatesg last won the day on May 11 2018

coatesg had the most liked content!

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About coatesg

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  1. Another HADS star from the study Dave has introduced to me - new V filter in place now as well. GSC 03004-00870 in UMa. Quite a non-descript field, and had to again go hunting for reference stars using the APASS v9 photometric catalogue - everything here is over magnitude 12... Curve looks OK - instrumental flux steadily dropped throughout the evening - suspect I might have had a little misting of mirrors, but good enough for the result. I must connect up my secondary dew heater...
  2. Yep - without the two refs at the top, I can change the y-min, which will emphasise the curve. Interesting to prove why the right amount of signal results in smaller error bars (Poisson noise, etc)
  3. OK - sussed it out. Here's the calculated magnitudes with reference star names (NB: errors in APASS DR9 magnitudes aren't included here). Here's the field - the whopping diffraction spike is from Mizar, about 1.2 degrees away....
  4. I've had AIJ working before with abs mags, but not now! No idea at present! It's interesting work - last night if imaging, I would have been swearing that I set up, and then only got an hour and a bit of data... but that might well be enough for a meaningful contribution here
  5. Graph is plotted from AstroimageJ - I make the master flats and darks in PI, then use AIJ for reduction and analysis. @Dave Smith has a good tutorial pinned in this board! This looks like a fairly typical Delta Scuti curve - asymmetric in appearance, though you're right in that it is a rapid climb over >0.4mags.
  6. A run at capturing V416 UMa this evening, which is a short period HADS (~1.52hrs) - it's a faint one (mag 13.9-14.5 from my results) and I wanted to have a go at using the G filter and see what kind of exposure is required for this kind of magnitude star. (I have a Johnson V but haven't had chance to take the FW apart to install as yet and to refocus the OAG as a result) I ended up using 120sec exposures - it'll be interesting to see if this is fine enough to use for timing studies (will await feedback...). Using the APASS DR9 figures for the check stars (from VizieR), I get reasonably close figures, so think that the exposures are about right given the lack of brightness for this one - just whether the timing is good enough. (For some reason I can't get the absolute magnitudes out of AIJ to plot - not sure why?) Shame the clouds rolled in at the end and prevented me from getting the rise back to maximum to complete the whole cycle - I wasn't that far off...! (the points at the end of the run go completely haywire as a result of the decreased and variable flux).
  7. coatesg

    V799 Auriga

    Very nice result Dave - you had a really good run at that and got a nice result over a good number of periods! The range I get with unfiltered is slightly broader, but only at the minimum and then only by 0.02mag or so...
  8. coatesg

    V799 Aur

    Thanks Dave - yep, I'm less concerned about the autofocus routines now - it can be an issue on this scope if there's significant temp changes, but last night started cold and stayed that way! Very interesting shape, hopefully can contribute this data to the HADS work when I hear from Patrick.
  9. Preliminary results from a 3h40m run on V799 Aur last night - this is a HADS star with period 1.83 hrs. Autofocus had a slight blip in the middle where there's an 8 min gap or so, but got the period, and the slightly odd shape nicely. AIJ complained about the red ref star - need to check saturation levels on that. These were all 7sec exposures - unflitered exposures need to be so short, even at mag 10.something to stop saturating the stars!
  10. coatesg

    M42 in RGB and Ha

    Yep - superb result Peter. Those Powys skies are truly great when it stops raining (My wife comes from nr Newtown - when we used to visit her parents, it rained every single time, except once when it snowed! )
  11. Thanks both - yes, very pleased at the data (despite just missing the eclipse minimum!) - also quite surprised that I could drop to 10s exps and still be mid histogram exposure-wise - guiding is fine for 5min on this setup, but my word, much less hassle at <1min! Also, with a reasonable size aperture, my range of magnitudes isn't too limited. @Dave Smith I had had a go at doing the spreadsheet, but it didn't want to play ball very well. But, now think I figured out where I was going wrong (and how to adjust AIJ to get the right FITS headers): so I think I have a first draft copy of the results spreadsheet - would you mind giving it the once over before I think about submitting - assuming I'd need to request observer codes from BAA/AAVSO to submit? (I should also get round to joining the BAA at long last..) Thanks - that's super! I'd be very interested in getting involved in the HADS work - if you could introduce/pass on details to Patrick, that would be great! HADS studies, along with the other time resolved work appeals strongly, as it's possible to get results on the few occasions we have enough clear skies! Cheers!
  12. Back on Sunday night (27th Jan) I managed to have my first go at doing some CCD observation of variable stars. I haven't got any photometric filters (yet) but thought I'd have a go to make sure I've got the right idea, try out software etc. I tried it out on HL Aur (Beta Lyrae eclipsing variable) - unfortunately, I just missed the primary minimum due to equipment fiddlings (autofocuser + USB, sigh...) but I did get the rise out of eclipse. Equipment: ST2000XM, 14" f4.6 Newtonian. Images were 10sec each (the gaps are from focusing runs). Here's the AAVSO chart: I used the stars marked as 128 and 112 as reference stars (pink/orange), plotted out of AstroimageJ: Just need a suitable night and star to try and capture a full eclipse now (or may try for a HADS type star) - appears that if you thought choosing Deep sky targets was bad, this is a whole world more tricky! Then follows all the rest of the calibrations, etc. Have a lot of reading to do before I'm in a position to start submitting data. Oh, and error calcs....!
  13. I'd say this is the filter wheel not being in the same position for the flats as for the lights - the light and dark edges to the dust bunnies at the bottom of the frame is symptomatic. The only other thing (but seems very odd) would be if the light had been registered (thus shifting position) before reduction, but not sure why this would ever be the case...
  14. coatesg

    Canon 200mm F2.8L

    Use this with a QHY163M - fov is about 6 degrees on the long side. You'll get a bit more with an APS-C sized sensor. Found it needs stopping down to about f4 for sharpest edge stars.
  15. coatesg

    Petavius and Langrenus

    Have just got myself a TV Powermate to use for planetary imaging - managed to ave a first run on the day after it arrived (!). Typically just after full moon, so had to go skirting down the western limb - Petavius and Langrenus. The seeing deteriorated a bit after Petavius but fairly happy with the result. 350mm f4.53 newt, TV Powermate 2x, ASI-120MM, best 5% of 7000 frames. Petavius Langrenus

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