Alex Pratt

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Viewing 20 posts - 241 through 260 (of 306 total)
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  • in reply to: A most unusual meteor spectrum #579958
    Alex Pratt
    Participant

    Hi Bill,

    The meteor was also recorded by Andy McCrea (Bangor, NI). He and Michael O’Connell analysed his video clip. My single-station analysis was a good match for a Perseid, but our 2-station result suggests it was a sporadic of absolute mag -2.5 from a radiant in northern Cam with a Vg of 50.6 km/s.

    Its short path length of 12 km and our non-optimal viewing geometry only give a Q1-quality solution, so there’s some uncertainty in its computed orbit. I’ll let you know if more data are forthcoming.

    Clear skies,

         Alex.

    in reply to: A most unusual meteor spectrum #579946
    Alex Pratt
    Participant

    Hi Bill,

    My Leeds_N camera recorded a mag 1 Perseid matching the time of your spectrum. I’ve attached the composite image from the video capture and its ground plot. Does this alignment agree with your general azimuth?

    This is a single station result, so if other cameras recorded it we should be able to confirm its shower membership and orbit, etc. I’ll let you know.

    Cheers,

         Alex.

    in reply to: George Alcock Exhibtion at Peterborough Library #579750
    Alex Pratt
    Participant

    That’s a great idea for an exhibition, Denis. Let’s hope comet 21P puts on a good show in late August / September for young (and old) astronomers alike. If it brightens sufficiently they might not need a special yellow telescope to see it.

    Clear skies,

         Alex.

    in reply to: Unusually slow triple peaking meteor #579656
    Alex Pratt
    Participant

    Hi Andrew,

    Meteor cameras occasionally record long duration, long pathed meteors that exhibit interesting variations in brightness. At the Winchester Weekend I showed an extreme example that was visible for 10 seconds with a ground track of nearly 500 km, recorded by several video cameras.

    Such objects are usually in Earth-grazing paths, skimming the atmosphere and their solar system orbit is such that they are catching up with the Earth, rather than a head-on collision.

    I’ll ask the NEMETODE video meteor network if anyone recorded your object. Multi-station captures can give us a ground track and solar system orbit, then we can evaluate the event.

    Clear skies,

         Alex.

    in reply to: Russian Fireball #579646
    Alex Pratt
    Participant

    They are good quality recordings of these impressive events.

    Yes, as well as Russians never leaving their driveway without a dashcam they are becoming increasingly popular in the UK because of ‘crash for cash’ scams and irresponsible drivers scarpering from incidents, such as low-speed shunts.

    It could be a while though before the BAA Meteor Section needs to appoint a Dashcam Fireball Coordinator…

    Clear skies,

         Alex.

    in reply to: Liquid crystal shutters for meteor observing. #579559
    Alex Pratt
    Participant

    Hi Bill,

    It will be quite a bit of work to replicate Steve’s meteor analysis techniques from 20 years ago, but you should have a lot of fun in the process.

    I’m considering changing my Leeds_N lens from a 12mm to an 8mm, to increase my coverage of the Borders and southern Scotland. This will increase our chances of recording more dual- and multi-station events.

    Heavy snow put paid to my attendance at the ASE meeting in March so it’s been rearranged for October 5th. I’ll be in Edinburgh for a couple of days. I’ll keep you updated.

    Cheers,

         Alex.

    in reply to: Liquid crystal shutters for meteor observing. #579555
    Alex Pratt
    Participant

    Hi Bill,

    The longest focal length lenses in the NEMETODE network (12mm) can achieve reference star O-Cs of 0.5 arcmin, very similar to the CAMS and SonotaCo networks. HD video systems should surpass this, but they need beefy PCs to cope with the data bandwidth and data processing requirements.

    Both SD and HD video systems have their uses in estimating meteor rates, radiants and solar system orbits. Let’s see what your DSLRs can do this summer.

    Cheers,

         Alex.

    in reply to: Liquid crystal shutters for meteor observing. #579550
    Alex Pratt
    Participant

    Hi Bill,

    Have a look at this JBAA paper by Steve Evans -1998 Aug Vol 108 No 4 pp. 204-206

    and other references to stepper motor rotating shutter systems

    1999 Dec Vol 109 No 6 p.300
    2001 Feb Vol 111 No 1 p.33
    2001 Dec Vol 111 No 6 pp.337-338
    2002 Apr Vol 112 No 2 p.63 & p.94
    Cheers,
         Alex.

    in reply to: Liquid crystal shutters for meteor observing. #579544
    Alex Pratt
    Participant

    Hi Bill,

    Great to meet up at Stirling!

    As discussed offline, I’m really pleased that you’ve got Steve Evans’ rotating shutter system up and running for long-duration operation. All members who knew Steve will be delighted to see any results you obtain with this kit.

    Perhaps we can locate a paper or report by him documenting its chop rate etc., although I fully agree with the need to check and confirm its current performance.

    Have fun!

         Alex.

    in reply to: Liquid crystal shutters for meteor observing. #579525
    Alex Pratt
    Participant

    Hi Bill,

    I have one of the late Steve Evans’ stepper motor-driven rotating shutters from AWR Technology. He used this system with Canon T70 cameras – and in conjunction with video timings from Andrew Elliott and Tim Haymes et al – determined the solar system orbits of Geminids and other major showers. It’s much easier these days using video cameras and the latest software!

    I’ve just tested the control box, stepper motor and cutaway shutter and it burst into life. The AWR Technology website describes this equipment, which might differ slightly from the items in my care.

    You are welcome to have them for your ‘olde fashioned’ meteor work. I can bring the items to Stirling this weekend.

    Cheers,

        Alex.

    in reply to: Units in astronomy #579511
    Alex Pratt
    Participant

    To add to the fun I once saw a ‘correction’ made by an editor (non-BAA) who changed all references to Angstrom to Armstrong.   🙂

    Clear skies,

         Alex.

    in reply to: New book on The Moon #579506
    Alex Pratt
    Participant

    Hi Bill,

    I must add this to my library. Any chance of it being available from the BAA Shop?

    Clear skies,

         Alex.

    in reply to: 2010 WC9 #579490
    Alex Pratt
    Participant

    David,

    thanks for posting about this brief opportunity to see this NEO from the UK.

    I find it frustrating and amusing in equal measure that the MPC’s ‘Daily Minor Planet’ often tells us about NEO flybys the day after they’ve been and gone.    🙂

    I had to smile this teatime as I checked my e-mails and ESA’s 2010 WC9 Close-Approach Fact Sheet arrived in my Inbox at 16:09. Informative but no use for planning a UK observing session.

    Thankfully other resources such as the Minor Planet Mailing List and some astro magazines tell us in advance. I recorded 2010 WC9 last night and will add something to my Member Page this evening.

    Clear skies,

         Alex.

    in reply to: Double peaking meteors. #579459
    Alex Pratt
    Participant

    Hi,

    It looks like my NW camera recorded the same event, although the meteor was near the edge of my FoV, so unfortunately I only recorded one of the trails.

    Cheers,

         Alex.

    in reply to: Nova in Perseus #579430
    Alex Pratt
    Participant

    We’re all likely to produce unintentional typos after a long observing session! 

    I used my Watec video camera and 50mm f/1.7 Vivitar SLR lens to record the field of V392 Per. I’ll add a pic to my Member Page later this weekend.

    Come along to Newcastle tomorrow. My talk won’t be flawless but I hope there’s something in there of interest.   🙂

        Alex.

    in reply to: Nova in Perseus #579426
    Alex Pratt
    Participant

    On Denis’ Member Page entry for May 2 a typo describes V 392 Per as a ‘comet’, so keep observing!     🙂

    Clear skies,

         Alex.

    in reply to: BAA Journals and Handbooks – offered for free #579330
    Alex Pratt
    Participant

    Hi Ian,

    Many thanks for expressing an interest in these items. My message was posted last year and I should have updated it because all the Journals and Handbooks have now found good homes, such as with the BAA Archivists.

    I noted in the For Sale column in the 2018 February Journal there is a set of Handbooks on offer.

    Alternatively, as a BAA member you can download PDF versions of the Handbooks and Journals via the Publications – Downloads tabs on the BAA website. Another option would be to purchase the BAA Journal Archive on DVD from the BAA Shop.

    Clear skies,

         Alex.

    in reply to: Ooops! #579247
    Alex Pratt
    Participant

    …and this 6th mag ‘nova’ was a ghost image of Aldebaran…

    http://www.astronomerstelegram.org/?read=4513

    Clear skies,

         Alex.

    in reply to: Triton’s diameter from occultation timings #579225
    Alex Pratt
    Participant

    Jeremy, in due course all contributing observers should receive a copy of the Lucky Star team’s paper, perhaps a preprint. Depending on where it’s published we’ll have to see if general readers have to negotiate a paywall, although the key results should wend their way into the public domain.

    Ray, I’m just summarising the results of many observers. The real science will come from the work of Bruno’s team, hopefully revealing any changes in Triton’s atmosphere since 1989.

    Cheers,

         Alex.

    in reply to: Asteroid Occultations 2018, Jan-Feb reported. #579193
    Alex Pratt
    Participant

    Most observers of this asteroidal occultation have now reported their timings and the asteroid’s profile (derived from multiple chords) has been updated on Euraster (maintained by Eric Frappa). There’s still one or two reports to come in. There looks to be some discrepancies in the set of chords.

    I’ll add the shape profile link to the observation on my member’s page.

    Clear skies,

         Alex.

Viewing 20 posts - 241 through 260 (of 306 total)