Alex Pratt

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  • in reply to: Lunar occultation of the Pleiades Jan10.1 #627544
    Alex Pratt
    Participant

    I recorded 8 events last night. Temp was -6C and everything worked fairly well except that the seeing wasn’t good, especially when the Moon was at low elevation over neighbours’ rooftops.

    Running at 100 fps I didn’t detect any steps in the DD of Merope, Alcyone or Pleione, but Atlas displayed one of about 0.08s (attached). The Occult prediction gave details of Atlas’ multiple nature. Mag 3.6 Atlas has components Aa of mag 3.8 and Ab of mag 6.8, separation 0.22″, predicted step duration of 0.12s. It looks like Ab was occulted first.

    Tim – this weekend I’ll run it through Limovie and prepare a double star report and work through the other events.

    Great to get a clear night for M45 – but please arrange it for warmer weather next time. 🙂

    Alex.

    in reply to: Lunar occultation of the Pleiades Jan10.1 #627528
    Alex Pratt
    Participant

    Hi Tim,

    I have similar from my Alpine jaunts, just don’t wear them in the observatory to avoid perforating the cushion floor. I don’t think I’ll need the ice axe, unless it’s to prise open the door.

    This cold air brings lower humidity, 80%+ instead of 90%+. Windchill from the breeze though. 🙁

    Alex.

    in reply to: Lunar occultation of the Pleiades Jan10.1 #627526
    Alex Pratt
    Participant

    Thanks Tim,

    I hope to record some of the events as long as I and my observatory don’t seize up. The garden is sheet ice and snow compacted into concrete. Every time I unjam the door it freezes up again, the roll-off roof is in a similar state – and my dew shield has decided to fall apart.

    What could go wrong…? 🙂

    Alex.

    in reply to: Moon occults Saturn on 2025 January 4 #627396
    Alex Pratt
    Participant

    Congratulations, Lars!

    in reply to: Betelgeuse #627248
    Alex Pratt
    Participant

    Leona-Betelgeuse occultation – 2023 Dec 12 – pro-am campaign update

    Lead scientist Dr Miguel Montargès (LESIA – Observatoire de Paris) advises all contributing observers that the analysis of circa 100 light curves is proving to be an extremely complex process. They ask all observers and researchers to be patient during this work and Miguel gives us the encouraging words that the campaign’s results will be published in two (or perhaps even three) papers.

    Alex.

    in reply to: Fed up with cloudy nights try this #627090
    Alex Pratt
    Participant

    Be careful Bill, you’ll now be headhunted by GCHQ 🙂

    Alex.

    in reply to: Leonid meteor shower #626590
    Alex Pratt
    Participant

    Nov 17/18 waw clouded out here until 03 UT, then the bright Moon and hazy sky restricted my south-facing cameras. They captured up to 5 Leonids per camera; my north-facing cameras got twice that number. In conditions like that, the UFO cameras outperform the RMS ones.
    Nov 16/17 had variable cloud and recorded even fewer meteors.

    As well as Leonids, the sigma Hydrids were active, the trickle of Northern Taurids continued and a few alpha Monocerotids were detected. A clear sky (and without the blazing Moon) would have been quite productive.

    Alex.

    in reply to: Comet imaging help – C/2023 A3 #626155
    Alex Pratt
    Participant

    9. I suspect a DSLR is just not as “good” as a dedicated astrophotography CMOS camera.

    James,

    A DSLR can be used to get very good widefield images of comets, whole disc images of the Sun and Moon, and details of sunspots and lunar features. Your DSLR has a full-frame 14-bit sensor which can record a greater tonal range than a 10-bit sensor such as used in the Seestar S50, for example.

    I have some dedicated planetary imaging cameras yet it’s still fun to attach a DSLR to a ‘scope and get some nice ‘large frame’ lunar vistas.

    Alex.

    in reply to: Comet imaging help – C/2023 A3 #626118
    Alex Pratt
    Participant

    Hi James,

    Not a detailed workflow, rather the key steps to enable DSS to stack comet images. See Nick Haigh’s advice here:

    https://www.simplelists.com/baa-comet/msg/25949574/

    Alex.

    in reply to: Comet imaging help – C/2023 A3 #626113
    Alex Pratt
    Participant

    Hi James,

    You’re welcome. On the baa-comet forum Nick Haigh outlined the workflow in DSS for comet stacking. This is also what I use.

    To minimise saturating the coma yet bring out details in the tail you use the Luminance tab. Use your mouse to draw a box around its head and part of the tail, then gradually tweak the pairs of sliders for Darkness, Midtone and Highlight, each time clicking Apply to see the change – or Reset.

    This is finicky work – it’s almost a Dark Art – subtle changes in the values can make a big difference to the image.

    I’ve taken some screen shots of my steps in DSS, so I’ll retry comet stacking (stationary stars+comet option) and send you them (offline) in a PDF, either later today or tomorrow.

    Cheers,

    Alex.

    in reply to: Comet imaging help – C/2023 A3 #626109
    Alex Pratt
    Participant

    Hi James,

    I ran your darks, flats and lights through DSS, selected comet and stars tracking (star freeze effect) and got the attached image. It’s a pleasing view but it didn’t track the comet’s coma as well as I hoped. I’ll try it again.

    You had 6 darks and 3 flats. As Nick advised, you need double figures of those to create good master darks and flats. DSS does a lot of the work for you but if you have only a few darks and flats, and if the masters are not good quality, they can produce a final image which can be worse than simply stacking all the lights.

    Cheers,

    Alex.

    Attachments:
    in reply to: Seestar S50 self-help group #625935
    Alex Pratt
    Participant

    Hi Paul,

    I don’t have a Seestar but I found these presentations which might be of use, or at least of interest

    https://www.youtube.com/watch?v=vMCf7nFMQmo

    https://www.youtube.com/live/4BhlkOqo8cU?t=619s

    Alex.

    in reply to: Record breaking meteor spectrum #625866
    Alex Pratt
    Participant

    Thanks,

    I’ll look out for that.

    Alex.

    in reply to: Record breaking meteor spectrum #625860
    Alex Pratt
    Participant

    Hi Bill,

    Excellent results! Most likely a sporadic?

    Cheers,

    Alex.

    in reply to: coalition #625819
    Alex Pratt
    Participant

    Once again I will ‘enjoy’ Light Night Leeds

    https://www.lightnightleeds.co.uk/

    Alex.

    in reply to: Last night’s Aurorae #625705
    Alex Pratt
    Participant

    Hi Nick,

    The STEVE phenomenon looks like that and it usually lasts for several minutes. Ask Sandra about your event.

    I can’t confirm it on my meteor cameras but one of my north-facing ones recorded a very brief auroral ray brightening at 21:00:13 UT during lots of rapid changes (see attached). My full (mono) video from camera UK001H is here:

    https://youtu.be/I3g_A8WXDFY

    Cheers,

    Alex.

    in reply to: Equipment advice #625476
    Alex Pratt
    Participant

    Hi Gordon,

    Have a look at lockable garden storage boxes to see if one would be suitable.

    Good luck,

    Alex.

    in reply to: Earth to briefly gain second ‘moon’, scientists say #625396
    Alex Pratt
    Participant

    2024 PT5 was mag 17 when discovered in southern skies and is currently mag 22 at high northerly declination, but next January it will reach mag 18, within reach of more amateur imagers (if the MPC and NASA Horizons ephemerides fully include the perturbations from its flyby).

    Alex.

    • This reply was modified 3 months, 2 weeks ago by Alex Pratt.
    in reply to: Congratulations to Dr Andrew Wilson #625371
    Alex Pratt
    Participant

    I’ll pass on a piece of sage advice from my old supervisor – don’t use Dr. on a flight ticket!

    In my case I used it on a hotel booking in Scotland and had a waiter (at dinner) asking my opinion of his back problems. I advised him to see his GP!

    When on holiday a GP I know tells people they’re a vet.

    Alex.

    in reply to: Congratulations to Dr Andrew Wilson #625358
    Alex Pratt
    Participant

    Many congratulations Doc. Wilson!
    You can now expect to be asked by visiting tradespersons (as I once was) for assistance with treating assorted ailments!!
    Alan

    Alan, Andy,

    Our late friend Dr Dave Gavine – who was awarded Scotland’s first Open University PhD for his thesis ‘Astronomy in Scotland 1745–1900’ – related the story of a visit to the National Gallery of Scotland during which his mobile phone started ringing. As a member of staff walked over to reprimand him, Dave commented “Apologies, I’m a doctor…” 🙂

    Have fun with your title.

    Alex.

Viewing 20 posts - 1 through 20 (of 311 total)