Dr Paul Leyland

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  • in reply to: Back issues of BAA Handbook. #585222
    Dr Paul Leyland
    Participant

    Thanks to the generosity of several members there are now very few gaps in my collection of BAA handbooks. I also have a few which can be provided to anyone interested.

    My missing volumes are now 1979, 1985, 2004, 2005, 2007 and everything before 1949.

    Available free to good homes are 1964-66, 1968-73, 1977 and 2010.

    VSS Circulars from the late 90s may become available if anyone is interested. They need sorting out before I can say yay or nay.

    in reply to: Back issues of BAA Handbook. #585175
    Dr Paul Leyland
    Participant

    Hi Michael,

    Now in the post.

    in reply to: Back issues of BAA Handbook. #585176
    Dr Paul Leyland
    Participant

    Thanks Roger!

    I’ll send you an email.

    in reply to: Members’ Pages – Bortle scale – suggestion #585131
    Dr Paul Leyland
    Participant

    It is a long time since I observed in Bortle 7 skies so I can’t really remember what the sky looked like. What I can say is that in La Palma to me the night sky is very definitely blue for 2 or 3 days either side of full moon and I can’t see anywhere near as many stars with the NE as I can two weeks earlier or later.

    Colour perception might be a personal response. I’ve unusually light-sensitive eyes as a consequence of a bad attack of measles when I was a small kid.

    in reply to: Members’ Pages – Bortle scale – suggestion #585128
    Dr Paul Leyland
    Participant

    Note that I. like many imagers, routinely image objects which are fainter than the sky. Long integration times and background removal software are much more feasible with a CCD than a retina!

    in reply to: Members’ Pages – Bortle scale – suggestion #585127
    Dr Paul Leyland
    Participant

    I don’t have a SQM either, but I still find the numerical value useful, and for essentially the same reason as you like the NLM.

    Both give an indication of when the brightness of a stellar object is comparable to the brightness of the sky when observed with a particular optical train and detector. My eyeball is 100 times (5 mags) less sensitive than my CCD and has a resolution 30 times poorer (circa 1arcmin compared with 2 arcsecond seeing limit), so one resolution element of my eye collects 900 times as many photons as in one of the CCD, another 7.4 magnitudes.

    Plugging in the numbers, a NLM of 6.3 corresponds to 6.3+5+7.4 =18.7 sky limit for my scope.
    The corresponding instrumental estimate is 21.2 – 2.5 * log (2 * 2* π) magnitudes for the sky, which evaluates to 18.5.
    That is a remarkably satisfactory agreement!

    in reply to: Members’ Pages – Bortle scale – suggestion #585124
    Dr Paul Leyland
    Participant

    I support this request and would add another, closely related one.

    The Bortle scale, as well as being a simple number, is also a measure of sky brightness in terms of equivalent stellar magnitude per square arcsecond. I can never remember that Bortle 4 is, for example, 20.49–21.69 and invariably have to look it up at https://en.wikipedia.org/wiki/Bortle_scale

    If the Bortle scale is added, could it be something along the lines of “Bortle 4 = 20.49-21.69 mag/(sq-as)”?

    Thanks,

    Paul

    in reply to: Suggestions for CV stars in the Southern Hemisphere #585084
    Dr Paul Leyland
    Participant

    What a shame.

    KK Tel at a declination of -52.3 degrees rises above my physical horizon (or so I believe, as I’m not sure what the physical horizon is any more) but is too far south for the design of the mount which limits me to a declination of -47.5 degrees. V877 Ara at -65.5 is much too far south.

    PU CMa is no problem. I already monitor HL CMa.

    Even if KK Tel was accessible it would be so low that precision photometry would be exceedingly difficult. The best I could do is pick up and announce an outburst.

    Oh well. If you find any others north of -47, please let me know by posting here.

    in reply to: Following JWST through Orion to L2 #585079
    Dr Paul Leyland
    Participant

    I asked Jonathan McDowell about the value of tracking the Ariane for as long as possible.

    He responded that it would be very useful to get as good an orbit as possible so that it can more easily be recovered when it returns to this neck of the woods in 2047.

    The astrometry is being co-ordinated by Bill Gray at http://projectpluto.com and I urge anyone here, especially the asteroids people, to follow it as long as possible.

    in reply to: 2021 – how was it for you? #585073
    Dr Paul Leyland
    Participant

    Not every year I get a ring-side view of a volcanic eruption.

    in reply to: Following JWST through Orion to L2 #585044
    Dr Paul Leyland
    Participant

    3 minutes early…

    in reply to: Daylight photometry #585040
    Dr Paul Leyland
    Participant

    Undoubtedly worth a try but you may have difficulties finding the target without a well-calibrated mount and having suitable comparisons in the FOV might also be hard. It goes without saying that the sky brightness will be so perhaps observing in the  red and  near-IR (r’, i’, z’, Rc, Ic, etc) might be advisable.

    One of my images of a Venus – Neptune conjunction shows a 12th mag field star in a 2 second exposure in i’ — though not bright enough to be measurable, taken just 37 minutes after sunset. Essentially everything on the binocular program should be accessible.

    Thanks for a good suggestion, I may try it when back in La Palma.

    in reply to: Following JWST through Orion to L2 #585035
    Dr Paul Leyland
    Participant

    Just Wait, Still Terrestrial.

    in reply to: Following JWST through Orion to L2 #585026
    Dr Paul Leyland
    Participant

    I will see what I can do, but as Tacande Observatory won’t be back in operation until February at the very earliest it will likely take relatively long duration imaging. Gaia is still within range of my kit (must try for it one day) so JWST shouldn’t be too much of a problem.

    Thanks for suggesting this target!

    in reply to: Awards citations #585024
    Dr Paul Leyland
    Participant

    “Maximum on A4” when printed in 3-pt FlySpeck font?

    While I agree with your general sentiments, I believe any limit should be a little more precise. Perhaps 1000 words or something like that?

    That said, both storage and bandwidth are essentially free these days. A picture is worth a thousand words — well, costs more anyway — and the BAA is quite happy to host many thousands of images. No technical reason to be parsimonious; the judgement should be based purely on aesthetic issues. My opinion, anyway.

    in reply to: IAU Pro-Am Collaboration Survey #585019
    Dr Paul Leyland
    Participant

    My bit added to the pot.

    I have also publicised this survey on the social media fora I frequent. Others might wish to do likewise.

    in reply to: Person of the year #585012
    Dr Paul Leyland
    Participant

    Thank you, you are quite correct. Mea culpa.

    in reply to: J-BAA Electronic #584977
    Dr Paul Leyland
    Participant

    I have the electronic subscription for two main reasons:

    a) I am a cheapskate and it’s cheaper;

    b) I already have far too many chewed trees in each of two houses. Doesn’t stop me collecting more, unfortunately …

    I read both JBAA (and similar publications) formats about equally often and likewise in depth.  There is something immensely comfortable about having a physical artefact, especially one which is much safer to read when lying in a hot bath or a sauna. That said, the portability and physical storage space of a digital version has a lot going for it.

    Horses for courses.

    in reply to: Guidance on used prices #584976
    Dr Paul Leyland
    Participant

    I would love to have the C11, so I am in that minority.

    Unfortunately I can not justify buying one but I can ask around.

    in reply to: Guidance on used prices #584975
    Dr Paul Leyland
    Participant

    For what it’s worth, I have heard from a couple of sources that if you want to buy a Meade OTA it can be cheaper to buy one fork-mounted and then throw away the mount than it is to buy one not so encumbered. That is a pretty damning assessment of the quality of a Meade fork mount as it implies its value is negative!

    Takeaway message: if your kit is fork mounted, try advertising the OTA and offer to throw in the mount at a small increment in price.

    As always, YMMV.

Viewing 20 posts - 361 through 380 (of 778 total)