Martin Lewis

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Viewing 20 posts - 1 through 20 (of 26 total)
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  • in reply to: Flaring of synchronous satellites from Kelling Heath #584876
    Martin Lewis
    Participant

    Interesting analysis Nick. What website is that data from?

    Thanks
    Martin

    in reply to: Flaring of synchronous satellites from Kelling Heath #584873
    Martin Lewis
    Participant

    To make this clearer I have cropped and rotated the video from the Sunday night (10th Oct) and boosted the brightness. Multiple flares occur across the mid line of the video as the anti-solar point moves across the southern sky from L to R. This runs from 22.18UT to 1-13UT. You can see the video here: https://vimeo.com/640645977

    Martin

    in reply to: Flaring of synchronous satellites from Kelling Heath #584846
    Martin Lewis
    Participant

    Thanks Grant,
    These are  much brighter than 5th magnitude though. Some were definitely 2nd magnitude.

    I guess they would be in the Earth’s shadow at the anti-solar point that’s maybe why they are brighter 45 mins before or after.

    Martin

    in reply to: Why do we still show the images upside down? #584688
    Martin Lewis
    Participant

    Hi Peter,
    It’s good to have a convention to make images easier to compare images and can’t see a reason not to stick with the existing arbitary one rather than change it after several centuries. Jupiter with a GRS at the bottom and a Mars with Syrtis Major at the bottom – to me they just don’t look right.

    It is arbitary whether it has been chosen to be north up or south up but south up is the existing astronomical convention. In the northern hemisphere that’s the view in an inverting telescope but from the southern hemisphere that is the view in an non-inverting set up. There is no such thing as the right way up or wrong way up just the conventional way up and the unconventional way up.

    I am intruiged by your comment that you see visually a view with North at the top when you view through an SCT with no diagonal. Surely an SCT with two mirrors should give an inverted view. I though it was only through a diagonal that  you would get a non-inverted view but it would be mirrored L-R.

    Cheers, Martin

    in reply to: mount vibrations #584232
    Martin Lewis
    Participant

    Sorbothane is good stuff in the right application but here won’t it make the mount very sloppy? 

    There is a great application guide for Sorbothane here: https://www.sorbothane.com/Data/Sites/31/pdfs/product-guides/Sorbothane-EDG.pdf and an even more useful design calculator here: https://www.sorbothane.com/Data/Sites/31/edg/vibration-calculator.html  Generally what is important is to compress the Sorbothane by 15-25% for best performance – so you pick your area to give you that compression for your given load.

    Martin

    in reply to: Update on my hunt for Micrometorites #583760
    Martin Lewis
    Participant

    What an interesting project Tracy. Very keen to hear how you get on. Might be able to do some EDX elemental analysis along with our next sample run in a few weeks if you can wait that long. Not sure on interpretation though.  EDX will tell you what elements are there in the first few microns of the skin.

    Martin

    in reply to: Update to member pages #583549
    Martin Lewis
    Participant

    Wanted to add a comment to POTW but after pressing submit. It said ‘blank comment ignored’ and nothing is showing.

    Martin

    in reply to: Update to member pages #583526
    Martin Lewis
    Participant

    I commented on that same image by Martina and liked it too but that info has gone too. As Paul says might be indicative of other missing info. Great job otherwise Dominic.

    But will animated Giffs work now??

    Martin

    in reply to: Update to member pages #583525
    Martin Lewis
    Participant

    I commented on that same image by Martina and liked it too but that info has gone too. As Paul says might be indicative of other missing info. Great job otherwise Dominic.

    But will animated Giffs work now??

    Martin

    in reply to: Mars dust storm alert #583388
    Martin Lewis
    Participant

    Image taken at 20.22UT last night in difficult conditions with Jetstream troublesome, shows Solis Lacus at the limb with significant dust above it.  See; https://britastro.org/node/25060
    Cheers
    Martin

    in reply to: Metal back distance #583267
    Martin Lewis
    Participant

    Hi,

    Why don’t you determine it empirically — as presumably it is the position where aberrations are minimised?

    Star test either side of a know positions further and further out from location of max in-travel. Use a digital video camera to capture the out-of-focus start images and allow you to average them and you’ll have a record of the intra and extra focal images for each mid-location. Best position is where the intra and extra focal images are most similar to each other.

    Cheers
    Martin

    in reply to: Fullerscopes Finchley Road #582717
    Martin Lewis
    Participant

    Yes, sage advice David – alarm bells were ringing in my ears as I read it. Didn’t want to end up in the small claim court myself!

    Martin

    in reply to: Fullerscopes Finchley Road #582712
    Martin Lewis
    Participant

    Thanks Daryl,

    I remember reading that saga before in your first link.

    I did find the picture in the bottom link which is very good but really wanted the later frontage with the round window I used to stare through!

    Thanks for your help anyway,

    Best wishes

    Martin

    in reply to: Raspberry Pi Camera #582404
    Martin Lewis
    Participant

    That chip size is plenty big enough for a decent all-sky camera and plenty of 180deg fish eye lenses to suit such as the Arecont f2 1.55mm lens. You can see all-sky pictures taken with that lens and a chip just 4.8mm x 3.6mm here; http://skyinspector.co.uk/allsky-camera-ii

    Cheers
    Martin

    in reply to: Advanced Planetary Imaging Workshop #582039
    Martin Lewis
    Participant

    Updated details of the ‘BAA/SPA Advanced Planetary Imaging Workshop’ and the full agenda for the day have recently been posted.

    We are please to announce that the following speakers have confirmed; 

    • David Arditti (planetary imager and BAA Equipment and Techniques section director)
    • Pete Edwards (planetary imager)
    • Chris Garry (planetary imager and author of PIPP)
    • Chris Hooker (planetary imager and BAA Mercury section coordinator)
    • Simon Kidd (planetary imager)
    • Emil Kraaikamp (planetary imager and author of Autostakkert)
    • Martin Lewis (planetary imager and BAA Equipment and Techniques section advisor)
    • Damian Peach (imager and BAA Jupiter section assistant director)

    It promises to be a most interesting and popular event so don’t miss out on the limited places available. Reductions for BAA and SPA members.

    Details given at; https://britastro.org/node/19008

    See you there,

    Martin Lewis & David Arditti- event coordinators

    in reply to: Image Posting on Members Pages #581388
    Martin Lewis
    Participant

    Thanks Andy,
    Wonder why it never suggests anything for those field but always for the fields above then?
    Thanks for the understanding anyway.
    Best wishes
    Martin

    in reply to: Members Pages Enlarged Images #581110
    Martin Lewis
    Participant

    Thanks Andy,
    That is a very comprehensive reply and very helpful.
    Thanks for your testing,

    Martin

    in reply to: Members Pages Enlarged Images #581095
    Martin Lewis
    Participant

    That’s interesting. I wonder why some enlarge further when click and for others nothing happens? Curious. Some of mine are uploaded as jpegs and some as pngs- will see if it relates to that.

    Thanks for the suggestion anyway, Peter

    Martin

    in reply to: Members Pages Enlarged Images #581094
    Martin Lewis
    Participant

    Yes David,

    It would be great if it did that but generally the image is hardly any bigger. Why is that one different?

    Cheers,
    Martin

    in reply to: Planetary Histograms #580948
    Martin Lewis
    Participant

    Hi Ron,

    This is a step I often do to darken the background on planetary images including images of the Ice Giants and particularly images taken in daylight or bright twilight, often Mercury or Venus. I would always do this after wavelet processing as the application of the wavelets will change the histogram distribution quite markedly. You won’t lose planetary data unless it is something very dark like the Crepe ring on Saturn. Removal of the background like this is a simple way of boosting the contrast.

    Martin

Viewing 20 posts - 1 through 20 (of 26 total)