Re: 300 mm work

From: Greg Roberts (
Date: Sat Jun 06 2009 - 07:37:43 UTC

  • Next message: Ted Molczan: "TJM obs of 2009 Jun 06 UTC"

    Morning Gerhard
    Had a look at your 300mm image and not much one could do with that--so you need 
    a better mount.Its easy enough to construct an altazimuth mount using standard 
    pipe fittings. In my early days of tracking I made such a mount and it worked 
    quite well. Maybe today one doesnt use mild steel pipe fittings and its all 
    plastic but one should be able to get the necessary mild steel fittings . What 
    you need is a mild steel pipe about 5-6 feet long, around diamater 2.5 to 3 
    inches and put the one end in concrete making sure the pipe is truly vertical 
    using a spirit level. Before putting the pipe in the ground have the one end 
    threaded so that it can take a matching "T piece". Also mount a plastic 360 
    degree plastic protractor just where the thread ends - one could get two sizes - 
    one about 3-4 inch diamater and the other about 6 inches and graduated in 1/2 
    degree intervals from the CNA ( Central News Agency). This will form your 
    azimuth bearing. Then get a short threaded ( about 2 inches or so) length of 
    pipe - I think they are called "nipples" in the industry - one end screws into 
    the one part of the T piece and on the other end you mount a pipe flange. This 
    will form your "altitude" axis. At the same timet mount another 360 degree 
    protractor on this end of the T piece and this will form your altitude circle.
    Your "bearings" are actually the threaded bits of pipe- not ideal as normally 
    these threads ( about 8 per inch) have a slight taper on them - ideally if you 
    know someone locally with a lathe you could ask them to cut the threads. You can 
    mount your camera/whatever on the pipe flange and then you should have a nice 
    steady cheap mount that you can aim in azimuth and altitude. If my instructions 
    arnt that clear I could make a drawing and send that to you.
    I suggest you work in azimuth and altitude. Working in RA/Dec with your set-up 
    is more difficult and unless you have a sort of permanent mount setup you would 
    have to setup every time you observe. Whilst we report our positions in RA/Dec I 
    think most observers work in az/el if using a mount of any sort (unless they 
    have a permanently mounted equatorial mount)- certainly az/el is more convenient 
    for slow moving stuff and especially geostationaries . Binocular observers will 
    probably prefer RA/Dec but this requires preparing for observing with little 
    charts etc so as to find the location or working in "real time" with star charts 
    etc. In tracking satellites one wants to be able to easily jump from one 
    position to the next - dont ask me how Russell and David for example observe so 
    many satellites in such a short time - used to take me many minutes to find a 
    star field and even longer to get a position!
    Scott has/had a nice picture on his website of one of his earlier setups where 
    he had a homemade mounting for his video camera - made out of wood - sort of 
    dobsonian type mount - this would be ideal for your situation as it would be 
    easy to add "setting circles" etc . I could probably find the picture of it 
    somewhere in my thousands of files if no longer on Scotts webpage.
    Hope this helps
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