Re: Satellite transits of Sun/Moon
Bruno Tilgner (Bruno_Tilgner@compuserve.com)
Mon, 20 Sep 1999 16:07:11 -0400
First of all my apologies for having sent my reply to Rainer
Kresken's question in German. I noticed the mistake a tad
too late, pressed the CANCEL button, but apparently it had
already gone.
Secondly, congratulations to Allen Thomson for nevertheless
having understood it very well indeed!
As to the questions:
>Could you tell us where that can be ordered?
The topographic maps (1:200 000 and 1:50 000) can be ordered in
any bookshop and also from the geographic survey offices. But
I doubt that they are of any use for someone not living in
Germany (which is the case for myself, but I go there from
time to time). More details on request (I suggest by private
mail).
>A more general question: Is there any mapping product like
>Delorme's Street Atlas available for Europe?
I don't know Delorme's Street Atlas, but I am very certain
that it does not exist for Europe. The closest thing I have
come across, again for Germany, is a street atlas for a large
number a cities, overlaid on aerial photographs which one can
zoom in and out upon at the same time as the street atlas.
It is indeed possible to identify individual houses. But I
have not seen it for any other country.
>But the fact that the sun is bright should make it possible to use the
>short-exposure technique to defeat the turbulence and produce
>near-diffraction limited silhouette images. You'd need a camera capable of
>taking a series of ~10 ms frames during the transit, plus a certain amount
>of luck in getting the turbulence to flatten out momentarily in front of
>your telescope. I wouldn't be surprised if Ron Dantowitz has tried this --
>it's a variant of the technique he uses to get high-resolution satellite
>images.
So far I have observed only visually at about 15x magnification. I now
have video equipment with which I could get 25 pictures per second (that
is the PAL standard used in Europe as opposed to the 30 pictures per
second for NTSC), but I haven't tried it yet.
Bruno Tilgner
Saint-Cloud, France