(meteorobs) Fwd: Determining Altitude & Azimuth From All Sky Cam Images (fwd)

[Larry]

If "close" will do..........

If (PRECISE) measures are not absolutely necessary, it is a simple task to 
match camera boresights with zenith when (in my case), Vega crossed zenith 
on Sept. 27, '09 e.g. This is best done with 3 or 4 turnbuckles attached to 
camera mounting column for steering the camera zenith.

Build an overlay circular Azimuth degree graph based on Zenith, North Star, 
and the fitting dimensions of software photographs.

Build a circular overlay graph which corresponds to Altitude.

Combine the overlays.

Check all of the above at periodic intervals with Planets, Stars, and 
ephemeris programs to determine degree of error and changes in the 
mountings.

But then I don't chase rocks...... :-)

YCSentinel




----- Original Message ----- 
From: "Ken Tapping" <Ken.Tapping at nrc-cnrc.gc.ca>
To: <meteorobs at meteorobs.org>
Cc: <jbrower at meteorchaser.net>
Sent: 2009/12/07 14:05
Subject: (meteorobs) Fwd: Determining Altitude & Azimuth From All Sky Cam 
Images (fwd)


> Hi,
>
>    We can discuss this further and will pass along a writeup.
>
> The camera image gives x,y pixel addresses that have some relationship
> with the sky. We need to know what pixels correspond with the camera
> boresight and with the zenith. We need also to know the relationship
> between radial distance from the camera boresight and angle from the
> boresight. From this we get the camera azimuth and the angle from
> boresight. We need also to know the relationship between camera azimuth
> and real azimuth.
>
> We make star images, using long or stacked exposures. Using an ephemeris
> program we get on the screen an image of the sky at the location and time
> of the camera exposure. The ephemeris program gives us the azimuth and
> elevation of stars at the time of the exposure. We then endeavour to
> locate those stars in the camera image, and get the camera azimuth and
> angle from boresight. Then we do a massive fitting exercise to establish
> the relationship between the camera coordinates and the outside world.
>
> A note discussing that is attached. As you might guess, this is something
> we are still working on. In the note we assume the camera is set up close
> to the zenith, so the distance  between the centre pixel and the zenith
> pixel is small.
>
> Regards,
>
> Ken
>
>
> -- 
> Dr Ken Tapping
>
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