Re: meade etx 70 and canon 20 d

From: Scott Campbell (campbel7@stelera.net)
Date: Sat May 16 2009 - 16:45:40 UTC

  • Next message: David Brierley: "DMB Obs May 15-16"

    GERHARD GROENEWALD wrote:
    > ULTIMATE AIM.
    > Setup Canon 20 d on equitorial mount at heavensat predicted ra and dec. 
    > take image with slew mount, over say 30 secs. No star trail, and clear 
    > satellite trail.
    > is this feasable ?
    
    Hi Gerhard,
    
    There isn't a "standard" way to image satellites.  As far as I know each 
    observer is imaging with unique equipment and methods.
    
    I use two different sets of gear, one for GEO's and high altitude 
    satellites and a different setup for LEO's which are fast and generally 
    brighter.  For faint and slow satellites you will want to either track 
    the satellite (satellite tracker software or CoSaTrack) or just keep the 
    camera still (tracking OFF) to track at a geostationary rate.  This will 
    allow light to accumulate on your imaging chip and bring in the faint 
    sattellites.
    
    For low and fast satellites you can position the camera ahead of the 
    satellite and expose the image as the satellite passes through. A one 
    second exposure or less is probably enough as the satellite will leave a 
    streak anyway.  Only the background stars will increase in brightness 
    with additional exposure time.  A sensitive video camera (MINTRON) and a 
    large lens with a large fov (telescope+focal reducer) are very desirable 
    for this type.
    
    If you are planning on making position reports accurate timing will be a 
    concern.  One of the advantages of imaging is that you can use a GPS 
    timestamp (KIWI) to record accurate time directly on a video image 
    (MINTRON again).  Another aadvantage to imaging is that you can replay 
    the pass and take your time locating the satellite among the backround 
    stars.  ObsReduce and Heavensat are great for this application.
    
    Here is a link to my equipment.
    
    http://www.coastalbend.edu/acdem/math/sats/setup.htm
    
    I currently favor the telescope and CCd camera.  Accurate time is 
    provided for through the timestamp on the image fits header.  This is 
    not as accurate as the GPS timestamp on video images but it is within 
    0.2 seconds....good enough for slow movers.  the position reporting is 
    now virtually automatic with the use of APEX II software.  Greg Roberts 
    and I have plowed through the installation and operation of APEX and can 
    probably help anyone who wants to use it get started.
    
    Good luck with your project.  Expect that it will change and expand as 
    you proceed.
    
    Scott Campbell
    Beeville, Texas
    Cospar 6226 28.4861N 97.8194W 107m
    http://www.coastalbend.edu/acdem/math/sats/
    campbel7@stelera.net
    
    
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