Optical 20 April 2009

From: Greg Roberts (grr@telkomsa.net)
Date: Tue Apr 21 2009 - 09:33:58 UTC

  • Next message: Russell Eberst: "2009APR21.OBS"

    Observations 20 April 2009
    ----------------------------
    
    Cosatrak 1 (Computerised satellite Tracking System).
    Camera mount now carries two systems that can be operated
    together as two totally different sytems and computers used.
    Generally the DSI Pro II camera will be used for high altitude
    slow moving objects. Tests seem to indicate that its sensitivity
    is comparable to the MINTRON ( possibly better) but as its not
    possible (?) to time stamp to better than 1 second accuracy the
    time resolution is not good enough for LEO objects.
    
    (1) 145mm focal length f/2.5 lens fitted to MINTRON low light
    level CCD surveillance camera (0.005 lux typical in non integration
    mode) and 0.00005 lux in STARLIGHT mode with 128 frame integration.
    Image integrated for 2.56 seconds but exposure depends on sky background
    brightness. Field of view 2.5 x 1.9 degrees and showing about mag +12
    stars in "real time". Used as a finder for the 6 inch reflector.
    Individual frames are video time stamped with GPS derived signal.
    
    (2)Meade DSI Pro II Monochrome CCD camera without filters.
    using integration times of 5 sec min to 25 seconds maximum
    depending on brightness of sky in particular area.No image
    processing done, but some done automatically in the auto reduction
    software.
    
    Used with 4 inch SKYWATCHER refractor- model 1025 - fitted with home
    made focal reducur to give an f/2.56 system. Image scale is 6.56 arc
    sec/pixel and field of view 84.8 x 63.2 arc minutes. Shows 15th
    magnitude stars in real time with reasonably good conditions.
    HOWEVER I forgot to remove the aperture mask that I had placed over the
    4 inch objective a few days earlier so that I could test the system out in
    daylight, so I was effectively using a 1.5 inch aperture telescope operating
    at about f/6.5 - no wonder my exposures were longer than normal!
    
    Exposure time to nearest second inserted into image FITS header
    from PC clock which is automatically checked every minute against
    GPS signal.
    
    Site 0433 : Longitude 18.51294 deg East, Latitude -33.94058 deg,
    Elevation 10 metres-situated in Pinelands (Cape Town),South Africa
    
    For CLASSIFIED.TLE
    ----------------------------
    14675 84 009A   0433 T 20090420193243500 16 35 0821691+110144 29  +133 25
    14675 84 009A   0433 T 20090420193602500 16 15 0824234+105652 58  +138 05
    14675 84 009A   0433 T 20090420193826500 16 35 0826345+108964 58  +079 21
    19976 89 035A   0433 T 20090420194959000 16 25 1152238+074112 19  +148 27
    19976 89 035A   0433 T 20090420195426000 16 15 1157205+073331 48
    19976 89 035A   0433 T 20090420195602000 16 15 1159092+073035 28
    23855 96 026A   0433 T 20090420204531000 16 15 1129363+090711 89  +142 71
    23855 96 026A   0433 T 20090420204813000 16 15 1132361+090050 89
    23855 96 026A   0433 T 20090420205345000 16 15 1138453+084803 89
    25336 98 029A   0433 T 20090420202120000 16 15 1325594+041606 19
    25336 98 029A   0433 T 20090420202346000 16 15 1328263+041053 19  +153 15
    27168 02 001A   0433 T 20090420194959000 16 35 1152023+076004 58  +145 59
    27168 02 001A   0433 T 20090420195426000 16 15 1156296+073340 68  +132 05
    27168 02 001A   0433 T 20090420195602000 16 15 1158058+073250 48
    32287 07 054A   0433 T 20090420202738000 16 35 1321471+027380 19  +143 20
    32287 07 054A   0433 T 20090420203436000 16 25 1328475+024647 39  +131 32
    33490 09 001A   0433 T 20090420200243000 16 15 1319462+032943 49  +080 05
    33490 09 001A   0433 T 20090420201046000 16 15 1327528+032319     +080 05
    33490 09 001A   0433 T 20090420201423000 16 15 1331308+032108     +080 05
    90022 04 764A   0433 T 20090420214018000 16 15 1232432+163334 28  +145 05
    90022 04 764A   0433 T 20090420214244000 16 15 1234590+162652 28  +151
    90022 04 764A   0433 T 20090420214515000 16 35 1237356+163381 59
    
    Strays seen:
    --------------
    THURAYA 2 geostationary
    27825 03 026A   0433 E 20090420202120000 16 15 1326551+032914 48  +080 05
    27825 03 026A   0433 E 20090420202346000 16 25 1329363+032773 98  +080
    
    
    Notes:
    -------
    
    (1) Terrible observing conditions - very thick cirrus mixed with
        cloud so had to use long exposures. Apart from #33490 all were
        measured automatically using the program APEX-II and took 9 minutes.
        A fair number of images were rejected due to the cloud messing up
        star trails. The magnitudes are totally useless due to the drifting
        cirrus/cloud.
    
    (2) Looks like my winter has started - almost continual cloud for the
        past few days made me desperate to observe as I wanted to check out
        the new telescope, the attachment of the focal reducer and camera as
        well as remote focussing, and a program I wrote to reduce some of
        the work required to process images before they could be processed
        in APEX-II
    
    Cheers
    Greg
    
    
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