Re: Iridium : observing project , Iridial constellation

From: Walter Nissen (wnissen@tfn.net)
Date: Wed Jun 15 2005 - 20:01:59 EDT

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    Hi, Steve,
    
    Thanks for your response.
    
    > I have a picture of these 2 Iridiums flaring on 5/4/05 at 10.12 PM
    > local time EDT.  It was my first picture of an Iridium flare. ...
    > It can be seen at http://www.geocities.com/satman888/Nightsky.html
    
    Very nice!
    
    I keep telling Marylanders that Ohio is just a suburb of Maryland;
    and our simultaneous observations of these events prove it.
    My ancient version of IRIDFLAR shows the glints much brighter at
    Newcomb, MD, than at Nissen, OH.
    Your image shows a glint from Iridium P3 B below right of a brighter
    glint from Iridium P35.
    Ir P3 B was about 5s ahead of Ir P35.
    Your image captures the glinty appearance of mirrors very well.
    The pulsed appearance when the image is rendered small is an artifact.
    The image shows M13 with its two attendant 8th-mag stars, and also
    NGC 6058 (which the RNCG gives as mag 13.5) just barely detectable
    (or maybe this is a brighter nearby star).
    Some of the bright stars shown are:
    44 eta     Herc
    35 sigma   Herc
    12 lambda  CrB
    11 kappa   CrB
    18 upsilon CrB
    14 iota    CrB
    
    I think even my ancient version of IRIDFLAR uses 2000.0 coordinates, and
    I measure the center of the glint from Ir P3 B at roughly
    alpha = 15h 56m, delta = +32.9 degrees
    and the glint from Ir P35 at roughly
    alpha = 15h 59m, delta = +35.6 degrees.
    The predicted time from IRIDFLAR seems to have been much more accurate
    for Ir P35, a member of the operational array, than for Ir P3 B, a
    presumed spare, presumed to be under less precise control, and which
    seems to have glinted perhaps 8s later than indicated by IRIDFLAR.
    I think the trails end because you stopped recording; QuickSat indicates
    the objects didn't go into shadow until beyond the edges of your image.
    With the elsets for these objects just before and just after the events,
    it would probably be possible to make a quite accurate estimate of when
    you stopped recording.
    
    Cheers.
    
    Walter Nissen                   wnissen@tfn.net
    -81.8637, 41.3735, 256m elevation
    
    P.S.  For the timings in my last message for Ir P38, I incorrectly
    reported that the stopwatch was 4.43 sec slow, when it was, in fact,
    about 4.43 sec fast (from 2 hours slow).
    The estimated times were correctly reported from my log.
    
    ---
    
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    ---
    
    Latitude:  39.47070  Longitude:  -79.33880  Altitude:  839.0 m
    Time Zone: UTC  +0.0 h
    
                          Iridium Coordinates  Range   Sat   Solar               
    Peak  Std    Maximum Flare
    Ir   Date      Time    Azm El   RA   Decl  (km)  N Ill Azm  Elev M FlrAng Mag 
    Mag  Mag Latitude Longitude
    
    51  5- 5- 5  2:11:56.0 074 40 16h03  35.1 1095.7 D Lit 313 -19.4 R  1.62  0.6
    -7.9  0.3  39.5205  -78.8207
    35  5- 5- 5  2:12:01.5 073 41 16h00  36.0 1117.0 D Lit 313 -19.4 R  0.51 -2.8
    -7.9 -3.1  39.4885  -79.1788
    
    ---
    
    (extract from my ancient version of QuickSat):
      39.471  79.339 2753.    Newcomb, MD <-------- 2000 17.5  4 F F T F F
    
    ***  2005 May   5  *** Times are UT ***   1 5  920
    
     H  M  S  TIM AL AZI C   U  MAG   REVS  HGT SHD  RNG  EW PHS  R A   DEC
    25262 Iridium 51 +3                    1.0   T
     2 11 56   .0 40  73   138  1.7   13.2  755 175 1099 1.0  54 16 3  35.4
     2 12  1   .0 40  76   139  1.7   13.2  755 161 1095 1.0  52 1558  33.7
    24968 Iridium 37
     2 11 56   .0 41  70   138 20.8   13.2  784 221 1125 1.0  57 16 5  37.9
     2 12  1   .0 41  72   138 20.8   13.2  784 209 1120 1.0  55 16 0  36.5
    
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