Re: Stopwatch advice

From: Mike McCants (
Date: Sun Oct 29 2006 - 12:56:42 EST

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    Bjorn posted:
    >How accurate are your own clicks?
    That depends on a lot of variables.  :-)
    But the 0.01 second value is usually pretty random unless
    it's a very well-defined flashing object.
    Last night Ed spotted the new Long March rocket object 29507 (06 46C).
    It was flashing to about magnitude 5.5 every 1/2 second.
    My stopwatch values (start time was 0:40 UT Oct 29):
    49:50.15 difference 5.31
    49:55.53 5.38
    50:00.96 5.43
    50:06.26 5.30
    50:11.63 5.37
    50:16.98 5.35
    Each click was a count of 10 flashes.  So the total time for
    60 flashes was 32.14 seconds and the flash period was 0.536 seconds.
    So in this case, the hundredths of a second are marginally useful.
    But when ItalSat 1 (21055, 91 03A) flashes every 59.7 seconds
    (maximum about 01:46 UT Oct 29), the hundredths are pretty random.
    Of course the stopwatch beeps when the spilt button is pressed,
    so there are cases when I realize that I was off 1 or 2 tenths of
    a second and I can write that fact down when I record the time.
    For a lot of the objects I track at 3000, 10000, and 23000 miles,
    even the tenths of a second value is not very important.
    For the usual NOSS or DMSP objects at a range of 400 to 800 miles,
    1/10 of a second represents about 0.4 mile and that's about 0.04 degrees
    or so on the sky.  My personal problem is that I have two telescopes
    with rather small fields of view (2 degrees and 0.8 degrees) mounted
    on a Dobsonian mount that does not turn easily (you get what you
    pay for).  So I often have trouble planning ahead for whether or
    not the object will go near a star that I believe that I can later
    I have found that each observer of classified objects is likely to
    have his own "personal equation" that will make his observations
    slightly different from the "group average".  Typically my observations
    are about 1 or 2 tenths of a second "early" compared to the "group
    average".  So my opinion is that plus or minus 2 or 3 tenths of a second
    is good enough to make a worthwhile contribution to the tracking
    effort.  (Of course for "high drag" or "difficult to observe" objects,
    an observation plus or minus 5 seconds may be very useful.)
    >The two features I need most are a 'Recall' mode that does not start from
    >lap 1 each time - I have one like that. And a 'Stop' button that will not be
    >hit accidentally.
    The "recall" button does 3 stramge things and the 4th push gets
    you back to the last split.  Then each split after that is one
    previous split.  I. e., ignore, ignore, ignore, same (23 say), then
    22, 21, 20, etc.
    At all times (even during recall) the top display shows the difference
    between the displayed split time and the previous split time.  The
    bottom display shows the current (continuously changing) elapsed time.
    The split and stop buttons are on the top of the stopwatch.
    The recall button is one of the 4 buttons on the face of the stopwatch.
    I hold the stopwatch in my left hand and push the split button
    with my thumb.  After 15 years, I almost never make a mistake.  :-)
    >Next on the wishlist is USB connection for downloading all
    >elapsed times.
    Although a certain person I know usually takes his watch home and
    records the times, I always write down the splits immediately.
    Often I need to write down whether the object passed north or
    south of the star and by how much or how bright the flash was.
    Sometimes I look at the intermediate splits on a tumbling object
    and simply write down the first and last split and the number of
    cycles that took place between those splits.
    Other interesting observations from last night:
    About 2:40 (Oct 29 UT) last night, Ed spotted a flashing object
    moving very slowly from south to north.  I have identified it
    as Cosmos 1414 (13606, 82-100D) - a Glonass.  It flashed up to
    about magnitude 5 or 5.5 every 12.4 seconds for about 10 minutes.
    The newly launched Stereo Delta rocket (29512) was observed
    varying slowly from magnitude 5 to 5.5.
    The NOSS 7 (A) object (16591) was observed to flare to about
    magnitude 6 at a range of 1000 miles at alt 55, azi 240.
    This is about 3 magnitudes brighter than usual.
    A 20 minute search for TiPS picked up 4 strays.
    Ed had predictions for 3 known flashing near-geosyncs in the
    same part of the sky and he spotted flashes from Yuri 3A (20771, 90 77A)
    about 04:30 UT.  It flashed every 91.7 seconds, but some flashes
    were very bright and some were very faint.  It also tumbled to magnitude
    10 or 11 at other times.  Ed thought he saw flashes from Gstar 3
    (19483, 88 81A) just about Yuri 3A every once in a while.
    While we were tracking Yuri 3A in the 8 inch, Ed noticed that
    GStar 1 (15677, 85 35A) was tumbling in the same field.  It
    tumbled to about magnitude 10 every 61 seconds.
    Friday night:  Milstar 1 (90023) continues to drift to the east.
    It is now altitude 22 degrees in my east.  It's going to go out
    of my visibility fairly soon.  It was flaring to magnitude 7.5
    about 3:30 UT Oct 28.  
    The Solar B rocket was (again) observed varying from magnitude 4 to 7
    in the west.
    The comet has been quite spectacular. can only be obtained from my web page.
    Mike McCants
    Site BCRC - 30.3N 97.8W
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