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Why is the Exact Time important?
There are 1440 (24 x 60) minutes in a day while the Earth rotates 360°.
That means the Earth rotates 0.25 degree/minute. The field of view of
a 26 mm eyepiece on ETX-90EC is 1.1 degrees. If the telescope is not tracking
the target object, it will go out of view in 4.4 (1.1/0.25) minutes.
Every one minute
of error in the Autostar's time, the target object will be off by
seconds or 0.25°. If the time is off by 4 minutes, the target object
will be off by 1°. Needless to say, if you do not set the Autostar's
time to the exact time, the telescope will not point to the exact
location of your target object either. Remember, a half of a degree off
here, a quarter of a degree off there, and you will miss the target.
Your Polar alignment and Alt/Az alignment with affected.
Your
DC3-updated PC System Time
DC3
is a freeware utility program that will synchronize your PC system time
an atomic clock server to hundredth of a second. See Precision Time
Source.
Radio Digital
Atomic clock
NIST (National Institute of Standards and Technology) radio station WWVB
continuously broadcasts time and frequency information on its 60 kHz
carrier frequency from Fort Collins, Colorado. WWVB provides coverage to
the United States, Mexico, and Canada. The WWVB time code provides a
convenient reference for many consumer electronic products such as desk
clocks, wall clocks, and wristwatches.
Radio digital
atomic clock receives a special radio signal up to four times per day to
ensure accurate time within a nanosecond. Radio digital atomic clocks
are not expensive, priced at about $40.00. Some of the radio digital
atomic clocks even come with a thermometer. These atomic clocks are
about the size of a pack of cigarettes.
Synchronizing
Your Digital Watch with Computer Time
Your computer should now be updated with DC3. You may want to
synchronize you digital watch with the computer time. Since different
digital watches work differently, I will just use my Casio digital watch
as an example. In my case, I bring up the PC clock and set my digital
watch to about 30 seconds ahead of the PC time. My watch allows me to
set the seconds to "00". Let's say the PC time is 6:32:30, I
would set my digital watch to 6:33:00, when PC time reaches 6:33:00, I
release the button on my digital watch. My digital watch is now
synchronized with the very accurate PC time. I therefore always set my
watch before I start my star gazing session if I'm not using my
computer.
Different digital
watches work differently; please refer to your digital watch's manual.
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