Setting Accurate Time
on the PC
(does anyone really know what time it is?)*
When using TheSky
astronomy software
with a robotic telescope mount setting accurate time is strongly recommended
and a must for TPoint mapping the telescope. Accurate time is extremely important for example when using a
telescope mount like the
Paramount ME which
does not rely on syncing from night to night but rather has its' own
internal clock and requires accurate time being supplied on startup. Setting accurate time
is also true for other "goto" mounts like the Meade LX-200 series, Celestron, AstroPhysics, Temma, Los Mandy, etc.). If you are planning on slewing to objects like
planets, minor planets, and or comets accurate time is also a must. And lastly accurate time
stamping is also extremely important when the CCD images will be used for
performing accurate astrometry!
Simply put the more accurate the time the better.
Time good to the second is easily obtainable and "good" enough. Note the Air Force is time stamping FITS images to 1 billionth
of a second (1 nanosecond) using CCDSoft with custom software that allows
timing the CCD camera's shutter to several military geosynchronous satellites.
If you are using the software to view where objects are
placed in the sky the time only needs to be good to a few seconds and
latitude and longitude good to 100 miles or so is sufficient.
Both PC clocks and those built
into most commercial "goto" telescopes are notorious for not keeping good
accurate time. Because there are so many options for setting accurate time now
(including the latest versions of Windows offering a time service), the
Internet, Atomic Clocks, dial-up services, GPS, etc. TheSky version 6 no longer provides a
method to set the PC clock, nor does it need to.
With telescopes like the
LX-200 once the PC clock is set accurately TheSky can in fact pass accurate
time and location settings by passing the data to the telescope. This is
much easier than trying to use the hand paddle to set lat/long, date/time,
and time zone and is less prone to user input error. See TheSky's
manual for details on how to pass the time and location settings into the
telescope.
A search on the Internet
yields dozens of sources for setting accurate PC time. If you have the
ability to access the Internet you can easily set the time of your PC on a
regular basis with an always on connection.
This can be done with a dial-up connection as well but may or may not be
accurate enough over several hours of time. With an always on connection you can actually have your PC
clock being updated in the background in frequent intervals like every 30
seconds, every 2
minutes, every 10 minutes, every hour and so on thus always ensuring
reasonably accurate time.
My personal favorite for
setting accurate PC time is a ShareWare program called Dimension 4 by
Thinking Man Software.
I have used this software for many years now and because it has never let me
down and it has every feature I want I have not tried anything else. It is small to download, free, and works
extremely well, and I have never had any issues with it. The options
it offers are very straight forward. I have yet to find a better
application (again free) for setting accurate PC time. See below.
Generally I have the program
start up on boot, run minimized, and set the time as frequently as every
couple of minutes. For a CCD imaging session you can change the
interval to something as frequent as every 30 seconds to 1 minute assuming
you are always connected to the Internet. That ensures very accurate time
stamping.
I have not had any experience with the use
of an atomic clock whereby you can insert a card in the PC or access the
external clock with a serial port but these will work as well. The advantage
there is they do not require an internet connection or modem dial-up.
Other Time Setting applications
***The band Chicago
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