Q. As an astronomer, why do I need a GPS based (with PPS) Time Server?
You may not. If you're a strictly visual observer, and have no interest in satellite tracking, you probably don't need one.
If you do any kind of scientific observing such as occultations, eclipsing binary timings, exoplanet transit timings, GRB timings, photometry, astrometry you definitely need an accurate times server.
If you're doing any kind of LEO (low earth orbit) satellite tracking, you definitely need a GPS based (with PPS) time server.
If you're an astrophotagrapher, then you also definitely need one. Most computer clocks are inherently inaccurate. If you're computer clock deviates by about 66 mSecs, your images will drift by about 1 arc second (if you're imaging near the celestial equator).
My laptop computer (Dell XPS) drifts by almost 900 mSeconds (about 13 arc seconds in sidereal position) per day.
Using our timeserver, I'm able to consistently image 5 minutes exposures, using no autoguider. Here's an example using our Alt/Alt mount with a de-rotator, a PlaneWave CDK 12.5", and an SBig ST11000. Keep in mind I didn't throw away any exposures. Our Time Server was adjusting the PC time every 15 seconds.
If you're already a SiTech user you can also send the site Latitude/Longitude/Elevation to SiTechExe.
Q. As a non-astronomer, why do I need a GPS Based (With PPS) Time Server?
Again, maybe you don't need one. But there are many other applications that require an accurate NTP time server: stock quotes and transactions, cryptocurrency mining, or maybe you just want your computer to have a very accurate time.
If you manage a network, you definitely need a time server. Ours is accurate to at lease 0.5 mSeconds, so, if that is accurate enough for your network, this is a wonderful and economical alternative to other more expensive units.
Q. I can just use an internet based time server, right?
Maybe, but in my experience, some internet time servers can be off by 20 or 30 seconds! I learned this the hard way, trying to track the ISS, with an internet time server. When I installed our SiTech Time Server, those position problems went away. If you find a high quality internet time server, then normally it can be within about 10 or 20 mSecs, but sometimes, out of the blue, it will come back with a time that's off by over 50 or 60 mSecs (about 1 arc second of motion at equator).
Why use the SiTech TimeServer?
1. It uses a high quality GPS chip, with a PPS signal and a high quality active antenna, which aligns the time server clock at the top of the second to the nearest (at worst case) 1/2 a millisecond.
2. You have the advantage over most GPS based NTP time servers of having additional features, Latitude, Longitude, Elevation, etc. available.
3. You can configure the time server with a USB port.
4. Our software allows you to set your PC clock with an interval you specify. We usually update my PC clock every 15 seconds while we're imaging.
5. Using our software, you can specify 2 time servers in the configuration, so you can compare time servers in the log file.
6. Using our software, you can simply log the NTP times from our time server (or other NTP time server) without actually setting your PC clock, to find out how much your PC clock is drifting, or you can set your PC clock.
7. Using our software, you can freely upgrade the time server firmware and software when available.
8. It is the most economical GPS (with PPS) based time server available (that we could find).
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