[Aavso-photometry] Re: Atomic Clock Synchronization -

[Greg Crawford]

> Also, bear in mind that AboutTime attempts to calculate the ping time and make
> adjustments for it.

I have also recently discovered that another software application I use, MPO
Connections (including SBScripter), has a time sub-applet within it that polls
time on a regular basis; and also forces time synchronisation just before and
just after every exposure. You can also add time servers to it which are more
useful from your location.

Greg Crawford


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Bagnall Beach Observatory

http://www.nelsonbay.com/~gc/observatory.htm
 

> -----Original Message-----
> From: aavso-photometry-bounces at mira.aavso.org [mailto:aavso-photometry-
> bounces at mira.aavso.org] On Behalf Of Greg Crawford
> Sent: Thursday, 24 March 2005 8:27 AM
> To: aavso-photometry at mira.aavso.org
> Subject: RE: [Aavso-photometry] Re: Atomic Clock Synchronization -
> 
> My understanding is that the longer the ping time, the less accurate your time
> setting. Also, in Windows, the time progression may be altered by IRQ access,
> so
> that frequent time setting before and after an image download is essential.
> The
> inbuilt access in Windows XP may not be accurate enough for this.
> 
> The Minor Planet Centre requires time reported to 0.00001 of a day. I think
> that
> works out at 0.864 0f a second. (See the Guide to Minor Planet Astrometry
> http://cfa-www.harvard.edu/iau/info/Astrometry.html )
> 
> With all that in mind, the USNO time server may not be your best resource for
> two possible reasons: 1) Like me, you live in another part of the world, and
2)
> you have Internet delays in accessing it. I'd suggest you seek a time server
> with the lowest ping time from your location.
> 
> Also, bear in mind that AboutTime attempts to calculate the ping time and make
> adjustments for it.
> 
> Greg Crawford
> 
> 
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> Bagnall Beach Observatory
> 
> http://www.nelsonbay.com/~gc/observatory.htm
> 
> 
> > -----Original Message-----
> > From: aavso-photometry-bounces at mira.aavso.org [mailto:aavso-photometry-
> > bounces at mira.aavso.org] On Behalf Of Shankland, Paul D CDR U.S. Naval
> > Observatory
> > Sent: Thursday, 24 March 2005 6:36 AM
> > To: aavso-photometry at mira.aavso.org
> > Subject: [Aavso-photometry] Re: Atomic Clock Synchronization -
> >
> > Yes - NTP is the baseline for precise time on the web, and NTP.org is a good
> > start... but do be aware that, if you run WinXP, have a Router or a WiFi -
> any
> > one of these - (and didn't mess with the NTP settings) you are already
> pinging
> > our (USNO) or NIST's NTP servers so that yor PC clock is probably accurate
> to
> > within multi-millisec's (unless there exists a bottleneck - another story
> > itself)... See our clock at: http://tycho.usno.navy.mil/master.html. Also -
> if
> > you can get 1PPS ticks off the GPS NMEA stream (IOTA does alot of that if
> you
> > google for it) - we provide very (sub-microsecond) time to the constellation
> > (see: http://tycho.usno.navy.mil/gps.html and
> > http://tycho.usno.navy.mil/gpstt.html)
> >
> > I also recommend using: http://tycho.usno.navy.mil/ctime.html
> > - just note that our time is typically good to <10 nanoseconds, all NTP
> > transmissions suffer varying delays... unless you wanny buy time on TWSTT
> > (http://tycho.usno.navy.mil/twstt.html) <grin>
> >
> > Hope that adds to the info-
> > Best,
> > Paul
> >
> > ---
> > CDR Paul "Happy" Shankland, USN
> > Head, Plans & Requirements
> > U.S. Naval Observatory
> > Washington, D.C.
> >
> > USNO... Oldest US Government Scientific institution - and a cutting-edge
> > leader in.... Astrometry, The DoD & National Atomic Clock, The World's
> Precise
> > Time/PTTI, Atomic Fountain Clock Design/RFC/Cesium/LITE, TWSTT, Loran Time,
> > NTP, GPS Time and monitoring, IVS, TEM, the US Master Atomic Clock, Earth
> > Orientation, VLBI, ICRF, IERS, NEOS, Astronomical Applications, MICA,
> > SLAC/SLAP, NOVAS, RORF, QSO Reference framing, US Naval Correlator,
> Strategic
> > & Space Navigation & Ephimerides, Celestial Navigation/ACN, Nautical Almanac
> > Office, Celestial, Air and Nautical Almanacs, Naval Observatory Flagstaff,
> NP
> > Optical Interferometer, Parallax Program, IR, Wide & Narrow Angle
Astrometry,
> > Sloan digital Sky Survey, other Catalogs, NOMAD, USNO-B, WDS, UCAC, URAT,
> > Tycho-2, PMM, Photometry, Alt US Master Clock Colorado, OBSS, SIM Reference
> > Tie Science Team, TPF Support/Science Team
> >
> > Comm: 202-762-0108
> > paul.shankland at navy.mil
> > Work: http://www.usno.navy.mil/
> > Exoplanet astrophysics/dynamics/observations/searches/research:
> > http://www.ucolick.org/%7elaugh/GJ876____c.results.html
> > Full Member: http://www.aas.org/: DPS, DDA, HAD; AIP, IAU C41, ICHA, IUHPS,
> AL,
> > IDA
> > Carpe noctem!
> >
> >
> > Consider using NTP, which is a continual adjustment of the rate of time
> > and as such avoids discontinuities.
> >
> > http://www.ntp.org/
> >
> > Cheers,
> > Michael
> >
> > On Mar 22, 2005, at 4:41 PM, Keith Graham wrote:
> >
> > > Hi,
> > >
> > >
> > >
> > > S
> >
> > _______________________________________________
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> 
> 
> 
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