These are all OPEN LOOP corrections. They are better than nothing, but nowhere near as good as properly implemented auto-guiding which is closed loop.
They are certainly not as good as even the simplest Adaptive Optics utilizing only a Tip-Tilt tracker. -John ================== > One needs to know the local apparent sidereal time to aid initial > acquisition of the target. > Periodic error correction and using an autoguider are of little or no > use for this operation. > > However correction for encoder error axis non orthogonality, encoder > eccentricity and bending of the telescope tube an the mount may be > required. > A pointing model for the telescope is derived from the pointing (not > tracking errors) errors for a set of target objects uniformly > distributed over the sky. > For further details see: > > http://www.tpsoft.demon.co.uk/ > > Bruce > > Jim King wrote: >> I'm not sure your friend needs the time at all. Telescope tracking >> mounts have a periodic error due to non-perfect mechanical parts. The >> usual way to remove this error is to "train" the mount by manually >> guiding it through one or more periods, or - probably more common >> these days - use an optical autoguider. >> >> Jim >> >> On 1:59 PM, Brooke Clarke wrote: >>> Hi Brian: >>> >>> Why? Do you just want to see the sidereal time on a display or do >>> you need a digital output? >>> The Spark Fun "serial enabled" displays use what's called a "back >>> pack" that has the PIC 16F88 uC and it's used to do serial data to >>> LCD parallel data can control lines. I've made some clocks using >>> that chip. >>> http://www.prc68.com/I/PIC16F88.shtml >>> http://www.prc68.com/I/PRC68COM.shtml#07092006 >>> >>> A friend is setting up an observatory where the pointing accuracy of >>> the telescope mount is specified as " 7 arcseconds or less >>> peak-to-peak periodic error before correction". Much better after >>> correction. That implies he needs to know what time it is within >>> tens of milliseconds. >>> http://www.prc68.com/I/StellarTime.shtml#StrMov >>> We looked into different ways to get the time into his computer to >>> that accuracy and NTP looks like it will fill the bill, so a GPS >>> receiver may not be required. >>> >>> Have Fun, >>> >>> Brooke Clarke >>> http://www.PRC68.com >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
