Re: [LEAPSECS] Telescope pointing and UTC

From: Markus Kuhn <Markus.Kuhn_at_CL.CAM.AC.UK>
Date: Thu, 30 Jan 2003 20:53:52 +0000

Steve Allen wrote on 2003-01-30 20:17 UTC:
> The specifications for the automatic telescope call for an object to
> appear within 10 arcsec of the field center after a slew. This is
> congruent with what the telescope engineers can do with the flexure
> and hysteresis, but it obviously requires UT1 good to about 0.66 s for
> targets on the equator. Therefore we do need DUT1, but not to more
> accuracy than it is provided. Higher cost telescopes may be able to
> demand tighter specifications.

In addition, if you have a readily aligned telescope, DUT1 to 100 ms
should be more than exact enough to locate a bright guide star. Then let
the system make a quick CCD exposure of that and derive DUT1 with the
needed precision by looking at the coordinates of the brightest peak on
this image.

Even amateur equipment with CCD tracker does all that today fully
automatically, including the figuring out the telescope's alignment:

In the various surveys among professional observatories that have been
reported here, have the manufacturers of microprocessor-controlled
amateur telescopes (which today typically come with integrated GPS
receivers) been asked, what |UT1-UTC| > 0.9 s would means for the many
thousands of systems that they have already sold?


Markus Kuhn, Computer Lab, Univ of Cambridge, GB | __oo_O..O_oo__
Received on Thu Jan 30 2003 - 12:53:59 PST

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