A Proposal for a TIMESYS Element in VOTable

[Arnold Rots]

The term TOPOCENTER has been used for several decades now to indicate the
location where the time is actually measured, i.e., at the
detector/telescope/observatory, regardless of whether the instrument is
located on the earth's surface or in space (or wherever else).
In both cases information is needed that specifies where that location is,
whether it is expressed as a fixed location wrt to the GEOCENTER (in any
type of spatial coordinate system) or as an (orbit) ephemeris.

Cheers,

  - Arnold

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Arnold H. Rots                                          Chandra X-ray
Science Center
Smithsonian Astrophysical Observatory                   tel:  +1 617 496
7701
60 Garden Street, MS 67                                      fax:  +1 617
495 7356
Cambridge, MA 02138
arots at cfa.harvard.edu
USA
http://hea-www.harvard.edu/~arots/
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On Wed, Oct 31, 2018 at 3:55 PM Tom McGlynn <tom.mcglynn at nasa.gov> wrote:

> It seems to me that this makes no accommodation for satellites where the
> reference position is variable but not
> unknown.  The definition of topocentric is according to my dictionary:
> "**relating to, measured from, or as if observed from a particular point
> on the earth's surface *: *having or relating to such a point as origin"
> so TOPOCENTER is fine for earth based observations (though there are
> balloons that move quite a bit during an observation campaign) but it
> would be a stretch to use it for satellites.  I wouldn't want to say
> UNKNOWN though.    Maybe SATELLITE or VARIABLE? Lots of HEASARC data
> have times that are measured at the satellite -- and that includes lots
> of the GRB detecting satellites for which this kind of feature would be
> very nice.
>
>      Tom McG.
>
> AdaNebot wrote:
> > Dear All,
> >
> > A Note entitled “*A Proposal for a TIMESYS Element in VOTable*” can be
> > found under:
> >
> > http://ivoa.net/documents/Notes/TimeSys/
> >
> >
> > Thanks for taking the time to read this document,
> >
> > Happy reading!
> >
> > See you in College Park,
> > Ada Nebot
> > TDIG Chair
> >
>
>
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