[Fwd: VOTimeSeries]

[Raúl Gutiérrez Sánchez]

Hello,

I would like to clarify the two aspects Francois is refering.

Francois Ochsenbein wrote:
> 
> ==> in the TimeObs, the value is a number of days since TimeZero.
>     The comment says that the value is an MJD value . 
> 

As said in the mail sent by Enrique, we developed the OMC SSAP service
using the the SSAP protocol Version 0.91 and Spectrum Data Model Version
0.95. There were a big work interpreting the two documents and trying to
produce a service consistent with them both. For the definition of the
time frame, three of the fields were Frame.Time.Type, which definition
is "Time type, always equal to MJD"; Frame.Time.Zero, which definition
is "Zero point of timescale in MJD, default 0" and
"Coverage.Location.Time.Value", which definition is "Midpoint of
Exposure, on JD scale". In the image sent by Roy, there is no reference
to the utype, but if you try the last URL Enrique sent, you will get the
actual VOTable the system returns, where:
TimeObs = Coverage.Location.Time.Value
TimeZero = Frame.Time.Zero = 51544.0

I am not an astronomer, but my understanding was that once specified the
Zero point, every time would be added automatically to this zero point
to obtain the corresponding MJD, if it is not the case, please, make me
know and I will correct it. Or maybe the problem is just with the
comment where, maybe, would be better to say "IJD" or "JD" instead of
"MJD"...



> ==> in the VOTable, the unit part of the Time field specifies that
>     the units are 's' (seconds). But the data values (1305.65557 etc)
>     are most likely days elapsed since TimeZero.

You are right, I have already corrected this.Thanks


Raúl



-- 
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Raúl Gutiérrez Sánchez      ( raul at laeff.inta.es )
Laboratorio de Astrofísica Espacial y Física Fundamental (www.laeff.inta.es)
European Space Astronomy Centre (ESAC)
Villafranca del Castillo - E-28691 Villanueva de la Cañada - Madrid - España
Tel.: 34 91 8131260    Fax.: 34 91 8131160
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