Description of L2 in STC

[Roy Williams]

On 04/18/2011 12:02 AM, Hervé Wozniak wrote:

> L2 point is 1,500,000 km not 150,000... just a factor 10 father ;-)

Herve
You are right about the distance from Earth to L2, but there is no 
mistake below.  What is wanted for these observatories is a *region* 
around L2 of about 150,000 km diameter, since that is the diameter of 
the potential well in which the complex orbit happens.

Since STC already defines the words below, perhaps we should say in the 
VOEvent document that they can say L2EARTHSUN or something like that. I 
just wondered if there is anything already in STC, since I didn't see it 
there.

In that case, do we also need L2MOONEARTH? Is there anyone observing 
from there?
Roy


GEOSURFACE - any location on the surface of the earth
GEOLEO - any location in Low Earth Orbit (altitude<700 km)
GEOGSO - any location within Geostationary orbit altitude
GEONBH - any location within 50,000 km of the geocenter
GEOLUN - any location within the Moon's orbit



> And this is only a rough estimate since a satellite moves along an orbit
> around this point (a Lissajous for Herschel, another kind for JWST :
> http://www.stsci.edu/jwst/overview/design/orbit.html )
>
>
> Cheers,
> Hervé
>
>
> Le 16/04/2011 01:05, Roy Williams écrivait :
>
>> Arnold and DM group
>> Can you advise on Wil's question, that has come up on the VOEvent RFC
>> page?
>> Thank you
>> Roy
>>
>> -------- Original Message --------
>> Subject: Re: Can you help with VOEvent2?
>> Date: Thu, 14 Apr 2011 11:49:04 +0200
>> From: William O'Mullane <womullan at sciops.esa.int>
>> To: Roy Williams <roy.williams at ligo.org>
>> CC: Nicholas A Walton <naw at ast.cam.ac.uk>, Lukasz Wyrzykowski
>> <wyrzykow at ast.cam.ac.uk>, "R.Burgon" <r.burgon at open.ac.uk>
>>
>> in 3.4.2 ObservatoryLocation
>> You should add "L2 = within 150000 KM of Earth Sun Lagrange Point 2" or
>> something there are enough missions going out there even if you suggest
>> space missions can construct their own complex location later.
>>
>