[Spice_discussion] Re: [Spice_announce] Geometry Engine

[Ralf Srama]

I agree. We often need:

Distance (range) from Saturn / other body
Altitude above ring plane
range of latitude (inclination)
range of longitude
time from Ring Plane Xing
time from satellite orbit Xing

Great idea!

Ralf

On Monday 24 February 2003 16:54, Crary, Frank wrote:
> All of the geometric events in that list seem to involve three bodies (i.e.
> angular separation between body 1 and body 2, as seen from a spacecraft.) I
> think it would be very convenient for particles and fields instruments to
> have simple, 2 body events (e.g. range between spacecraft and planet body
> center less than X or planetocentric latitude of spacecraft greater than
> Y.)
>
>
> Frank
>
> -----Original Message-----
> From: Diane Conner [mailto:Diane.Conner at jpl.nasa.gov]
> Sent: Friday, February 21, 2003 12:19 PM
> To: spice at dcs04.jpl.nasa.gov
> Subject: Fwd: [Spice_announce] Geometry Engine
>
> >Date: Wed, 19 Feb 2003 09:00:33 -0800
>
> From: Lee Elson <Lee.Elson at jpl.nasa.gov>
>
> >Subject: [Spice_announce] Geometry Engine
> >Sender: spice_announce-admin at naif.jpl.nasa.gov
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> >
> >As part of an ongoing effort to increase the functionality of the
> >SPICE Toolkit, we at NAIF are planning the development of SPICELIB
> >routines that will allow the user to determine time windows or
> >"schedules" when certain geometric constraints are met. To make this
> >development process as efficient as possible, we'd like to determine
> >which geometric constraints would offer the most "bang for the buck"
> >in terms of useful functionality. Listed below are brief
> >descriptions of what we've come up with (in a loose arrangement of
> >decreasing priority):
> >
> >1)"Distance" -- determine time intervals during which the apparent
> >distance between 2 specified bodies, as viewed from a specified
> >observing body, satisfies a specified constraint (e.g. less than,
> >equal to, greater than, between values)
> >
> >2)"Phase"-- determine time intervals during which the apparent
> >observer-target-Sun angle satisfies a specified constraint.
> >
> >3)"Eclipse"-- determine time intervals during which one body is
> >eclipsed by another as viewed by an observer.
> >
> >4)"Occultation/transit"-- determine time intervals during which one
> >body is occulted/transited by another as viewed by an observer.
> >
> >5)"Time from periapsis/apoapsis"-- determine time intervals during
> >which a body in orbit is within a specified time interval from
> >periapsis/apoapsis.
> >
> >6)"Elevation"-- determine time intervals during which the elevation
> >of an object, in a specified reference frame, satisfies a specified
> >constraint.
> >
> >7)"Viewed Latitude/longitude"-- determine time intervals during
> >which a viewed location (latitude/longitude) satisfies a specified
> >constraint.
> >
> >8)"Nadir separation"-- determine time intervals during which the
> >angle between an observed object and the nadir direction satisfies a
> >specified constraint.
> >
> >9)"Separation"-- determine time intervals during which the angular
> >separation of 2 bodies (as seen by an observer) satisfies a
> >specified constraint.
> >
> >10)"Incidence/emission/solar longitude"-- determine time intervals
> >during which the incidence/emission/solar longitude angle satisfies
> >a specified constraint.
> >
> >11)"Orbital longitude"-- determine time intervals during which the
> >orbital longitude of an object, relative to an observer, satisfies a
> >specified constraint.
> >
> >12)"Angular velocity"-- determine time intervals during which the
> >angular velocity of one object relative to another satisfies a
> >specified constraint.
> >
> >13)"Apparent diameter"-- determine time intervals during which the
> >apparent diameter of a body satisfies a specified constraint.
> >
> >14)"Elongation"-- determine time intervals during which the
> >elongation (angular separation of a body from the sun) of a body
> >satisfies a specified constraint.
> >
> >15)"Relative velocity"-- determine time intervals during which the
> >velocity of one body relative to another satisfies a specified
> >constraint.
> >
> >16) "User supplied"-- determine time intervals during which a
> >function provided by the user satisfies a specified constraint.
> >
> >In addition to the time oriented "windows/schedules" discussed
> >above, it is possible (but more work) to have other solutions. An
> >example might be to find a range of viewed latitudes and longitudes
> >for a specified time window.
> >
> >The main purpose of this note is to solicit your input. Are the 16
> >constraints listed above of any use to you? Are there others that
> >would be more useful?
> >
> >Regards,
> >Lee Elson
> >Lee.Elson at jpl.nasa.gov
> >818-354-4223
> >
> >
> >
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*** Ralf Srama   Max-Planck-Institut für Kernphysik ***
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