xearth...

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Miguel Simon

xearth...

Post by Miguel Simon » Tue Oct 28, 2003 4:44 am

Hi...

I downloaded the xearth software from

http://ag.qnx.org.ru/xearth/index.html

and it is pretty cool. I have a question...

I want to set the view as the orbit of the ISS which have
(http://www.hq.nasa.gov/osf/station/viewing/issvis.html):

Period (min)..............................92.14
Inclination (degrees).....................51.6307

I set these parameters in the xearth viewpoint-properties, but I am
afraid that I do not get what I want. In other words, the xearth does
not rotate as expected. Did I misunderstand how this works?

Thanks.

Regards...

Miguel.

peter

Re: xearth...

Post by peter » Tue Oct 28, 2003 5:44 pm

Miguel Simon wrote:
Hi...

I downloaded the xearth software from

http://ag.qnx.org.ru/xearth/index.html

and it is pretty cool. I have a question...

I want to set the view as the orbit of the ISS which have
(http://www.hq.nasa.gov/osf/station/viewing/issvis.html):

Period (min)..............................92.14
Inclination (degrees).....................51.6307

Did you synch your clock w/ a time server?
To my knowledge, you need the SGP4 calculation model to track an object
which is orbiting near earth.
The period is nearly constant but the inclination is not.
A prediction only w/ the period and dec. is only valid for 1 or 2 hours.
If you use the TLE from NORAD w/ SGP4 (SGP3 is also ok), you can track
each object in realtime. The TLE is updated every day (or every hour, if
the STS is on its way).
Bad news.....SGP3 and SGP4 was written in Fortran and then ported to C
(more goto's than linenumbers ;-).
happy tracking, cheers, peter

I set these parameters in the xearth viewpoint-properties, but I am
afraid that I do not get what I want. In other words, the xearth does
not rotate as expected. Did I misunderstand how this works?

Thanks.

Regards...

Miguel.

peter

Re: xearth...

Post by peter » Tue Oct 28, 2003 9:35 pm

Period is taken in hours I think (1.535667 hours)
I don't know how xearth takes the RAAN of the orbit track :-(.

peter wrote:
Miguel Simon wrote:

Hi...

I downloaded the xearth software from

http://ag.qnx.org.ru/xearth/index.html

and it is pretty cool. I have a question...

I want to set the view as the orbit of the ISS which have
(http://www.hq.nasa.gov/osf/station/viewing/issvis.html):

Period (min)..............................92.14
Inclination (degrees).....................51.6307

Did you synch your clock w/ a time server?

To my knowledge, you need the SGP4 calculation model to track an object
which is orbiting near earth.
The period is nearly constant but the inclination is not.
A prediction only w/ the period and dec. is only valid for 1 or 2 hours.
If you use the TLE from NORAD w/ SGP4 (SGP3 is also ok), you can track
each object in realtime. The TLE is updated every day (or every hour, if
the STS is on its way).
Bad news.....SGP3 and SGP4 was written in Fortran and then ported to C
(more goto's than linenumbers ;-).
happy tracking, cheers, peter


I set these parameters in the xearth viewpoint-properties, but I am
afraid that I do not get what I want. In other words, the xearth does
not rotate as expected. Did I misunderstand how this works?

Thanks.

Regards...

Miguel.

Miguel Simon

Re: xearth...

Post by Miguel Simon » Wed Oct 29, 2003 11:13 pm

Hhi Peter...

Thanks for your help here. I think that _period_ is taken in days,
actually, but I am not sure. I divided the posted ISS orbital period (in
min) by the total minutes in a day, and it seems to work properly.

Thanks for your help.

Regards...

Miguel.


peter wrote:
Period is taken in hours I think (1.535667 hours)
I don't know how xearth takes the RAAN of the orbit track :-(.

peter wrote:

Miguel Simon wrote:

Hi...

I downloaded the xearth software from

http://ag.qnx.org.ru/xearth/index.html

and it is pretty cool. I have a question...

I want to set the view as the orbit of the ISS which have
(http://www.hq.nasa.gov/osf/station/viewing/issvis.html):

Period (min)..............................92.14
Inclination (degrees).....................51.6307

Did you synch your clock w/ a time server?

To my knowledge, you need the SGP4 calculation model to track an object
which is orbiting near earth.
The period is nearly constant but the inclination is not.
A prediction only w/ the period and dec. is only valid for 1 or 2 hours.
If you use the TLE from NORAD w/ SGP4 (SGP3 is also ok), you can track
each object in realtime. The TLE is updated every day (or every hour,
if the STS is on its way).
Bad news.....SGP3 and SGP4 was written in Fortran and then ported to C
(more goto's than linenumbers ;-).
happy tracking, cheers, peter


I set these parameters in the xearth viewpoint-properties, but I am
afraid that I do not get what I want. In other words, the xearth
does not rotate as expected. Did I misunderstand how this works?

Thanks.

Regards...

Miguel.


Peter weber

Re: xearth...

Post by Peter weber » Thu Oct 30, 2003 5:30 pm

Miguel Simon wrote:
Hhi Peter...

Thanks for your help here. I think that _period_ is taken in days,
actually, but I am not sure. I divided the posted ISS orbital period (in
min) by the total minutes in a day, and it seems to work properly.
How do you set the starting point (RAAN) of the orbit
you want to track ?
It seems that xearth for Photon has no UDP connection to the 'predict
server' like the original xearth for X11. :-(
However, I ported 'predict 2.2.2' to RTP6.2.1A. If someone
is interrested, I can post the archive here.
cheers,peter
Thanks for your help.

Regards...

Miguel.


peter wrote:

Period is taken in hours I think (1.535667 hours)
I don't know how xearth takes the RAAN of the orbit track :-(.

peter wrote:

Miguel Simon wrote:

Hi...

I downloaded the xearth software from

http://ag.qnx.org.ru/xearth/index.html

and it is pretty cool. I have a question...

I want to set the view as the orbit of the ISS which have
(http://www.hq.nasa.gov/osf/station/viewing/issvis.html):

Period (min)..............................92.14
Inclination (degrees).....................51.6307

Did you synch your clock w/ a time server?

To my knowledge, you need the SGP4 calculation model to track an object
which is orbiting near earth.
The period is nearly constant but the inclination is not.
A prediction only w/ the period and dec. is only valid for 1 or 2 hours.
If you use the TLE from NORAD w/ SGP4 (SGP3 is also ok), you can
track each object in realtime. The TLE is updated every day (or every
hour, if the STS is on its way).
Bad news.....SGP3 and SGP4 was written in Fortran and then ported to
C (more goto's than linenumbers ;-).
happy tracking, cheers, peter


I set these parameters in the xearth viewpoint-properties, but I am
afraid that I do not get what I want. In other words, the xearth
does not rotate as expected. Did I misunderstand how this works?

Thanks.

Regards...

Miguel.



Warren Deitch

Re: xearth...

Post by Warren Deitch » Thu Oct 30, 2003 10:02 pm

I am interested !

Peter weber wrote:
Miguel Simon wrote:

Hhi Peter...

Thanks for your help here. I think that _period_ is taken in days,
actually, but I am not sure. I divided the posted ISS orbital period
(in min) by the total minutes in a day, and it seems to work properly.

How do you set the starting point (RAAN) of the orbit
you want to track ?
It seems that xearth for Photon has no UDP connection to the 'predict
server' like the original xearth for X11. :-(
However, I ported 'predict 2.2.2' to RTP6.2.1A. If someone
is interrested, I can post the archive here.
cheers,peter


Thanks for your help.

Regards...

Miguel.


peter wrote:

Period is taken in hours I think (1.535667 hours)
I don't know how xearth takes the RAAN of the orbit track :-(.

peter wrote:

Miguel Simon wrote:

Hi...

I downloaded the xearth software from

http://ag.qnx.org.ru/xearth/index.html

and it is pretty cool. I have a question...

I want to set the view as the orbit of the ISS which have
(http://www.hq.nasa.gov/osf/station/viewing/issvis.html):

Period (min)..............................92.14
Inclination (degrees).....................51.6307

Did you synch your clock w/ a time server?

To my knowledge, you need the SGP4 calculation model to track an object
which is orbiting near earth.
The period is nearly constant but the inclination is not.
A prediction only w/ the period and dec. is only valid for 1 or 2
hours.
If you use the TLE from NORAD w/ SGP4 (SGP3 is also ok), you can
track each object in realtime. The TLE is updated every day (or
every hour, if the STS is on its way).
Bad news.....SGP3 and SGP4 was written in Fortran and then ported to
C (more goto's than linenumbers ;-).
happy tracking, cheers, peter


I set these parameters in the xearth viewpoint-properties, but I am
afraid that I do not get what I want. In other words, the xearth
does not rotate as expected. Did I misunderstand how this works?

Thanks.

Regards...

Miguel.




Bill Caroselli

Re: xearth...

Post by Bill Caroselli » Fri Oct 31, 2003 4:45 pm

In like two or three sentences, what is xearth?

Peter

Re: xearth...

Post by Peter » Fri Oct 31, 2003 7:00 pm

http://www.cs.colorado.edu/~tuna/xearth/

"Bill Caroselli" <qtps@earthlink.net> schrieb im Newsbeitrag
news:bnu3io$4uv$1@inn.qnx.com...
> In like two or three sentences, what is xearth?

peter

Re: xearth...

Post by peter » Fri Oct 31, 2003 8:17 pm

Miguel,
I found the following in the man page of the xearth.

The position specifier keyword 'orbit' should be followed by two
arguments, interpreted as numerical values indicating the period
(in hours) and orbital inclination (in decimal degrees) of a
simple circular orbit; the viewing position follows this orbit.
Astute readers will surely note that these parameters are not
sufficient to uniquely specify a single circular orbit. This
problem is solved by limiting the space of possible orbits to
those positioned over 0 degrees latitude, 0 degrees longitude at
time zero (the Un*x epoch, see time(3)).

Miguel Simon wrote:
Hhi Peter...

Thanks for your help here. I think that _period_ is taken in days,
actually, but I am not sure. I divided the posted ISS orbital period (in
min) by the total minutes in a day, and it seems to work properly.

Thanks for your help.

Regards...

Miguel.


peter wrote:

Period is taken in hours I think (1.535667 hours)
I don't know how xearth takes the RAAN of the orbit track :-(.

peter wrote:

Miguel Simon wrote:

Hi...

I downloaded the xearth software from

http://ag.qnx.org.ru/xearth/index.html

and it is pretty cool. I have a question...

I want to set the view as the orbit of the ISS which have
(http://www.hq.nasa.gov/osf/station/viewing/issvis.html):

Period (min)..............................92.14
Inclination (degrees).....................51.6307

Did you synch your clock w/ a time server?

To my knowledge, you need the SGP4 calculation model to track an object
which is orbiting near earth.
The period is nearly constant but the inclination is not.
A prediction only w/ the period and dec. is only valid for 1 or 2 hours.
If you use the TLE from NORAD w/ SGP4 (SGP3 is also ok), you can
track each object in realtime. The TLE is updated every day (or every
hour, if the STS is on its way).
Bad news.....SGP3 and SGP4 was written in Fortran and then ported to
C (more goto's than linenumbers ;-).
happy tracking, cheers, peter


I set these parameters in the xearth viewpoint-properties, but I am
afraid that I do not get what I want. In other words, the xearth
does not rotate as expected. Did I misunderstand how this works?

Thanks.

Regards...

Miguel.



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