in reguards to ocultations, woud it be easier to convert everything into polar coordinates then the positions of the stars and the moon becomes an angle and a radius. everywhere that the angles of the stars and the moon are the same and the radii are the same is an occultation. the thing becomes geometry without such a need for time. if you think of it as a graph you can visualise all the stars in the moons path as a 'donut' and the moons path (say for aguments sake, over a year) would make a spirograph patern. everywhere where the spirograph patern hits a star would be an occultation.<br><br><b><i>kstars-devel-request@kde.org</i></b> wrote:<blockquote class="replbq" style="border-left: 2px solid rgb(16, 16, 255); margin-left: 5px; padding-left: 5px;"> Send Kstars-devel mailing list submissions to<br> kstars-devel@kde.org<br><br>To subscribe or unsubscribe via the World Wide Web, visit<br> https://mail.kde.org/mailman/listinfo/kstars-devel<br>or, via email, send a message
with subject or body 'help' to<br> kstars-devel-request@kde.org<br><br>You can reach the person managing the list at<br> kstars-devel-owner@kde.org<br><br>When replying, please edit your Subject line so it is more specific<br>than "Re: Contents of Kstars-devel digest..."<br><br><br>Today's Topics:<br><br> 1. Re: Kstars-devel Digest, Vol 46, Issue 8 (Jason Harris)<br> 2. Re: Kstars-devel Digest, Vol 46, Issue 8 (Akarsh Simha)<br><br><br>----------------------------------------------------------------------<br><br>Message: 1<br>Date: Mon, 4 Jun 2007 07:57:17 -0700<br>From: Jason Harris <jharris@30doradus.org><br>Subject: Re: [Kstars-devel] Kstars-devel Digest, Vol 46, Issue 8<br>To: KStars Development Mailing List <kstars-devel@kde.org><br>Message-ID: <200706040757.18055.kstars@30doradus.org><br>Content-Type: text/plain; charset="iso-8859-1"<br><br>Hello,<br><br>I think you're right; the only way to predict occultation events is to advance <br>the time in small
steps, and check whether the angular separation of the <br>bodies is smaller than their angular size.<br><br>However, there are ways to speed up the process. You can take a large <br>timestep, and see if a linear approximation of the body's path carries it <br>near any bright stars. If so, then you can estimate when a potential <br>occultation would occur, set the clock to that time, and check the position. <br>The new position will either (a) be in occultation, (b) exclude the <br>possibility of occultation, or (c) be placed "before" or "after" a potential <br>occultation. In case (c), we would predict a new occultation time based on <br>the body's positions at known times bracketing the target star, set the clock <br>to that time and try again until we got (a) or (b).<br><br>This is called a "predictor-corrector" search. It is much faster than just <br>advancing the clock by small steps over the whole interval. When the target <br>object that may be occulted is
another planetary body (rather than a star), <br>the calculation will be more complicated, but the general strategy still <br>applies, I think.<br><br>regards,<br>Jason<br><br>On Monday 04 June 2007 02:43, Akarsh Simha wrote:<br>> I'm sorry... please ignore my previous reply in this thread - it makes<br>> no sense whatever and I was confused while writing that.<br>><br>> How would one predict occultations though?<br>> The only way I can think of is keep increasing (or decreasing) the<br>> time in certain small steps and check if the occultation is going to<br>> happen. But that will be extremely slow, or so I think.<br>><br>> A modification I see to the above is that we ask the user to input a<br>> time range and then do some kind of a smart search which also applies<br>> some logic to guess an estimate and then search around that.<br>><br>> Any better ideas?<br>><br>> On 5/28/07, Akarsh Simha <akarshsimha@gmail.com>
wrote:<br>> > Ok. Thanks for that. I guess I should be able to do it easily if the<br>> > heliocentric longitudes are computed somewhere. I'll take a look into<br>> > this.<br>> ><br>> > On 5/28/07, brian hurren <brianhurren@yahoo.com> wrote:<br>> > > Akarsh, have a go at writing a class for occultations.<br>> > ><br>> > > kstars-devel-request@kde.org wrote:<br>> > > Send Kstars-devel mailing list submissions to<br>> > > kstars-devel@kde.org<br>> > ><br>> > > To subscribe or unsubscribe via the World Wide Web, visit<br>> > > https://mail.kde.org/mailman/listinfo/kstars-devel<br>> > > or, via email, send a message with subject or body 'help' to<br>> > > kstars-devel-request@kde.org<br>> > ><br>> > > You can reach the person managing the list at<br>> > > kstars-devel-owner@kde.org<br>> > ><br>> > > When replying,
please edit your Subject line so it is more specific<br>> > > than "Re: Contents of Kstars-devel digest..."<br>> > ><br>> > ><br>> > > Today's Topics:<br>> > ><br>> > > 1. Quite a few bugs (Akarsh Simha)<br>> > ><br>> > ><br>> > > ----------------------------------------------------------------------<br>> > ><br>> > > Message: 1<br>> > > Date: Sun, 27 May 2007 00:55:29 +0530<br>> > > From: "Akarsh Simha"<br>> > > Subject: [Kstars-devel] Quite a few bugs<br>> > > To: kstars-devel@kde.org<br>> > > Message-ID:<br>> > ><br>> > > Content-Type: text/plain; charset=ISO-8859-1; format=flowed<br>> > ><br>> > > Hello<br>> > ><br>> > > I am new to this mailing list. I am Akarsh Simha, a student of<br>> > > Physics, from Bangalore, India and an amateur astronomer. Am not
very<br>> > > well acquainted with Linux programming, though I can do some coding in<br>> > > C++.<br>> > ><br>> > > I was looking through KStars and found a few bugs, which I'm posting<br>> > > here:<br>> > ><br>> > > 1. The highlighted constellation boundaries do not coincide with the<br>> > > actual boundaries when zoomed in.<br>> > > 2. Io and Europa are not displaying correctly<br>> > > 3. Constellation names in the object identification that pops up when<br>> > > you right click on the object shows the constellations' three letter<br>> > > abbreviations instead of the name.<br>> > > 4. I opened the Object Details dialog and clicked on the image to do<br>> > > an image search. After I closed the image search dialog, I got a<br>> > > segmentation fault. I have saved the Backtrace that KDE generated.<br>> > > 5. It seems like
there is no display symbol for asteroids. I feel that<br>> > > the symbol for comets need to be something more meaningful.<br>> > ><br>> > > Regards,<br>> > > Akarsh<br>> > ><br>> > ><br>> > > ------------------------------<br>> > ><br>> > > _______________________________________________<br>> > > Kstars-devel mailing list<br>> > > Kstars-devel@kde.org<br>> > > https://mail.kde.org/mailman/listinfo/kstars-devel<br>> > ><br>> > ><br>> > > End of Kstars-devel Digest, Vol 46, Issue 8<br>> > > *******************************************<br>> > ><br>> > ><br>> > ><br>> > > ________________________________<br>> > > Ready for the edge of your seat? Check out tonight's top picks on<br>> > > Yahoo! TV.<br>> > ><br>> > ><br>> > >
_______________________________________________<br>> > > Kstars-devel mailing list<br>> > > Kstars-devel@kde.org<br>> > > https://mail.kde.org/mailman/listinfo/kstars-devel<br>> ><br>> > --<br>> > Regards,<br>> > Akarsh<br>> > http://www.bas.org.in<br>> > http://www.nascent-technologies.com<br><br>-- <br>KStars: http://edu.kde.org/kstars<br>Community Forums: http://kstars.30doradus.org<br><br><br>------------------------------<br><br>Message: 2<br>Date: Mon, 4 Jun 2007 22:36:02 +0530<br>From: "Akarsh Simha" <akarshsimha@gmail.com><br>Subject: Re: [Kstars-devel] Kstars-devel Digest, Vol 46, Issue 8<br>To: "KStars Development Mailing List" <kstars-devel@kde.org><br>Message-ID:<br> <c00c02910706041006h7d93b9a3xaf49f0951b5a83c9@mail.gmail.com><br>Content-Type: text/plain; charset=ISO-8859-1; format=flowed<br><br>Hi.<br><br>I see that this logic works very fast.<br><br>But how would you be sure that the
algorithm hasn't missed one of<br>those possible occultations?<br><br>And how do we keep these "occultable" objects, i.e. bright stars,<br>planets? Do we put them in a QList or QHash or some such thing?<br><br>How I picturize the occultation module is that it should be able to<br>predict occultations of a fixed body against a number of possible<br>other bodies. These other bodies could be bright stars, other planets,<br>or DSOs. I should also be able to select a fixed object for the second<br>object, like, for instance ask when the next occultation of Moon and<br>Mars will be. I should also be able to give time ranges for prediction<br>of occultations.<br><br>I also feel it'd be nice if we could extend the occultations tool to<br>also do rendezvous predictions, like the recent Comet 73P and Ring<br>Nebula etc. I picturize this as an "occultation" where the angular<br>separation between the objects is set to something arbitrary, say the<br>FOV of your telescope. That could
help you predict, for instance, when<br>Comet 2P/Encke and Andromeda Galaxy would again appear in the same FOV<br>in the telescope, which would be a wonderful and unique extension to<br>the same occultation tool.<br><br>Any ideas?<br><br><br><br>On 6/4/07, Jason Harris <jharris@30doradus.org> wrote:<br>> Hello,<br>><br>> I think you're right; the only way to predict occultation events is to advance<br>> the time in small steps, and check whether the angular separation of the<br>> bodies is smaller than their angular size.<br>><br>> However, there are ways to speed up the process. You can take a large<br>> timestep, and see if a linear approximation of the body's path carries it<br>> near any bright stars. If so, then you can estimate when a potential<br>> occultation would occur, set the clock to that time, and check the position.<br>> The new position will either (a) be in occultation, (b) exclude the<br>> possibility of occultation,
or (c) be placed "before" or "after" a potential<br>> occultation. In case (c), we would predict a new occultation time based on<br>> the body's positions at known times bracketing the target star, set the clock<br>> to that time and try again until we got (a) or (b).<br>><br>> This is called a "predictor-corrector" search. It is much faster than just<br>> advancing the clock by small steps over the whole interval. When the target<br>> object that may be occulted is another planetary body (rather than a star),<br>> the calculation will be more complicated, but the general strategy still<br>> applies, I think.<br>><br>> regards,<br>> Jason<br>><br>> On Monday 04 June 2007 02:43, Akarsh Simha wrote:<br>> > I'm sorry... please ignore my previous reply in this thread - it makes<br>> > no sense whatever and I was confused while writing that.<br>> ><br>> > How would one predict occultations though?<br>> >
The only way I can think of is keep increasing (or decreasing) the<br>> > time in certain small steps and check if the occultation is going to<br>> > happen. But that will be extremely slow, or so I think.<br>> ><br>> > A modification I see to the above is that we ask the user to input a<br>> > time range and then do some kind of a smart search which also applies<br>> > some logic to guess an estimate and then search around that.<br>> ><br>> > Any better ideas?<br>> ><br>> > On 5/28/07, Akarsh Simha <akarshsimha@gmail.com> wrote:<br>> > > Ok. Thanks for that. I guess I should be able to do it easily if the<br>> > > heliocentric longitudes are computed somewhere. I'll take a look into<br>> > > this.<br>> > ><br>> > > On 5/28/07, brian hurren <brianhurren@yahoo.com> wrote:<br>> > > > Akarsh, have a go at writing a class for occultations.<br>> > >
><br>> > > > kstars-devel-request@kde.org wrote:<br>> > > > Send Kstars-devel mailing list submissions to<br>> > > > kstars-devel@kde.org<br>> > > ><br>> > > > To subscribe or unsubscribe via the World Wide Web, visit<br>> > > > https://mail.kde.org/mailman/listinfo/kstars-devel<br>> > > > or, via email, send a message with subject or body 'help' to<br>> > > > kstars-devel-request@kde.org<br>> > > ><br>> > > > You can reach the person managing the list at<br>> > > > kstars-devel-owner@kde.org<br>> > > ><br>> > > > When replying, please edit your Subject line so it is more specific<br>> > > > than "Re: Contents of Kstars-devel digest..."<br>> > > ><br>> > > ><br>> > > > Today's Topics:<br>> > > ><br>> > > > 1. Quite a few bugs (Akarsh
Simha)<br>> > > ><br>> > > ><br>> > > > ----------------------------------------------------------------------<br>> > > ><br>> > > > Message: 1<br>> > > > Date: Sun, 27 May 2007 00:55:29 +0530<br>> > > > From: "Akarsh Simha"<br>> > > > Subject: [Kstars-devel] Quite a few bugs<br>> > > > To: kstars-devel@kde.org<br>> > > > Message-ID:<br>> > > ><br>> > > > Content-Type: text/plain; charset=ISO-8859-1; format=flowed<br>> > > ><br>> > > > Hello<br>> > > ><br>> > > > I am new to this mailing list. I am Akarsh Simha, a student of<br>> > > > Physics, from Bangalore, India and an amateur astronomer. Am not very<br>> > > > well acquainted with Linux programming, though I can do some coding in<br>> > > > C++.<br>> > > ><br>> > > > I
was looking through KStars and found a few bugs, which I'm posting<br>> > > > here:<br>> > > ><br>> > > > 1. The highlighted constellation boundaries do not coincide with the<br>> > > > actual boundaries when zoomed in.<br>> > > > 2. Io and Europa are not displaying correctly<br>> > > > 3. Constellation names in the object identification that pops up when<br>> > > > you right click on the object shows the constellations' three letter<br>> > > > abbreviations instead of the name.<br>> > > > 4. I opened the Object Details dialog and clicked on the image to do<br>> > > > an image search. After I closed the image search dialog, I got a<br>> > > > segmentation fault. I have saved the Backtrace that KDE generated.<br>> > > > 5. It seems like there is no display symbol for asteroids. I feel that<br>> > > > the symbol for
comets need to be something more meaningful.<br>> > > ><br>> > > > Regards,<br>> > > > Akarsh<br>> > > ><br>> > > ><br>> > > > ------------------------------<br>> > > ><br>> > > > _______________________________________________<br>> > > > Kstars-devel mailing list<br>> > > > Kstars-devel@kde.org<br>> > > > https://mail.kde.org/mailman/listinfo/kstars-devel<br>> > > ><br>> > > ><br>> > > > End of Kstars-devel Digest, Vol 46, Issue 8<br>> > > > *******************************************<br>> > > ><br>> > > ><br>> > > ><br>> > > > ________________________________<br>> > > > Ready for the edge of your seat? Check out tonight's top picks on<br>> > > > Yahoo! TV.<br>> > > ><br>> > > ><br>> > > >
_______________________________________________<br>> > > > Kstars-devel mailing list<br>> > > > Kstars-devel@kde.org<br>> > > > https://mail.kde.org/mailman/listinfo/kstars-devel<br>> > ><br>> > > --<br>> > > Regards,<br>> > > Akarsh<br>> > > http://www.bas.org.in<br>> > > http://www.nascent-technologies.com<br>><br>> --<br>> KStars: http://edu.kde.org/kstars<br>> Community Forums: http://kstars.30doradus.org<br>> _______________________________________________<br>> Kstars-devel mailing list<br>> Kstars-devel@kde.org<br>> https://mail.kde.org/mailman/listinfo/kstars-devel<br>><br><br><br>-- <br>Regards,<br> Akarsh<br>http://www.bas.org.in<br>http://www.nascent-technologies.com<br><br><br>------------------------------<br><br>_______________________________________________<br>Kstars-devel mailing
list<br>Kstars-devel@kde.org<br>https://mail.kde.org/mailman/listinfo/kstars-devel<br><br><br>End of Kstars-devel Digest, Vol 47, Issue 4<br>*******************************************<br></brianhurren@yahoo.com></akarshsimha@gmail.com></jharris@30doradus.org></c00c02910706041006h7d93b9a3xaf49f0951b5a83c9@mail.gmail.com></kstars-devel@kde.org></akarshsimha@gmail.com></brianhurren@yahoo.com></akarshsimha@gmail.com></kstars-devel@kde.org></jharris@30doradus.org></blockquote><br><p> 
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