Re: Where it wil be equinox, at noon
Alex You say in your note "But in mathematics uuuf," - but this is not mathematics, it's astronomy! Nothing in the heavens moves with absolute uniformity….. If you want the very best astronomical calculations, then you must use the best technology and that is provided free by NASA-JPL. Their software is used to put spacecraft on Mars etc. and is continuously updated for changes in Delta T. You can access their software - which is called Horizons - at http://ssd.jpl.nasa.gov/horizons.cgi The people who produce the Astronomical Almanacs use JPL's routines for the positions of solar system objects Best regards Kevin Karney Freedom Cottage, Llandogo, Monmouth NP25 4TP, Wales, UK 51° 44' N 2° 41' W Zone 0 + 44 1594 530 595 --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: RE: R: Where it wil be equinox, at noon
Gian: it's likely that the difference between your result and the result in Meuus is due to (a) the complexity of the model used and (b) effects included or ignored (such as aberration, nutation, and so on). Let's remember that the average speed of the Sun in longitude is on the order of 10**(-5) degrees/second, so a difference of 3 seconds is trivial. Also, determining when the longitude is exactly 180 degrees requires some sort of approximation or interpolation, since the longitude is on the left-hand side of the relevant equations whereas time is on the right-hand side (i.e., time is an input, longitude an output). It's also worth noting that none of the models commonly used (including VSOP) is accurate to that level. Brad On Tue, Sep 27, 2011 at 2:47 AM, sun.di...@libero.it wrote: > Axel, > > from "Astronomical tables of the Sun, Moon and Planets", Jean Meeus, second > edition, page 151: Semptember equinox in 2011 is on day 23rd at 9:05:44 > (Dinamical Time). To convert to Universal Time one must subtract the value > of DeltaT. > > > Orologi Solari considers a value of DeltaT = 67.5 so that the equinox time > should be 9:04:36 (UT) while the value computed by OS is 3 seconds earlier. > I need to investigate on this (although small) difference. > > > Ciao. > > Gian > > > > Messaggio originale > Da: atg...@hotmail.com > Data: 24/09/2011 22.33 > A: , "Sundials" > Ogg: RE: R: Where it wil be equinox, at noon > > Thanks for your answers, and for you Fabio that personally wrote to my > mail, > > We all arrived at different results, but the differences are minute > in longitude and with a circumference of the earth at latitude 0 °, > (Equator) > of which is 40.075,036 kilometers, every minute of that difference is > 1.855,32 meters > for purposes of building a sundials they are not important. But in > mathematics > uuuf. > > I think each one has its source, and are different and the problem > is that we come to different results. > > James Morrison, with "Electric Astrolabe", > > 42 ° 20'59 "EAST, UT 9:10:36 > The calculated (12:00:00 -09:10:36) * 15 ° > > David Patte, with "Time Zone Master", > > 41 > ° 52'45 "EAST, UT 9:12:28 > The calculated (12:00:00 -09:12:28-1) * 15 ° ... it, -1 > > Gian, "Orologi-Solari" > > 41 > ° 59'30 "EAST, UT 9:04:33 > The calculated is (12:00:00 -09:04:33-449) * 15 449 Eot > > Me Axel, R. Cernica Sun v.5.6 42 ° 12'48 "EAST UT 9:03:42 > The calculation (12:00:00 -09:03:42-446.68) * 15 ° ... 446.68 > > where is the right thing > > My best regards for all the list > and sorry my english > Axel > 32°39'59" S > 70°42'41" W > > > > -- > Date: Sat, 24 Sep 2011 15:33:58 +0200 > From: sun.di...@libero.it > To: sundial@uni-koeln.de > Subject: R: Where it wil be equinox, at noon > > Here is my answer to Axel's question. > > With "Orologi Solari" in simulation mode, looking for the time of sun > longitude = 180 degrees, I find: > my time (TMEC + DST) = 11:04:33 that corresponds to GMT 9:04:33. > > At that time sun is on the local meridian of a place with longitude = > (12:00:00 - 9:04:33 - EoT)*15 = 41:59:30 east. > > A verification can be done by setting in OS 41:59:30 E 0:0:0 N (a place in > Somalia) and then verifying in simulation mode that at 11:04:33 (my time) > the local time is really 12:00:00. > > Ciao. > Gian > http://digilander.libero.it/orologi.solari > > Messaggio originale > Da: atg...@hotmail.com > Data: 23/09/2011 2.57 > A: > Ogg: Where it wil be equinox, at noon > > This is my Subject; > > Finding the position, Longitud, where, the sprig equinox, will ocurr at > noon, I found some diference between the results of "The Dialist´s > Companion", and "Sun v.5.6 Of R.Cernic", both programs I work for some time. > > In Longitud 42°12,80" E at 13:03:42 PM it will be Noon, for my studies > > Then I placed both programs in Latitud and longitud 0°, and in Sun v5.6 of > R.Cernic I got UT 09:03:59 AM and in The Dialist´s Companion, I found the > nearest cero declination at 08:44:47AM the altitude measure have a > difference of almost 5°, I Know The Dialist Companion I Use vers 1.1.b is > old. > > Sorry my english, it´s not my first language > > Best regards for all of you > > Axel > > 32°39'59"S > 70°42'41"W > > > > > > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > > > --- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > > --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: RE: R: Where it wil be equinox, at noon
Gian et al: I need to take back my last statement: it turns out that VSOP is accurate to about 10**(-6) degrees. Brad On Tue, Sep 27, 2011 at 5:36 AM, Brad Lufkin wrote: > Gian: > it's likely that the difference between your result and the result in Meuus > is due to (a) the complexity of the model used and (b) effects included or > ignored (such as aberration, nutation, and so on). Let's remember that the > average speed of the Sun in longitude is on the order of 10**(-5) > degrees/second, so a difference of 3 seconds is trivial. Also, determining > when the longitude is exactly 180 degrees requires some sort of > approximation or interpolation, since the longitude is on the left-hand side > of the relevant equations whereas time is on the right-hand side (i.e., time > is an input, longitude an output). It's also worth noting that none of the > models commonly used (including VSOP) is accurate to that level. > Brad > > On Tue, Sep 27, 2011 at 2:47 AM, sun.di...@libero.it > wrote: > >> Axel, >> >> from "Astronomical tables of the Sun, Moon and Planets", Jean Meeus, >> second edition, page 151: Semptember equinox in 2011 is on day 23rd at >> 9:05:44 (Dinamical Time). To convert to Universal Time one must subtract the >> value of DeltaT. >> >> >> Orologi Solari considers a value of DeltaT = 67.5 so that the equinox time >> should be 9:04:36 (UT) while the value computed by OS is 3 seconds earlier. >> I need to investigate on this (although small) difference. >> >> >> Ciao. >> >> Gian >> >> >> >> Messaggio originale >> Da: atg...@hotmail.com >> Data: 24/09/2011 22.33 >> A: , "Sundials" >> Ogg: RE: R: Where it wil be equinox, at noon >> >> Thanks for your answers, and for you Fabio that personally wrote to my >> mail, >> >> We all arrived at different results, but the differences are minute >> in longitude and with a circumference of the earth at latitude 0 °, >> (Equator) >> of which is 40.075,036 kilometers, every minute of that difference is >> 1.855,32 meters >> for purposes of building a sundials they are not important. But in >> mathematics >> uuuf. >> >> I think each one has its source, and are different and the problem >> is that we come to different results. >> >> James Morrison, with "Electric Astrolabe", >> >> 42 ° 20'59 "EAST, UT 9:10:36 >> The calculated (12:00:00 -09:10:36) * 15 ° >> >> David Patte, with "Time Zone Master", >> >> 41 >> ° 52'45 "EAST, UT 9:12:28 >> The calculated (12:00:00 -09:12:28-1) * 15 ° ... it, -1 >> >> Gian, "Orologi-Solari" >> >> 41 >> ° 59'30 "EAST, UT 9:04:33 >> The calculated is (12:00:00 -09:04:33-449) * 15 449 Eot >> >> Me Axel, R. Cernica Sun v.5.6 42 ° 12'48 "EAST UT 9:03:42 >> The calculation (12:00:00 -09:03:42-446.68) * 15 ° ... 446.68 >> >> where is the right thing >> >> My best regards for all the list >> and sorry my english >> Axel >> 32°39'59" S >> 70°42'41" W >> >> >> >> -- >> Date: Sat, 24 Sep 2011 15:33:58 +0200 >> From: sun.di...@libero.it >> To: sundial@uni-koeln.de >> Subject: R: Where it wil be equinox, at noon >> >> Here is my answer to Axel's question. >> >> With "Orologi Solari" in simulation mode, looking for the time of sun >> longitude = 180 degrees, I find: >> my time (TMEC + DST) = 11:04:33 that corresponds to GMT 9:04:33. >> >> At that time sun is on the local meridian of a place with longitude = >> (12:00:00 - 9:04:33 - EoT)*15 = 41:59:30 east. >> >> A verification can be done by setting in OS 41:59:30 E 0:0:0 N (a place in >> Somalia) and then verifying in simulation mode that at 11:04:33 (my time) >> the local time is really 12:00:00. >> >> Ciao. >> Gian >> http://digilander.libero.it/orologi.solari >> >> Messaggio originale >> Da: atg...@hotmail.com >> Data: 23/09/2011 2.57 >> A: >> Ogg: Where it wil be equinox, at noon >> >> This is my Subject; >> >> Finding the position, Longitud, where, the sprig equinox, will ocurr at >> noon, I found some diference between the results of "The Dialist´s >> Companion", and "Sun v.5.6 Of R.Cernic", both programs I work for some time. >> >> In Longitud 42°12,80" E at 13:03:42 PM it will be Noon, for my studies >> >> Then I placed both programs in Latitud and longitud 0°, and in Sun v5.6 of >> R.Cernic I got UT 09:03:59 AM and in The Dialist´s Companion, I found the >> nearest cero declination at 08:44:47AM the altitude measure have a >> difference of almost 5°, I Know The Dialist Companion I Use vers 1.1.b is >> old. >> >> Sorry my english, it´s not my first language >> >> Best regards for all of you >> >> Axel >> >> 32°39'59"S >> 70°42'41"W >> >> >> >> >> >> --- >> https://lists.uni-koeln.de/mailman/listinfo/sundial >> >> >> >> --- >> >> https://lists.uni-koeln.de/mailman/listi
Was the recent death of Richard White reported, on this List?
On trying to access the "Courtyard Sundials" website, I was saddened to see a message that Richard White has died - and that the business is therefore no longer trading. Was it previously reported, on this Mailing List, or did I miss and/or forget notification of his death? I am sure that Richard will be missed, by the Sundialling community. Does another person intend to take over his Somerset-based business? Sincerely, Anne Lennon (Mrs) --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: R: Where it wil be equinox, at noon
Just for clarity: http://aa.usno.navy.mil/data/docs/EarthSeasons.php shows the following UT values: 20112011 Perihelion Jan 3 19Equinoxes Mar 20 23 21Sept 23 09 05 AphelionJuly 4 15Solstices June 21 17 16Dec 22 05 30 ie: 9:05 UT from there you need either the RTA of the sun at that time, or you can extrapolate it using the sidereal time. -- "We don't serve your type in our bar!", exclaimed the Bartender. A faster-than-light Neutrino enters a bar. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
R: Re: RE: R: Where it wil be equinox, at noon
Brad, sun parameters are computed by OS using the VSOP87 theory as for Meeus results. Aberration and nutation are taken into account (or they should be, this is one of the points I have to check). I did not interpolate but just manually changed the simulation time in order to get 180.0 degrees for the sun longitude. Therefore I guess I really have to check my code. Of course the error is trivial, but it can / it must be removed. Ciao. Gian Messaggio originale Da: bradley.luf...@gmail.com Data: 27/09/2011 12.01 A: "sun.di...@libero.it" Cc: "Sundial Mailing List" Ogg: Re: RE: R: Where it wil be equinox, at noon Gian et al: I need to take back my last statement: it turns out that VSOP is accurate to about 10**(-6) degrees. Brad On Tue, Sep 27, 2011 at 5:36 AM, Brad Lufkin wrote: Gian: it's likely that the difference between your result and the result in Meuus is due to (a) the complexity of the model used and (b) effects included or ignored (such as aberration, nutation, and so on). Let's remember that the average speed of the Sun in longitude is on the order of 10**(-5) degrees/second, so a difference of 3 seconds is trivial. Also, determining when the longitude is exactly 180 degrees requires some sort of approximation or interpolation, since the longitude is on the left-hand side of the relevant equations whereas time is on the right-hand side (i.e., time is an input, longitude an output). It's also worth noting that none of the models commonly used (including VSOP) is accurate to that level. Brad On Tue, Sep 27, 2011 at 2:47 AM, sun.di...@libero.it wrote: Axel, from "Astronomical tables of the Sun, Moon and Planets", Jean Meeus, second edition, page 151: Semptember equinox in 2011 is on day 23rd at 9:05:44 (Dinamical Time). To convert to Universal Time one must subtract the value of DeltaT. Orologi Solari considers a value of DeltaT = 67.5 so that the equinox time should be 9:04:36 (UT) while the value computed by OS is 3 seconds earlier. I need to investigate on this (although small) difference. Ciao. Gian Messaggio originale Da: atg...@hotmail.com Data: 24/09/2011 22.33 A: , "Sundials" Ogg: RE: R: Where it wil be equinox, at noon Thanks for your answers, and for you Fabio that personally wrote to my mail, We all arrived at different results, but the differences are minute in longitude and with a circumference of the earth at latitude 0 °, (Equator) of which is 40.075,036 kilometers, every minute of that difference is 1.855,32 meters for purposes of building a sundials they are not important. But in mathematics uuuf. I think each one has its source, and are different and the problem is that we come to different results. James Morrison, with "Electric Astrolabe", 42 ° 20'59 "EAST, UT 9:10:36 The calculated (12:00:00 -09:10:36) * 15 ° David Patte, with "Time Zone Master", 41 ° 52'45 "EAST, UT 9:12:28 The calculated (12:00:00 -09:12:28-1) * 15 ° ... it, -1 Gian, "Orologi-Solari" 41 ° 59'30 "EAST, UT 9:04:33 The calculated is (12:00:00 -09:04:33-449) * 15 449 Eot Me Axel, R. Cernica Sun v.5.6 42 ° 12'48 "EAST UT 9:03:42 The calculation (12:00:00 -09:03:42-446.68) * 15 ° ... 446.68 where is the right thing My best regards for all the list and sorry my english Axel 32°39'59" S 70°42'41" W Date: Sat, 24 Sep 2011 15:33:58 +0200 From: sun.di...@libero.it To: sundial@uni-koeln.de Subject: R: Where it wil be equinox, at noon Here is my answer to Axel's question. With "Orologi Solari" in simulation mode, looking for the time of sun longitude = 180 degrees, I find: my time (TMEC + DST) = 11:04:33 that corresponds to GMT 9:04:33. At that time sun is on the local meridian of a place with longitude = (12:00:00 - 9:04:33 - EoT)*15 = 41:59:30 east. A verification can be done by setting in OS 41:59:30 E 0:0:0 N (a place in Somalia) and then verifying in simulation mode that at 11:04:33 (my time) the local time is really 12:00:00. Ciao. Gian http://digilander.libero.it/orologi.solari Messaggio originale Da: atg...@hotmail.com Data: 23/09/2011 2.57 A: Ogg: Where it wil be equinox, at noon This is my Subject; Finding the position, Longitud, where, the sprig equinox, will ocurr at noon, I found some diference between the results of "The Dialist´s Companion", and "Sun v.5.6 Of R.Cernic", both programs I work for some time. In Longitud 42°12,80" E at 13:03:42 PM it will be Noon, for my studies Then I placed both programs in Latitud and longitud 0°, and in Sun v5.6 of R.Cernic I got UT 09:03:59 AM and in The Dialist´s Companion, I found the nearest cero declination at 08:44:47AM the altitude measure have a difference of almost 5°, I
Re: Re: RE: R: Where it wil be equinox, at noon
Gian: I calculated the longitude using VSOP87D and all the corrections mentioned in Meuus's Astro Algorithms and, if it makes you feel any better, my result agrees with yours (i.e., the Sun's longitude is closest to 180 degrees at 9:05:41 DT). Brad On Tue, Sep 27, 2011 at 2:22 PM, sun.di...@libero.it wrote: > Brad, > > sun parameters are computed by OS using the VSOP87 theory as for Meeus > results. > > Aberration and nutation are taken into account (or they should be, this is > one of the points I have to check). > > I did not interpolate but just manually changed the simulation time in > order to get 180.0 degrees for the sun longitude. > > Therefore I guess I really have to check my code. > > Of course the error is trivial, but it can / it must be removed. > > Ciao. > > Gian > > Messaggio originale > Da: bradley.luf...@gmail.com > Data: 27/09/2011 12.01 > A: "sun.di...@libero.it" > Cc: "Sundial Mailing List" > Ogg: Re: RE: R: Where it wil be equinox, at noon > > Gian et al: > I need to take back my last statement: it turns out that VSOP is accurate > to about 10**(-6) degrees. > Brad > > On Tue, Sep 27, 2011 at 5:36 AM, Brad Lufkin wrote: > >> Gian: >> it's likely that the difference between your result and the result in >> Meuus is due to (a) the complexity of the model used and (b) effects >> included or ignored (such as aberration, nutation, and so on). Let's >> remember that the average speed of the Sun in longitude is on the order of >> 10**(-5) degrees/second, so a difference of 3 seconds is trivial. Also, >> determining when the longitude is exactly 180 degrees requires some sort of >> approximation or interpolation, since the longitude is on the left-hand side >> of the relevant equations whereas time is on the right-hand side (i.e., time >> is an input, longitude an output). It's also worth noting that none of the >> models commonly used (including VSOP) is accurate to that level. >> Brad >> >> On Tue, Sep 27, 2011 at 2:47 AM, sun.di...@libero.it < >> sun.di...@libero.it> wrote: >> >>> Axel, >>> >>> from "Astronomical tables of the Sun, Moon and Planets", Jean Meeus, >>> second edition, page 151: Semptember equinox in 2011 is on day 23rd at >>> 9:05:44 (Dinamical Time). To convert to Universal Time one must subtract the >>> value of DeltaT. >>> >>> >>> Orologi Solari considers a value of DeltaT = 67.5 so that the equinox >>> time should be 9:04:36 (UT) while the value computed by OS is 3 seconds >>> earlier. I need to investigate on this (although small) difference. >>> >>> >>> Ciao. >>> >>> Gian >>> >>> >>> >>> Messaggio originale >>> Da: atg...@hotmail.com >>> Data: 24/09/2011 22.33 >>> A: , "Sundials" >>> Ogg: RE: R: Where it wil be equinox, at noon >>> >>> Thanks for your answers, and for you Fabio that personally wrote to my >>> mail, >>> >>> We all arrived at different results, but the differences are minute >>> in longitude and with a circumference of the earth at latitude 0 °, >>> (Equator) >>> of which is 40.075,036 kilometers, every minute of that difference is >>> 1.855,32 meters >>> for purposes of building a sundials they are not important. But in >>> mathematics >>> uuuf. >>> >>> I think each one has its source, and are different and the problem >>> is that we come to different results. >>> >>> James Morrison, with "Electric Astrolabe", >>> >>> 42 ° 20'59 "EAST, UT 9:10:36 >>> The calculated (12:00:00 -09:10:36) * 15 ° >>> >>> David Patte, with "Time Zone Master", >>> >>> 41 >>> ° 52'45 "EAST, UT 9:12:28 >>> The calculated (12:00:00 -09:12:28-1) * 15 ° ... it, -1 >>> >>> Gian, "Orologi-Solari" >>> >>> 41 >>> ° 59'30 "EAST, UT 9:04:33 >>> The calculated is (12:00:00 -09:04:33-449) * 15 449 Eot >>> >>> Me Axel, R. Cernica Sun v.5.6 42 ° 12'48 "EAST UT 9:03:42 >>> The calculation (12:00:00 -09:03:42-446.68) * 15 ° ... 446.68 >>> >>> where is the right thing >>> >>> My best regards for all the list >>> and sorry my english >>> Axel >>> 32°39'59" S >>> 70°42'41" W >>> >>> >>> >>> -- >>> Date: Sat, 24 Sep 2011 15:33:58 +0200 >>> From: sun.di...@libero.it >>> To: sundial@uni-koeln.de >>> Subject: R: Where it wil be equinox, at noon >>> >>> Here is my answer to Axel's question. >>> >>> With "Orologi Solari" in simulation mode, looking for the time of sun >>> longitude = 180 degrees, I find: >>> my time (TMEC + DST) = 11:04:33 that corresponds to GMT 9:04:33. >>> >>> At that time sun is on the local meridian of a place with longitude = >>> (12:00:00 - 9:04:33 - EoT)*15 = 41:59:30 east. >>> >>> A verification can be done by setting in OS 41:59:30 E 0:0:0 N (a place >>> in Somalia) and then verifying in simulation mode that at 11:04:33 (my time) >>> the local time is really 12:00:00. >>> >>> Ciao. >>> Gian >>> http://digilander.libero.it/orologi.solari >>> >
