Template talk:Zodiac date

Cusp date
Would it be possible to expand this template, or create a new one, to allow the possibility of generating just one date (the cusp date)? There is an article Cusp (astrology) which is currently a dog's breakfast in several respects. Not least that article is problematic because it makes the idea of "cusp" birthdays being somehow distinct from other birthdays sound astrologically legitimate, which it really isn't. But quite apart from that, the cusp article suffers from the same problem that Zodiac used to: people incessantly edit the dates to their idea of "correct," which because of the nature of the article's subject matter usually means eternally expanding the range of dates for each cusp. My thought was to edit in calls to the "zodiac date" template, so there'd be just one date for every cusp (preferably, the correct date), and then make it clearer in the article text that some people think the cusp has a broader influence but it's by definition not meaningful to give precise starting and ending dates. The problem: the current zodiac-date template is designed to only ever return two dates at a time. It'd be nice to have a template to call, or an option on this template or something, to return just one date. 128.100.5.116 (talk) 15:17, 16 June 2009 (UTC)

This template don't work properly. It gives the wrong dates according to the Ephemeris. --78.69.85.108 (talk) 20:52, 20 July 2009 (UTC)

The template should indeed be improved. I hacked it together last April to get rid of the worst of people incessantly edit the dates to their idea of "correct", but it should certainly be refined. Ideally by somebody who actually cares about astrology and at the same time has sufficient understanding of the math involved, I am not sure if this is too much to ask, but I declare that I have no intention to spend much effort in further fine-tuning this template. The accuracy of the calculation can be improved indefinitely by adding further sine terms to the series. At present there is only one term, crudely rooted in the data of 2009, and I imagine the accuracy will decline the further away we move from 2009. The figures should either be re-calibrated for the current year, or the expansion series should be improved so that the calculation is accurate at least for the next couple of decades. --dab (𒁳) 10:19, 15 January 2010 (UTC)

No original research
The Wikipedia policy "No original research" requires that information appearing articles, except common knowledge, be cited to reliable sources. This could in principle be done either in the template itself, or in the articles in which the template is transcluded. But the template does not give any citations, and at least the "Zodiac" article does not. At Talk:Zodiac Dbachmann wrote "If the template isn't accurate enough for you, either stop using it or improve it. Don't delete a template doing astronomical calculations because it doesn't have 100% accuracy." It isn't up to a reader to find appropriate references to see if the calculations are correct; it is up to the person adding content to the encyclopedia to cite sources that show the content is correct.

Since the template currently has no explanation of how to use it, much less how it works, a reader is in no position to know where to look to see if it is correct. Another editor is in no position to try different parameter values to compare to tabulated values that are available in various places.

The "No original research policy" has a section, "WP:NOR. The calculations in the template seem like much more than "Basic arithmetic, such as adding numbers, converting units, or calculating a person's age". I suppose the calculation would be acceptable as a compact way of summarizing a reliable source, provided the source it was compared against, and the date range for which it was compared, was stated. Jc3s5h (talk) 13:08, 5 September 2012 (UTC)
 * I fully agree. Templates are never explicitly exempted from sourcing requirements, and as the information appears in articles it needs to be sourced. As with any other content, the editor who inserts the information is required to provide references if asked for (and it is clear Jc3s5h ask for such sources) or the non-sourced information maybe removed (I would suggest to only remove the content after a reasonable time to add the reference has passed to avoid edit war). Arnoutf (talk) 17:17, 5 September 2012 (UTC)


 * I have added an accuracy section, containing a citation, to Zodiac date. Jc3s5h (talk) 00:19, 7 September 2012 (UTC)

About the template "Template:Zodiac date IAU"
About the template "Template:Zodiac date IAU":

1. 25.5 + 38.2 + 29.3 + 21.1 + 36.9 + 44.5 + 21.1 + 8.4 + 18.4 + 33.6 + 27.4 + 23.9 + 37.7 = 366.0

Why isn't it 365.2425?

2. What's the meaning of constant value 365.25636?

Why isn't it 365.2425 + 365.2425 / 25772 ≈ 365.256672?

3. Are the following results of the template calls all correct?

2005: 18 April – 14 May

2006: 18 April – 14 May

2007: 19 April – 14 May

2008: 18 April – 13 May

2009: 18 April – 14 May

2010: 19 April – 14 May

2011: 19 April – 14 May

2012: 18 April – 14 May

--Regards, 124.64.216.170 (talk) 18:30, 5 September 2012 (UTC)


 * Q: What's the meaning of constant value 365.25636?
 * A: According to the Astronomical Almanac for the Year 2011, for the year 2011.0, the length of the sidereal year is 365.256363 days. The other year lengths are not especially close; the closest is the anomalistic year, which is 365.259636 days. Jc3s5h (talk) 19:01, 5 September 2012 (UTC)

I calculated my own table of dates, by finding the astrometric geocentric position of the Sun using the Multi-year Computer Interactive Almanac from the US Naval Observatory. I then used the Standards of Fundamental Astronomy software library, as modified by me to work with the Microsoft C++ compiler, to precess the position to 1875, which is when the constellation boundaries were defined. Then I rewrote software described by Nancy Roman in her July 1987 paper "Identification of a Constellation from a Position" in Publications of the Astronomical Society of the Pacific and available in the Astrophysics Data System and used it to look up what constellation the Sun was in. Times are UT1. Results:

Jc3s5h (talk) 02:14, 6 September 2012 (UTC)

Q: 25.5 + 38.2 + 29.3 + 21.1 + 36.9 + 44.5 + 21.1 + 8.4 + 18.4 + 33.6 + 27.4 + 23.9 + 37.7 = 366.0

Why isn't it 365.2425?

A: Although this summation is present in the documentation, the source code does not include the last addend, "37.7".

The principle of operation of this template seems to be to start at the date when the Sun moves from Pisces to Aries in 2009, which is taken to be 18:00 April 18 (implicitly, UT1). I believe it is actually between 16:00 and 17:00 UT1. A template is called to get the Julian date for that date, then the number of days in a sidereal year is added for each year after 2009. Then the number of days the Sun spends in each constellation is added until the constellation specified by the input parameter is reached. I have not examined the accuracy of the claimed durations, nor have I examined how much they change from year to year. Finding when the Sun will return to the same longitude by adding sidereal years seems accurate enough for this application. Jc3s5h (talk) 13:08, 7 September 2012 (UTC)

Accuracy requirement
Before trying to access or improve the accuracy of this template, I think it makes sense to figure out what the requirement is. I doubt there is a need to provide an accurate current-year list of dates for these reasons:


 * As far as I can tell, no astrologers concern themselves with which IAU constellation the sun is in.
 * Astronomers have no interest in which constellation the Sun is in; for automated telescopic observation of the Sun a better measurement system is required, and for naked eye observation, you can't see the stars anyway.

I think the requirement for understanding which IAU constellation the Sun is in would come from readers who have observed the similar terminology between astrologers and astronomers, and are trying to understand, conceptually, the similarities and differences between astrological and astronomical terminology. For this purpose, a table that is accurate for a single stated year would suffice.

There is a requirement that whatever dates are given be correct and supported by a reliable source. If they are incorrect, a few readers will waste time trying to figure out which source to believe. If not cited to a reliable source, the article will be like most of the astrological web sites out there. Jc3s5h (talk) 13:31, 7 September 2012 (UTC)

Reliable source
Here is a reliable source for the dates the Sun is in each constellation:

http://spaceplace.nasa.gov/starfinder3/

Perhaps the template should be modified to reflect this information. That is, emit one fixed set of dates and don't even try to adjust to the current year. Most readers are probably interested in the concept rather than a particular year. For those readers that are interested in a particular year, we don't know which one they want. It's better to give information ± 1 day that the reader will believe because of the source than information that is correct for a given year but not credible because there is no citation. Jc3s5h (talk) 15:46, 7 September 2012 (UTC)

Verified template bugs
The template is coded as follows:



–



About the following dates (Results of the template calls): 2012:

January 21  6: 18: 19  –  February 17   15: 54: 19

February 17  15: 54: 19  –  March 12   13: 30: 19

March 12  13: 30: 19  –  April 19   6: 18: 19 // The following date is April 18   12: 27: 28

April 18  12: 27: 28  –  May 14   0: 27: 28 // The previous date is April 19   6: 18: 19

May 14  0: 27: 28  –  June 21   5: 15: 28

June 21  5: 15: 28  –  July 20   12: 27: 28

July 20  12: 27: 28  –  August 10   14: 51: 28

August 10  14: 51: 28  –  September 16   12: 27: 28

September 16  12: 27: 28  –  October 31   0: 27: 28

October 31  0: 27: 28  –  November 21   2: 51: 28

November 21  2: 51: 28  –  November 29   12: 27: 28

November 29  12: 27: 28  –  December 17   22: 3: 28

December 17  22: 3: 28  –  January 20   12: 27: 28

2013:

January 20  12: 27: 28  –  February 16   22: 3: 28

February 16  22: 3: 28  –  March 12   19: 39: 28

March 12  19: 39: 28  –  April 19   12: 27: 28 // The following date is April 18   18: 36: 38

April 18  18: 36: 38  –  May 14   6: 36: 38 // The previous date is April 19   12: 27: 28

May 14  6: 36: 38  –  June 21   11: 24: 38

June 21  11: 24: 38  –  July 20   18: 36: 38

July 20  18: 36: 38  –  August 10   21: 0: 38

August 10  21: 0: 38  –  September 16   18: 36: 38

September 16  18: 36: 38  –  October 31   6: 36: 38

October 31  6: 36: 38  –  November 21   9: 0: 38

November 21  9: 0: 38  –  November 29   18: 36: 38

November 29  18: 36: 38  –  December 18   4: 12: 38

December 18  4: 12: 38  –  January 20   18: 36: 38 From April 19 to April 18? Why?

Regards, --124.64.223.131 (talk) 21:33, 15 September 2012 (UTC)

Replaced template
I have replaced the template so it matches the dates given at the NASA website that I described in the section. Jc3s5h (talk) 12:40, 16 September 2012 (UTC)

Verified error in Template:Zodiac date
The template claims the Sun enters the Pisces astrological sign on 19 February 2015 (UTC) but in reality it enters the sign between 2015 Feb 18 23:49:00 and 2015 Feb 18 23:50:00 UT1, according to the (US) Naval Observatory's software Multi Year Computer Almanac v. 2.2.2. Jc3s5h (talk) 21:46, 22 November 2015 (UTC)