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Shouldn't be this defined in Terrestrial Time?
Yes, so why not change it now? Nike 06:53, 17 Dec 2004 (UTC)
Is it known how long the current epoch will be adhered to? Do we know what will come next? Are these questions relevant; and if not, why not? Can this be clarified in the article? (As may be apparent, I don't have a clue.) -- Cimon avaro; on a pogostick. 11:58, 14 January 2006 (UTC)
Should there be a reference to Epoch/Unix time here - 1453330082 66.194.64.130 ( talk) 22:48, 20 January 2016 (UTC)
What's with all the #s? I've never seen this usage anywhere. #Julian epoch is just bizarre. Also, why are there links to articles which no longer exist?
Although the article only mentions one Julian epoch, I have also seen J1900 and J1950. -- Nike 08:51, 3 August 2006 (UTC)
I get it, those are supposed to be links to sections within the article. You need to use a piped link. That would look like this: [[#J2000.0|J2000.0]] -- Nike 09:00, 3 August 2006 (UTC)
What are Besselian vs. Julian epochs? How do they differ from each other aside from what letter is prefixed to their number? -- Haruo 10:03, 6 October 2006 (UTC)
What about the article is unclear in explaining this? -- Nike 11:38, 6 October 2006 (UTC)
What I want to know is why the phrase "Since the right ascension and declination of stars are constantly changing due to precession..." is repeated verbatim in every section. BIEB!! 13:07, 25 October 2006 (UTC)
This page may be mis-titled completely. When speaking of terms such as 'B1950.0' and 'J2000.0', especially in the context of celestial coordinates and precession, you are speaking of EQUINOX, not EPOCH. For example, the EPOCH of observation on a star may be 1991.25, but the coordinates given for its posistion may be specified in EQUINOX J2000.0 (The Hipparcos and Tycho stellar catalogs are a good example of this). Radec 08:15, 21 January 2007 (UTC)
I was directed to Epoch by the Comet Infobox on the Comet McNaught article, which states "Epoch: 2454113.2961 (January 20, 2007)". It was not immediately apparent from this article that the stated epoch was in fact a Julian Day, and that I should refer to that article for an explanation of the number 2454113.2691. If a subject expert is revising this article, it would be helpful if they would consider this usage. PaulKishimoto 17:57, 21 January 2007 (UTC)
I believe this is a problem with the Comet Infobox and not this page. Icez 02:15, 5 February 2007 (UTC)
The article states
Does that imply according to the Julian calendar? —Preceding unsigned comment added by Trigamma ( talk • contribs) 22:58, 4 January 2008 (UTC)
We need more info about B1875. 65.94.47.63 ( talk) 08:54, 2 July 2011 (UTC)
Why is noon/midday written as 12h rather than 12:00 as in ISO 8601? – Kaihsu ( talk) 05:58, 23 April 2014 (UTC)
Since the date format in the article is not consistent, I will follow MOS:DATEVAR and use the format used when a date was first added to the article, which is month, day, year. Jc3s5h ( talk) 14:28, 6 August 2018 (UTC)
I agree the format for dates is inconsistent. However, being an article about astronomy, there is an internationally recognized standard for epochs mandated by the International Astronomical Union (see for example https://www.iau.org/static/publications/stylemanual1989.pdf, page S29) that shall be followed. Marco.bs ( talk) 10:54, 7 August 2018 (UTC)
I assume the following is a typo? 1950?
"Julian years, e.g., J2000.0 for January 1.5, 1950, TT"
Also, dates in the form "January 0.9235, 1950 TT" are beyond me. I consulted TT (terrestrial time) to learn what that phrase means and find no examples or templates there to explain such a date. "Julian Day" explains its own use of fractional days, but I haven't found anything to confirm any of my guesses as to how to specify such a day with a month.
74.79.156.16 ( talk) 20:05, 1 October 2018 (UTC)
January 0.9235, 1950 TT = December 31.9235, 1949 TT = December 31, 1949 22:09:50.4 TT. (Historically, the "January 0" concept arose because astronomers start the day 12 hours before non-astronomers do. Astronomers didn't want the year number to decrement "unnecessarily".)
![]() | This ![]() It is of interest to the following WikiProjects: | ||||||||||||||||||||
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Shouldn't be this defined in Terrestrial Time?
Yes, so why not change it now? Nike 06:53, 17 Dec 2004 (UTC)
Is it known how long the current epoch will be adhered to? Do we know what will come next? Are these questions relevant; and if not, why not? Can this be clarified in the article? (As may be apparent, I don't have a clue.) -- Cimon avaro; on a pogostick. 11:58, 14 January 2006 (UTC)
Should there be a reference to Epoch/Unix time here - 1453330082 66.194.64.130 ( talk) 22:48, 20 January 2016 (UTC)
What's with all the #s? I've never seen this usage anywhere. #Julian epoch is just bizarre. Also, why are there links to articles which no longer exist?
Although the article only mentions one Julian epoch, I have also seen J1900 and J1950. -- Nike 08:51, 3 August 2006 (UTC)
I get it, those are supposed to be links to sections within the article. You need to use a piped link. That would look like this: [[#J2000.0|J2000.0]] -- Nike 09:00, 3 August 2006 (UTC)
What are Besselian vs. Julian epochs? How do they differ from each other aside from what letter is prefixed to their number? -- Haruo 10:03, 6 October 2006 (UTC)
What about the article is unclear in explaining this? -- Nike 11:38, 6 October 2006 (UTC)
What I want to know is why the phrase "Since the right ascension and declination of stars are constantly changing due to precession..." is repeated verbatim in every section. BIEB!! 13:07, 25 October 2006 (UTC)
This page may be mis-titled completely. When speaking of terms such as 'B1950.0' and 'J2000.0', especially in the context of celestial coordinates and precession, you are speaking of EQUINOX, not EPOCH. For example, the EPOCH of observation on a star may be 1991.25, but the coordinates given for its posistion may be specified in EQUINOX J2000.0 (The Hipparcos and Tycho stellar catalogs are a good example of this). Radec 08:15, 21 January 2007 (UTC)
I was directed to Epoch by the Comet Infobox on the Comet McNaught article, which states "Epoch: 2454113.2961 (January 20, 2007)". It was not immediately apparent from this article that the stated epoch was in fact a Julian Day, and that I should refer to that article for an explanation of the number 2454113.2691. If a subject expert is revising this article, it would be helpful if they would consider this usage. PaulKishimoto 17:57, 21 January 2007 (UTC)
I believe this is a problem with the Comet Infobox and not this page. Icez 02:15, 5 February 2007 (UTC)
The article states
Does that imply according to the Julian calendar? —Preceding unsigned comment added by Trigamma ( talk • contribs) 22:58, 4 January 2008 (UTC)
We need more info about B1875. 65.94.47.63 ( talk) 08:54, 2 July 2011 (UTC)
Why is noon/midday written as 12h rather than 12:00 as in ISO 8601? – Kaihsu ( talk) 05:58, 23 April 2014 (UTC)
Since the date format in the article is not consistent, I will follow MOS:DATEVAR and use the format used when a date was first added to the article, which is month, day, year. Jc3s5h ( talk) 14:28, 6 August 2018 (UTC)
I agree the format for dates is inconsistent. However, being an article about astronomy, there is an internationally recognized standard for epochs mandated by the International Astronomical Union (see for example https://www.iau.org/static/publications/stylemanual1989.pdf, page S29) that shall be followed. Marco.bs ( talk) 10:54, 7 August 2018 (UTC)
I assume the following is a typo? 1950?
"Julian years, e.g., J2000.0 for January 1.5, 1950, TT"
Also, dates in the form "January 0.9235, 1950 TT" are beyond me. I consulted TT (terrestrial time) to learn what that phrase means and find no examples or templates there to explain such a date. "Julian Day" explains its own use of fractional days, but I haven't found anything to confirm any of my guesses as to how to specify such a day with a month.
74.79.156.16 ( talk) 20:05, 1 October 2018 (UTC)
January 0.9235, 1950 TT = December 31.9235, 1949 TT = December 31, 1949 22:09:50.4 TT. (Historically, the "January 0" concept arose because astronomers start the day 12 hours before non-astronomers do. Astronomers didn't want the year number to decrement "unnecessarily".)