Solar culmination and equation of time Calculator

Calculates a table of changes in the solar culmination and equation of time for a year and draws the chart.

Input negative degree for west longtitude.
Daylight Saving time is not taken into consideration.

Solar culmination and equation of time
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    2. [ Calculation interval
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    2. Time zone
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    4. (9:Japan)

・The factors which equation of time produces are the Earth's orbital eccentricity and axial tilt.
・equation of time = mean solar time − apparent solar time
     =(time zone - longitude/15)+12h− solar culmination
・If the longitude of the standard time is specified, the mean solar time will become noon.

Solar culmination and equation of time
[1-10] /30Disp-Num
[1]  2018/11/19 21:23   Male / 60 years old level or over / A retired person / Very /
Purpose of use
Will be useful for helping people determine true north with only a watch and a noontime shadow.
Thank you very much for making this great tool available; quite marvelous!

Previous poster might wish to check out MICA, the Multiyear Interactive Computer Almanac for comparisons; - this is the tool I've used in the past to create my own ET tables and other data tables for surveying programs.

[2]  2018/11/17 05:14   Male / 30 years old level / High-school/ University/ Grad student / A little /
Purpose of use
To verify equation of time matches my own calculations as an amateur astronomer.
Questionable accuracy?! Im not saying my calculations are more accurate - they are probably worse. I just have no way of verifying your own results. You provide no relevant external links, equations, or discussion on methods. I cannot verify or falsify any of this except to gather equally baseless numbers from a multitude of sites, none of which are ever consistent with one another.
[3]  2018/09/14 21:05   Male / 60 years old level or over / A retired person / Useful /
Purpose of use
looking for formula.
[4]  2018/08/10 04:52   Male / 60 years old level or over / An engineer / Useful /
Purpose of use
Test case for an embedded Eqn of Time calculation
[5]  2018/08/06 02:49   Male / 60 years old level or over / An engineer / Very /
Purpose of use
Correction of sunrise times observed on VLF radio waves propagation along a whole year.
[6]  2018/03/23 18:58   Male / 60 years old level or over / A retired people / Useful /
Purpose of use
A study on the times of the five daily Muslim prayers.
I am wondering if the times of solar culmination are the same as solar meridian crossing. In Islam, the prayer time for Dhuhr (noon prayer) is after the sun has passed its highest elevation, or istiwa.

Please clarify if the highest elevation of the sun for the day is culmination or meridian crossing.
[7]  2018/03/11 05:30   Female / Under 20 years old / Elementary school/ Junior high-school student / Very /
Purpose of use
Planning sundial observations.
Thanks - really helpful!
[8]  2018/01/17 04:48   Male / 60 years old level or over / An engineer / Very /
Purpose of use
Someone asserted that December 24th was the "longest day of the year." He was unable to clarify further. The standard explanation for the longest day of the year is most hours of sunlight. An alternative definition is least time between transits (culmination) of the apparent sun. This is simply the time difference between successive transits, which turns out to be smallest - 21.48 seconds less than 24 hours- by the precision offered, between the transits of September 17 and 18, and longest, 29.82 seconds longer than 24 hours, between the transits of December 22 and 23. So by this definition, one might consider December 23 to be the longest day of the year.
Thank you so much!
[9]  2017/06/26 14:41   Male / 60 years old level or over / A retired people / Very /
Purpose of use
To orient a sun dial at true noon and to obtain the relevant equation of time for my longitude
Excellent resource
[10]  2017/04/10 14:34   Male / 50 years old level / A teacher / A researcher / Useful /
Purpose of use
To illustrate WHY the Islamic prayer times vary across the year as they do.


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