Seâdet-i Ebediyye Endless Bliss Fourth Fascicle by Huseyin Hilmi Isik - HTML preview

Appendix IV

TABLE EQUATION OF TIME and DECLINATION OF THE SUN (1986 *)

00:00 in Universal Time (UT, GMT)

(Continued)

E: equation of time, S: declination of the Sun, min: minutes, sec: seconds.

These values are for solar years 1986+4n (n=0,1,2,3,...). For 1987+4n, values corresponding to 6 hours earlier; for 1988+4n, values corresponding to 12 hours earlier (prior to March) and to 12 hours later (from March on); for 1989+4n, values corresponding to 6 hours later are used. For example, for 0 Jan. 1989 (31 Dec. 1988) the declination is determined as follows;

Declination (S) = –23^o27' - [-23^o27' - (-23^o03')] x 6÷24= -23^o06'. Ibrâhîm Fezârî Baghdâdî was the earliest Muslim to devise the quadrant and use it to measure the Sun’s altitude. Among the very valuable books that he wrote are Zeyj-i-Fezârî, Amal-i-bi-l-usturlâb, and Kitâb-ul-mikyâs-uz-zawâl. He passed away in 188 [A.D. 803]. Two other extremely valuable books are Kitâb-ulusturlâb, by Usbu’ Ghirnâtî (of Granada), who passed away in 426 (hijrî), and Ridâyat-ul-mubtadî, by Alî bin Ahmad Baghdâdî (of Baghdâd) who passed away in 801 [A.D. 1398] in Egypt.

Appendix IV (Continued)

E = (true time)-(mean time).

The above values are determined when it was 00.00 in London at midnights. They are used after correction in direct proportion to the relevant longitude, and time. for a given time t in standard time is calculated from S = S2 + (S2 - S1) x (t-(S/15))/24 whereS1 and S2 are the values on that day and on the following, respectively; S is the degree of the meridian determining standard time; all used with their algebraic signs.