Altri ALGORITMI + errata corrige
Alessandro Palladino
Mi fa piacere che l'argomento interessi qualcuno, pero' devo
avvisarvi che c'era un piccolo errore nel messaggio precedente. In
effetti il 2000 e' bisestile quindi c'e' un giorno in piu'. Vi
riposto l'algoritmo corretto e per farmi perdonare anche quello per
angolo orario e declinazione del sole, cosi' veramente fate tutto con
la calcolatrice! Pero' attenzione che gli ultimi due non li ho
ancora provati e potrebbero contenere degli errori. Ah! a proposito,
se non vi trovate con la traduzione delle sigle astronomiche guardate
a pag 2 delle effemeridi italiane.
buon vento a tutti
Alessandro Palladino <pal...@usa.net>
**********************************************************
Step 1 Working with the Greenwich time and date, calculate the number
of centuries before (-) or after (+) 1200 1 Jan 2000.
Year Month
1997 -94,737,600 Jan 0 Jul 15,638,400
1998 -63,201,600 Feb 2,678,400 Aug 18,316,800
1999 -31,665,600 Mar 5,097,600 Sep 20,995,200
2000 -129,600 Apr 7,776,000 Oct 23,587,200
2001 31,579,200 May 10,368,000 Nov 26,265,600
2002 63,115,200 Jun 13,046,400 Dec 28,857,600
2003 94,651,200
Number for the year ___,___,___ year ____
Number for the month __,___,___ month ____
Day ___ x 86,400 = _,___,___
Hour ___ x 3,600 = __,___
Minute ___ x 60 = _,___
Second ___ __
__,___per date da Marzo 2000 in poi
aggiungere 86,400
Total seconds ___,___,___ / 3,155,760,000 =
Centuries __.___ ___ ___ ___ = T
Step 2 Calculate the GHA of Aries, GHAA, in revolutions. Remove the
integer part of the number leaving the decimal part. It can be either
positive or negative. If it is negative, add 1 to it to make it
positive. Multiply the revolutions by 360 to convert it to decimal
degrees and if desired to degrees and minutes.
GHAA = 0.7790573 + 36,625.0021390T + 0.0000011T^2
- 0.0000122sin(125.0 - 1934.1T) - 0.0000009sin(200.9 +
72,001.7T) =
____._______ rev.
_0._______ rev (decimal part)
0._______ rev (if negative, decimal part + 1)
___.____ ° ___ ° __._ '
Step 3 Calculate the Sun's mean anomaly.
g = 357.528 + 35,999.051T
____.____°
Step 4 Calculate the ecliptic longitude of the Sun.
EL = 280.466 + 36,000.771T + 1.915sin(g) + 0.020sin(2g)
____.____°
Step 5 Calculate the obliquity of the ecliptic.
e = 23.440 + 0.015T
__.____°
Step 6 Check to see if cos(EL) is positive _ or negative _.
Calculate the GHA Sun. Add 180° to the value if the cosine of EL is
negative. Add or subtract multiples of 360° until the answer is
between 0 and 360°
GHA Sun = GHAA - tan-1(cos(e)tan(EL)) (+ 180° if cos(EL) is negative)
___.____° ___ ° __._ '
Step 7 Calculate the Declination of the Sun. Negative values are
south; positive are north.
Dec Sun = sin-1(sin(e)sin(EL))
___.____° _ __ ° __._ '
****************** ESEMPIO *******************************
Step 1 Working with the Greenwich time and date, calculate the number
of centuries before (-) or after (+) 1200 1 Jan 2000.
Year Month
1997 -94,737,600 Jan 0 Jul 15,638,400
1998 -63,201,600 Feb 2,678,400 Aug 18,316,800
1999 -31,665,600 Mar 5,097,600 Sep 20,995,200
2000 -129,600 Apr 7,776,000 Oct 23,587,200
2001 31,579,200 May 10,368,000 Nov 26,265,600
2002 63,115,200 Jun 13,046,400 Dec 28,857,600
2003 94,651,200
Number for the year -94,737,600 year 1997
Number for the month 28,857,600 month Dec
Day ___ x 86,400 = _,864,000
Hour ___ x 3,600 = 28,800
Minute ___ x 60 = _,___
Second ___ __
__,___per date da Marzo 2000 in poi
aggiungere 86,400
Total seconds -64,987,200 / 3,155,760,000 =
Centuries -0.020 593 201 = T
Step 2 Calculate the GHA of Aries, GHAA, in revolutions. Remove the
integer part of the number leaving the decimal part. It can be either
positive or negative. If it is negative, add 1 to it to make it
positive. Multiply the revolutions by 360 to convert it to decimal
degrees and if desired to degrees and minutes.
GHAA = 0.7790573 + 36,625.0021390T + 0.0000011T^2
- 0.0000122sin(125.0 - 1934.1T) - 0.0000009sin(200.9 +
72,001.7T) =
-753.4469769 rev.
-0.4469769 rev (decimal part)
0.5530231 rev (if negative, decimal part + 1)
199.0883 ° 199 ° 05.3 '
Step 3 Calculate the Sun's mean anomaly.
g = 357.528 + 35,999.051T
-383.8077°
Step 4 Calculate the ecliptic longitude of the Sun.
EL = 280.466 + 36,000.771T + 1.915sin(g) + 0.020sin(2g)
_461.6929°
Step 5 Calculate the obliquity of the ecliptic.
e = 23.440 + 0.015T
23.4397°
Step 6 Check to see if cos(EL) is positive _ or negative _.
Calculate the GHA Sun. Add 180° to the value if the cosine of EL is
negative. Add or subtract multiples of 360° until the answer is
between 0 and 360°
GHA Sun = GHAA - tan-1(cos(e)tan(EL)) (+ 180° if cos(EL) is negative)
301.8001° 301 ° 48.0 '
Step 7 Calculate the Declination of the Sun. Negative values are
south; positive are north.
Dec Sun = sin-1(sin(e)sin(EL))
-22.9252° S 22 ° 55.5 '
--
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Alx
Alessandro Palladino ha scritto:
...........il 2000 e' bisestile quindi c'e' un giorno in piu'.Grazie per aver messo a disposizione il tuo metodo. Quando mi deciderò ad imparare ad usare il sestante (spero presto) lo studierò. Però, che io sappia, il 2000, come tutti gli anni divisibili per 400, non è bisestile.
Alessandro Palladino <pal...@usa.net>
Con questo messaggio spero di non aver creato guai informatici (so usare il computer quasi come il sestante).
Buon vento.