HP Prime and Casio fx-9860GII/Prizm: Angular Distance Between Stars
Given the right
ascension (α) and declination (δ) of two stars of the same epoch (J2000.0 is
the most current), the distance between the stars are:
d = acos( sin δ1
* sin δ2 + cos δ1 * cos δ2 * cos (α1 – α2) )
The distance is
usually given in decimal degrees.
Enter α in
terms of hours, minutes, seconds (standard notation) and δ in terms of degrees,
minutes, seconds (standard notation).
HP Prime Program: ANGSTAR
EXPORT ANGSTAR(α1,δ1,α2,δ2)
BEGIN
// 2017-06-08 EWS
// Angular Angle
// Degrees
HAngle:=1;
LOCAL d;
α1:=15*α1;
α2:=15*α2;
d:=ACOS(SIN(δ1)*SIN(δ2)+
COS(δ1)*COS(δ2)*COS(α1-α2));
RETURN →HMS(d);
END;
Casio fx-9860GII/Prizm Program:
ANGSTAR
Deg
“RA 1: “?→A
“DEC1: “?→B
15A→A
“RA 2: “?→C
“DEC2: “?→D
15C→C
cos¯¹ (sin B * sin D
+ cos B * cos D * cos (A-C))→E
E>DMS
Example
Distance between
Regulus (A) in Leo and Sadalmelik in Aquarius:
(data via
Wikipedia)
Regulus: α = 10h8m23.11s, δ = +11°58’01.95”
Sadamelik: α = 22h5m47.03593s, δ = -0°19’11.4568”
Distance: 168°20’05.1793”
Source:
Meeus, Jean. Astronomical Algorithms William-Bell, Inc. Richmond, VA 1991. ISBN 0-943396-35-2
Please stay
safe, happy, and sane. Happy computing,
Eddie
I hope to have
the new Casio Prizm FX-CG50 soon for review as I ordered one last Friday.
This blog is
property of Edward Shore, 2017.