- #1

alseth

- 15

- 0

My data:

Star A: Arcturus(α Boo)

Right ascension: 14h 15 m 39.7s

Declination: +19° 10' 56"

Time: 19:31:11 UT

Elevation: (100-89.9)*0.9= 9.09°

Elevation after the refraction correction: 9.0°

JD1 = 2455097.31332

Star B: Mirfak (α Per)

Right ascension: 03h 24m 19.4s

Declination: +49° 51′ 40″

Time: 20:05:29 UT

Elevation: (100-61.5)*0.9= 34.65°

Elevation after the refraction correction: 34.62°

JD2= 2455097.33714

script:

# 1 rad

rad=180/pi

# 90degrees-elevation

r1 = 81

r2 = 55.38

# coordinates of the first star

# Arcturus, a1 = a1 - ts

a1 = 213.92 - 15*(19+(38/60)+(20.2/3600))

d1 = 19.18

# coordinates of the second star

# Mirfak

a2 = 51.081 - 15*(20+(12/60)+(43.9/3600))

d2 = 49.86

# their distance

rad*acos(sin(d1/rad)*sin(d2/rad) +

cos(d1/rad)*cos(d2/rad)*cos((a2-a1)/rad))

# first estimate of the geographical location

a = 16

d = 50

for i = 1:3

t1=sin(d1/rad)*sin(d/rad)+cos(d1/rad)\

*cos(d/rad)*cos((a-a1)/rad)

t2=sin(d2/rad)*sin(d/rad)+cos(d2/rad)\

*cos(d/rad)*cos((a-a2)/rad)

p = [ rad*acos(t1) - r1,

rad*acos(t2) - r2]

sqrt(p(1)**2+p(2)**2)

# susbstitution

u = -1/sqrt(1 - t1**2)

v = -1/sqrt(1 - t2**2)

# derivation matrix

m = [ -u*sin((a-a1)/rad)*cos(d1/rad)*cos(d/rad),\

u*(sin(d1/rad)*cos(d/rad) - \

cos(d1/rad)*sin(d/rad)*cos((a-a1)/rad));\

-v*sin((a-a2)/rad)*cos(d2/rad)*cos(d/rad),\

v*(sin(d2/rad)*cos(d/rad) - \

cos(d2/rad)*sin(d/rad)*cos((a-a2)/rad))]

# inverse matrix

[im,c] = inv(m)

# linear equations

x = -(im*p)

# and addition to the initial estimates

a = a + x(1)

d = d + x(2)

endfor

ts is apparently the sidereal time a and r1, r2 are 90 degrees minus elevation

The observer should be around 16.6 degrees east and 49.2 degrees north but I am getting very imprecise values. Even some parts of the script do not seem to e doing anything. Is there some error there or maybe is there a more elegant way to do the computation?

Thanks for any help.