Astronomical coordinates and planning observations Ijorge/aga5802_2017/2017_05_coordenadas1.… ·...
Transcript of Astronomical coordinates and planning observations Ijorge/aga5802_2017/2017_05_coordenadas1.… ·...
AGA5802 Astrofísica Observacional
Astronomical coordinates and planning observations I
Bibliography: Any book (or chapter) on coordinates.
Some basic astrometry in slides from Prof. Roberto Boczko + myself (Elementos de Astronomia):
http://www.astro.iag.usp.br/~jorge/aga205_2011/
Prof. Jorge Meléndez 1
Iguazu falls http://www.twanight.org
http://apod.nasa.gov/apod/ap100514.html
Finding the South
-50 -55 -60 -65 -70 -75 -80 -85 -90
14h
15h
16h
Finding the South
-50 -55 -60 -65 -70 -75 -80 -85 -90
14h
15h
16h
Local coordinates
Linha do
Horizonte
Zenith
Nadir
Vert
ical
Slide adapted from Prof. Boczko
Local Meridian
Zenith
N S
E
W
Nadir
Horizon
Is the semicircle
passing through
the points
zenith, N and S.
Slide adapted from Prof. Boczko
Altazimutal System Azimuth (A): N E S O(W)
Fig. 3.2 from Astronomy Methods
Altitude (h):
-90o a +90o
Altitude & zenith distance
Horizon
Zenith
Nadir
S
W
E h = altitude z = zenith distance
z
N h
Altitude is the angle between the local horizon and the object
Zenith distance is the angle between the object and the zenith
h + z = 90o
Slide adapted from Prof. Boczko
l
j < 0
j
NP
SP
Greenwich
North
East
(S) -900 j +900 (N)
0 l +1800 (E, W) (W) -1800 l +1800 (E)
Longitude l
Geographic system
Latitude j
Slide adapted from Prof. Boczko
Sampa? 23.55° S 46.63° W
How to find the Latitude
j
hPole
Slide adapted from Prof. Boczko
The altitude of the pole is the latitude of the observer
La Silla/ESO (3,6m telescope) 29.2612° S, 70.7313° W on 2014/01/12 © J. Meléndez
j
Equatorial
system NP
SP
g a
d
(a , d ) p
a = right ascension
d = declination
p = polar distance
p + d = 900 N
E
Slide adapted from Prof. Boczko
Zero point
for R.A. :
intersection
of ecliptic &
equator
Polo
Celeste
Norte
Sun
Equatorial
system
g Vernal equinox
Obliquity of the ecliptic
23o 27' 08"
Equatorial
coordinates
Fig. 3.1 from Astronomy Methods
Units
1 hour 150
0h a < 24h
00 a < 3600
Right Ascension Declination
(S) -900 d +900 (N)
(N) 00 p +1800 (S)
Polar distance
Slide adapted from Prof. Boczko
Example: equatorial coordinates for
the Sun
g
W
1
2
NP
PNE
a = 6h
d = +
a = 18h
d = -
4 a = 0h
d = 00
a = 12h
d = 00
3
a = 6h a = 18h
SP Slide adapted from Prof. Boczko
Zero point is the Vernal equinox, about March 21
Horizontal & Equatorial system for
observer in the NH Z
NP
E
W
N S
Slide adapted from Prof. Boczko
Provinha 2 4. Plot both horizontal + equatorial system for an
observer in São Paulo. Show the horizontal and
equatorial planes, the zenith, the cardinal points and the
position of the Celestial South Pole
Local Meridian and Projection Z
SP
N S
E
W
Nadir
Horizon
Zenith
Nadir
Horizonte E W
SP
S N
Projection on the meridian plane
Slide adapted from Prof. Boczko
Hour circle: the great circle passing
through the object and the celestial poles NP
SP
Z
H d
( H , d )
H = hour angle
d = declination
p = polar distance
W
N S
E
p NP
SP
Observer in the
Northern H.
Slide adapted from Prof. Boczko
Hour angle H: the angle measured (on the
equator’s plane) from the local meridian to the object’s
hour circle
Units
(E) -1800 H +1800 (W)
1 hour 150
(E) -12h H +12h (W)
(S) -900 d +900 (N)
00 p +1800
Hour angle Declination
1 h = 15° 1 m = 15' 1 s = 15"
Provinha oral
3h 20m = 0 ‘ “? -300,5 = h m s ?
Culmination or Meridian crossing
NP
Horizon
W
S
At lower meridian crossing: H = 180o
L
SP
Z At upper meridian crossing H = 0.
M
N
Slide adapted from Prof. Boczko
Horizon
S
12
At lower
meridian
crossing
H = 12h
E
W
6
Z
0
At upper meridan crossing:
H = 0.
M
N
Example of hour angles
Ñ
1
2
3
4
5
11 10 9 8
7
SP
NP
Slide adapted from Prof. Boczko
Sidereal time: the hour angle of g
g
ST Hg
Horizon
W
S ST
Z
NP
M
SP
N
Slide adapted from Prof. Boczko
Sidereal day Z
SP
N
Interval for 2 succesive local meridian crossings
of g
Sidereal day 23h56m04s
E
W
Sidereal day 24h*00m*00s* * : sidereals
Sidereal
Midnight
Sidereal
Noon
Slide adapted from Prof. Boczko
Measuring the right ascension
at meridian crossing
NP
d
g
a
ST = Hg ST = a + H
At upper meridian crossing: H = 0
Then:
a = STMer.crossing
Horizon
W
H S
M
Z
SP Slide adapted from Prof. Boczko
Prof. Rama
Meridian
Circle at
Valinhos
Do it yourself: star in London with hour angle H = 3h & declination d = 15o?
PN
d Horizon
W
H S
M
Z
PS Slide adapted from Prof. Boczko
Do it yourself: star in London with H=3h, d=15o & a=1h30m, draw a
PN
d
g a
What is the sidereal time ST? Horizon
W
H S
M
Z
PS Slide adapted from Prof. Boczko
ST = 4h30m
Do it yourself: draw Orion as seen from São Paulo
(23.5° S, 46.6° W) at the meridian passage
32
-90
-80
-70
-60
-50
12
h
http://www.stellarium.org/
The Sky at OPD observatory
2013/03/22 18h
R.A. of the Sun? What time is it?
Which date?
Sky at OPD: altazimutal
2013/03/22 18h
+90
+80
+70 +60 +50
0
+40
+30
+20
+10
0
What are the coordinates
(A, h) of the Moon?
Where is the
celestial South Pole?
Sky at OPD: altazimutal + equatorial
2013/03/22 18h
Sky at OPD: equatorial
2013/03/22 18h
-20
-30
-40
-50 -60
-70
-80 -90
-10
0
6h
7h
8h
9h
10
h
11
h
12
h
1h
0h
Latitude = -22°30’
P.S.
Which are the coordinates (α, δ) of
the Sun & Moon ?
-90
-80
-70
-60
-50
12
h
h (pole) = |latitude|
Sky at OPD: equatorial
2013/03/22 19h
-20
-30
-40
-50 -60
-70
-80 -90
-10
0
6h
7h
8h
9h
10
h
11
h
12
h
1h
Latitude = -22°30’
P.S.
13
h
Which are the coordinates (α, δ) of
the Orion belt?
Sky at OPD: equatorial
2013/03/22 20h
-20
-30
-40
-50 -60
-70
-80 -90
-10
0
6h
7h
8h
9h
10
h
11
h
12
h
Latitude = -22°30’
P.S.
13
h
What is the hour angle (H) of Sirius?
Sky at OPD: equatorial
2013/03/22 22h
-20
-30
-40
-50 -60
-70
-80 -90
-10
0
6h
7h
8h
9h
10
h
11
h
12
h
Latitude = -22°30’
P.S.
14
h
13
h 15
h
At what time would be the meridian crossing of
the Southern Cross?
What is the R.A. and declination of Crux & a Cen?
Sky at OPD: equatorial
2013/03/23 0h
-20
-30
-40
-50 -60
-70
-80 -90
-10
0
6h
7
h
8h
9h
10
h
11
h
12
h
Latitude = -22°30’
P.S. 1
4h
13
h
15
h
16
h 1
7h
What is the sideral time?
Sky at OPD: equatorial
2013/03/23 2h
-20
-30
-40
-50 -60
-70
-80 -90
-10
0
8h
9
h
10
h
11
h
12
h
Latitude = -22°30’
P.S.
14
h
13
h
15
h
16
h
17
h
18
h
19
h
What is the R.A. of Scorpius' tail?
Sky at OPD: equatorial
2013/03/23 4h
-20
-30
-40
-50 -60
-70
-80 -90
-10
0 10
h
11
h
12
h
Latitude = -22°30’
P.S.
14
h
13
h
15
h
16
h
17
h
18
h
19
h
20
h
21
h
22
h
What would be the hour angle (H) of Arcturus at
05:00 in the morning?
Sky at OPD: equatorial
2013/03/23 6h
-20
-30
-40
-50 -60
-70
-80 -90
-10
0
12
h
Latitude = -22°30’
P.S.
14
h
13
h
15
h
16
h
17
h
18
h
19
h
20
h
21
h
22
h 23
h
What is the R.A. of the East point?
Campos dos Goytacazes, RJ http://www.twanight.org
http://apod.nasa.gov/apod/ap090509.html
Imagine the equatorial system on the sky!
Ecliptic system
PNE
W
N
L
b
( ℓ , b ) 00 ℓ < 3600
(S) -900 b +900 (N)
ℓ : ecliptic longitude
b : ecliptic latitude
g
ℓ
Slide adapted from Prof. Boczko
Equatorial & Ecliptic System
NP
EPN
W
NP EPN
g
N
E
g
W
Slide adapted from Prof. Boczko
Galactic system ( ℓ , b )
© Astronomy Methods
ℓ b
Exemple drawing
50
Dec = lat
Zenith
Horizon