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15
votes
3answers
3k views

Could someone explain RA/dec in simple terms?

The equatorial coordinate system isn't too complicated. However, for people new to this, it seems rather intimidating at first. Is there an easy way to explain it?
7
votes
1answer
5k views

Calculation of right ascension and declination

I am confused about this problem: If I see an object from Mount Teide (longitude is 16"30'E and latitude is 28"18'N) that passes the meridian (azimuth=0) at 5h (am) UTC, and I also know that the ...
4
votes
1answer
51 views

Low precision GMST formula clarification

According to the website http://aa.usno.navy.mil/faq/docs/GAST.php, a low-precision way of calculating the GMST is via the following formula: GMST = 18.697374558 + 24.06570982441908 D The website ...
2
votes
1answer
97 views

Which is the shape of the sky?

I'm a software developer and I'm developing a planetarium and the first thing that I don't know is: What is the shape of the sky? First, I though that it is a semi-sphere, but searching on Internet I ...
1
vote
1answer
33 views

how steady over time are right ascension and declination values?

I understand that astronomers use right ascension and declination for the position of stars. However both these values strike me as very anthropocentric and, more importantly, unreliable over time as ...
1
vote
1answer
40 views

Why is declination positive in the northern hemisphere?

Simple question -- why is declination positive in the northern hemisphere? Seems like it should've been called "inclination" since the word originated north of the equator.
1
vote
1answer
46 views

How to find maximum and minimum right acsension and declination based on the telescope's location?

If I am to apply at a telescope for viewing objects, how to determine (easily) what is the minimum and maximum possible RA and DEC visible from that telescope during that time of the year. For eg, ...
1
vote
1answer
200 views

Calculate Dec and RA of a star from Euler angles and GPS data

I have 9DOF sensor (accelerometer, gyroscope, and magnetometer) that gives orientation via Euler angles (yaw, pitch, roll). Along with GPS data (latitude, longitude, elevation, time) this is passed to ...
1
vote
0answers
60 views

Determining planetary positions on the celestial sphere by Right Ascension and Declination

How would one go about determining the position of the different planets in our solar system with respect to the celestial sphere based on the following data set? Is there a practical way to calculate ...
0
votes
1answer
35 views

an exercise from Spherical Astronomy by Smart

I want to solve this exercise from Spherical Astronomy by Smart: Prove that, in latitude 45°, the interval between the moment at which a star's azimuth is 90° east and the moment of setting is ...
0
votes
3answers
56 views

Need Simple equation for Rise, Transit, and Set time

I've been looking, unsuccessfully, for hours for a simple set of equations: Input: RA and Dec of an object Observers Lat and Lng Current Time Output: Rise Time Transit Time Set Time (and, ...
0
votes
1answer
35 views

Calculating Right Ascension and Declination from Latitude / Longitude / Time

I have a latitude / longitude / time of a location on Earth, I need to calculate the Right Ascension / Declination that's overhead at the time provided. So far I've found out that Right Ascension is ...
0
votes
1answer
96 views

Declination and Ascension - the Sun and Andromeda

If Andromeda is overhead at midnight, what is the right ascension of the sun? (andromeda is ar RA =1hr, Dec = +40). I thought I understood what Dec and RA were, but I can't think of how to start this ...
0
votes
1answer
31 views

Declination change due to precession

I have this problem: I want to calculate the declination of the star in the year 5000. And I know RA (right ascension) and Dec (declination) of the star right now. How can I calculate it using ...