# How to find the position of a celestial object in the sky?

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• Xinran Li
In summary, the electrical engineering student is researching how to find a specific star in the sky. They need information about their location, time, right ascension and declination of the star, and the telescope needs to be leveled and pointed at true north. After finding the star and calculating the coordinates, the student would use a telescope to find the object.
Xinran Li
Hi all,

I am an electrical engineering student currently involved in a project aimed to create a simple GoTo azimuth mount. I don't have a lot of background in astronomy, so I am a bit confused on how to find the position of a star in the sky.

After some research on my own, I figured out that the following information is necessary (maybe not enough):

1. My location on earth

2. Time in my current time zone

3. The right ascension and declination of the star I would like to find

I was then confused by a flood of astronomy vocabularies. In order to understand the process better, I really need a concrete example.

So for example,

I am located at 40.4259° N, 86.9081° W, and I wish to find Andromeda galaxy (RA = 00h 42m 44.3s, Declination = +41° 16′ 9″, I found this data on Wikipedia) on the sky at 1:00 AM EST January 13th, 2019. Assume we have the telescope calibrated and pointed at the north pole star (I am not sure if this is enough as a reference point), how would I move the telescope to find the Andromeda galaxy then?

This might be a terrible example, I am just writing down some random numbers and time hoping it might work. If you think this example is wrong, please please provide a similar example! I really need to work through some examples to be able to understand all these! Thanks a lot in advance!

Hi Xinran

Not an astronomist myself either. But the
Xinran Li said:
flood of astronomy vocabularies
appears to be all clickable. So either ask a specific question when you get stuck at some particular point, or grab a textbook and study the base material. PF is not intended as a resource for the latter but as a place to ask questions about stumbling items in there.

This calculator may be of use. Given the RA and Dec of the object, your latitude and longitude, and your local time, it will calculate the altitude and azimuth of the object. For the example you gave, the Andromeda galaxy has an altitude of about 63 degrees and an azimuth of about 76 degrees. So it is 14 degrees north of due east, and 63 degrees above the horizon. Normally for an object like the Andromeda galaxy, you would find it with your naked eye or a pair of binoculars and aim the telescope at it manually. To point the telescope using GoTo mount is more complicated and depends on the details of the mount and the telescope.

Edit: If you're trying to create a GoTo alt-azimuth mount, then you need two things. You need the mount to be level, as this sets the plane of the horizon and hence the altitude. Second, you need to find true north to set the zero point of azimuth. Once you have those two things, you calculate the altitude and azimuth of the object using the calculator I linked, and go to those values. Note that the site I linked has the necessary formulae below the calculator itself.

Last edited:

## What is the best way to find the position of a celestial object in the sky?

The best way to find the position of a celestial object in the sky is by using a star chart or a planetarium software. These tools can show you the exact location of the object in the sky at a specific time and date.

## What information do I need to find the position of a celestial object in the sky?

To find the position of a celestial object in the sky, you will need to know the date, time, and your location on Earth. This information is necessary for accurate calculations of the object's position in the sky.

## How do I use the celestial coordinates to find the position of a celestial object in the sky?

Celestial coordinates, such as right ascension and declination, are used to locate celestial objects in the sky. You can use these coordinates to find the object's position using a star chart or a planetarium software.

## Can I find the position of a celestial object in the sky without any tools?

Yes, you can estimate the position of a celestial object in the sky without any tools by using your hands. Hold your hand at arm's length and use your fingers to measure the distance between the object and the horizon. This method is not as accurate as using tools, but it can give you a general idea of the object's position.

## What is the difference between the altitude and azimuth when finding the position of a celestial object in the sky?

The altitude is the angle between the horizon and the object, while the azimuth is the angle between the north direction and the object. Both coordinates are used to determine the position of a celestial object in the sky, and they are measured in degrees.

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