How to use RA and Dec to locate objects

[localhost]

This guide is for Celestron Computerized Telescopes, to follow this guide you must already have a Telescope made by Celestron that has a NexStar+ hand controller.

Video if you prefer visual guide.


Someone once asked me is there any way to find objects that are not in the hand controller, technically everything is programmed into the controller, you just need the right Ascension and declination settings, to locate the object .
So for example, let's say you wanted to locate a comet, you first need to do your alignment, then you can proceed to use the right Ascension hour, minutes, seconds and declination hour, minutes, and seconds.

Let's begin by sitting up our telescope if you haven't done this already, I assume your scope is Now setup, proceed to doing your alignment, for better accuracy I'd recommend a two star alignment.

At this point I assume that you have already done your two star alignment, Now go to the menu button, scroll through the menu until you find Goto RA-Dec.

Press enter, this section will allow you to enter in the right Ascension, hour, minutes, and seconds.

After you enter the right Ascension hour, minutes, and seconds, you will be asked to enter the declination hour, minutes, and seconds.

I am sure you're curious to know how do you find out the right Ascension hour, minutes, seconds and declination hour, minutes, and seconds.

You can check out this website called https://theskylive.com before you use this website, the website has a location area, you need to change this to where you are, so if you were in Florida you would set it location to Florida.

See picture below.



it's really important you update location, otherwise you will have the wrong coordinates where the object is.
You can see in the screenshot for Comet 21p there's a right Ascension hour, minutes, seconds and declination hour, minutes, and seconds.

This is the information you want to enter into the hand controller, if your alignment is good, and you set the correct location on that website https://theskylive.com , once you slew to the object, you should see it in the eyepiece.

if you don't see the object, when your alignment is off object is too dim.

This guide will only work with Celestron series mounts, that have a nexstar Plus controller.

[Aratus]

That's very useful. Thank you. Coordinates are often in RA(now) and Dec(now) which is the one folk need to use. Sometimes you get them in RA(2000) etc, then it will not be so accurate. One problem is that these coordinates can be presented in either in decimal hours, or minutes and seconds of arc. It is best to make sure that the handset and web site are giving and using the same units! I have been stumped with that in the past, having to make approximate conversions on the hoof!

[JayTee]

it's really important you update location, otherwise, you will have the wrong coordinates where the object is.

It is important for you to input your correct location to get "local" information like rise/transit/set times. However, the RA and Dec for an object remain the same where ever on Earth you may be observing. RA and Dec describe a fixed point in the celestial sphere. It does not change when you change your location. Now if you were using altitude and azimuth as your method for pointing your scope then having the correct local coordinates is essential.

Give a try and see. Use Greenwich and Honolulu as your two observing sites and choose an object of your choice you'll see that the RA and Dec do not change.

Hope this helps,
JT

[KathyNS]

it's really important you update location, otherwise, you will have the wrong coordinates where the object is.

It is important for you to input your correct location to get "local" information like rise/transit/set times. However, the RA and Dec for an object remain the same where ever on Earth you may be observing. RA and Dec describe a fixed point in the celestial sphere. It does not change when you change your location. Now if you were using altitude and azimuth as your method for pointing your scope then having the correct local coordinates is essential.

To be fair, the comment you quoted was in reference to an example of a comet. For rapidly-moving objects like nearby comets, the coordinates are time-dependent and therefore will vary by location.

Your correction is right when talking about stationary or slow-moving objects.