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RA and DEC coordinates


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SO..................

in a week it will be time to get a proper telescope :) im quite excited lol im going for a 150p on a eq3-2 also going to get a polar scope with it, ive been getting ready for its arrival with some new targets, supernovae and some messier, after looking on wiki and various places for the remnants i notice they give RA and DEC coordinates, but am i not right in saying these move dependent on time and place on earth?? if using something like this what is the best way to find them, im not saying that im going to be able to see them just want to try but to try i need to know where they are!!! any help would be great :)

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RA and Dec are like Longitude and Latitude on the surface of the Earth but on the "surface" of a huge sphere surrounding the Earth upon which we see the stars. It is a way of giving a specific position to a star (or planet etc) as seen from earth. Unfortunately the Earth spins on its axis so this whole sphere seems to move round with time. You can calculate positions if you know the siderial time of your position on Earth.

For the purposes of practical Astronomy it is far easier to learn a few main "signpost" stars - usually a few bright constellation patterns - and use the "star-hopping" method of finding more elusive objects. You can make your own "finder charts" to help you (using a planetarium program) or download ready made finder charts from the web.

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RA and Dec are like Longitude and Latitude on the surface of the Earth but on the "surface" of a huge sphere surrounding the Earth upon which we see the stars. It is a way of giving a specific position to a star (or planet etc) as seen from earth. Unfortunately the Earth spins on its axis so this whole sphere seems to move round with time. You can calculate positions if you know the siderial time of your position on Earth.

For the purposes of practical Astronomy it is far easier to learn a few main "signpost" stars - usually a few bright constellation patterns - and use the "star-hopping" method of finding more elusive objects. You can make your own "finder charts" to help you (using a planetarium program) or download ready made finder charts from the web.

So i am kinda right lol ok so the turn left at orion method is proberbly best, i use stellerium but that is set on my position all the time so instead of my position moving the stars do, but i see what you saying, find a common star object i already know near its place and turn left/right at this star up/dorm from here kinda thing :)

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A good way to visualize RA-DEC coordinates is to turn on the RA-DEC grid in Stellarium by pressing the "E" key, then speed up time a bit by tapping "L" a few times. You can see that the coordinate grid rotates with the stars, and all the "longitude" (right ascension really) lines meet at the celestial pole (i.e. near Polaris if you're in the northern hemisphere). You can also turn on the ALT-AZ grid by pressing "A" and see the difference between the two systems.

RA-DEC is useful for defining the positions of objects in an absolute way. For instance, if I discovered an asteroid or something it wouldn't be very useful if I told you its position in terms of altitude and azimuth, because it would appear in a different position in the sky depending on your location and what time of night you chose to look for it. RA-DEC coordinates can always be translated to any observer's local coordinates.

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I was originally abit concerned about all of this myself, as my scope does not have RA or DEC labled on it, instead just having degrees for up and down and nothing for left and right, but it seems like 'star hoping' and just being used to the night sky should be enough to get going.

If you get yourself a good star gazing program on your computer, you can use objects of reference that you already know and work from there. For example I have a program called 'Stars' (I think) that I downloaded from the windows 8 store that not only shows you exactly where to look in reference to other things in the sky, but can also give you RA, DEC, Alt and Azi depending on what you need. Its also has the function to speed up or slow down time so you can plan ahead and for 99p was quite a bargain.

Its all about finding out finding the right guide to work with what kit you have and if you like working from books, websites, or something abit more interactive.

Personally, I prefer interactive all day.

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