Using RA and DEC coords to locate objects

[badger111]

Here's my first nube question (and apologies if it's been covered elsewhere). I was outside last night and was finding objects using the finderscope, which was great for the objects I could easily see. Today I downloaded a list of the "Brightest Stars" which contained all their RA ad DEC coordinates. To locate them, is it just a case of polar-aligning my telescope and then dialing those coordinates into the mount (I have an EQ1 mount on my Sky Watcher) ?

[kerrylewis]

Yes - I'm not familiar with the EQ1 mount but if the handset is like other synscan ones there should be a 'user object' option where you can enter the coordinates. But does it not have the brightest stars named anyway?

[kerrylewis]

Sorry - looked it up and I could have looked at your picture. With no handset you put the coordinates into the setting circles. However, with a star atlas or planetarium app you should be able to locate the brightest objects with your finder. This is likely to be more successful. Even if you can't see the object that you want in your finder you can point at the right spot in the sky in relation to stars that you can see or star hop from brighter stars, if that makes sense. I would prefer this to setting circles

[badger111]

Thank you for you answer. It was my first venture out and I struggled to align the telescope with what I could see with my eyes. I'm also ashamed to admit that I didn't realise that the image was upside down either; it wasn't until I saw a satellite zip past with my eyes and then saw it zip the other way through the telescope that It acutally dawned on my that the image was upside down (it also made finding stuff easier when I worked this out too)....

[kerrylewis]

There is a lot to get used to! Is your finder a red dot and therefore right way up? I find it preferable to do the initial locating right way up as this corresponds with what you can see. Then with the magnified image it doesn't matter so much that it's inverted or back to front.

It helps to learn your way around the sky 'right way up' then point the scope where you want to go (making sure that the finder and scope are lined up) and then the target should be there and it doesn't really matter which way up it is. Star hopping is slightly more difficult unless you do it all with the finder - but one step at a time.

Good luck - the main thing is to enjoy it!

Kerry

[badger111]

Thanks Kerry - Yes it is a red dot finder. The problem I was having was, I could see the red dot but I couldn't see the stars through it that well. Do you have to put your eye quite close to it? I was trying to aim it like a riffle.

[kerrylewis]

I've not used one for a while but I have a Telrad which works on a similar principle. You don't have to get too close but rather try and see the red dot superimposed on your general view if the sky if see what I mean.

[ollypenrice]

Hang on, is this mount motorized? If not you can only use your setting circles for a brief time and then only after setting them on a bright star adjacent to your target. In a nutshell they are not much use and nobody uses them on undriven mounts. On undriven mounts you place the scope on a bright star near your target, set the settng circles to the co-ordinates of that star, then quickly move the mount to the co-ordinates of the target before time (or really the movement of the earth) has made them out of date. In truth they are so incaccurate on this mount (and on mounts several steps upmarket) that they don't get used. Digital setting circles (as dislayed on the handsets of the dearer mounts) are a different matter and are worth using. You are unlikely to find mechanical setting circles at all helpful even on a driven mount when, once you have set them to the position of a known star, they will reamain valid over some time.

Olly

[Moonshane]

I tend to agree with Olly but give it a try. I don't use setting circles but star hop to targets. Any star map will have co-ordinates in and you can work out where the target is and star hop from brighter stars

[acey]

Setting circles on amateur scopes are not accurate enough to locate a specific target from its RA and Dec co-ords. GOTO should be accurate enough to get it into a low power FOV.

If you want to find a specific target and you've got its RA and Dec co-ords, then look it up on a map. Star charts have RA and Dec as their axes (like longitude and latitude on a terrestrial map) so it's just a case of finding things on a grid, then star-hopping to that location from a naked-eye star whose position you can see on the map.

If your list is of "brightest stars" then the best way to locate them is using your naked eye and a naked-eye star chart. For finding things with a telescope the S&T Pocket Atlas is excelllent and well worth getting.

[badger111]

Hang on, is this mount motorized? If not you can only use your setting circles for a brief time and then only after setting them on a bright star adjacent to your target. In a nutshell they are not much use and nobody uses them on undriven mounts. On undriven mounts you place the scope on a bright star near your target, set the settng circles to the co-ordinates of that star, then quickly move the mount to the co-ordinates of the target before time (or really the movement of the earth) has made them out of date. In truth they are so incaccurate on this mount (and on mounts several steps upmarket) that they don't get used. Digital setting circles (as dislayed on the handsets of the dearer mounts) are a different matter and are worth using. You are unlikely to find mechanical setting circles at all helpful even on a driven mount when, once you have set them to the position of a known star, they will reamain valid over some time.

Olly

Hi Olly - Thanks for the info. I suspected that settings circles were quite inaccurate - especially when it's the middle of the night and you're shining a red torch on microscopic numbers on a budget mount. I was kind of hoping to learn my way around the sky by drawing up a list of "targets" using their Ra+dec coords during the day and trying to find them during the night with the telescope. The problem I was having (and still have) is, whilst I can find them by eye I have real trouble seeing them through the telescope - I know it sounds strange, but I really struggle with the fact that everything in the scope in inverted

[Billy Bluelight]

Hi Badger,

As one newbie to another, has anyone ever suggested an excellent book called "Turn Left at Orion?  

It makes it so easy to locate almost anything by star-hopping from one easy to find object to another.  Can be bought new or used on Amazon here http://www.amazon.co.uk/Turn-Left-Orion-Guy-Consolmagno/dp/0521482119/ref=sr_1_3?s=books&ie=UTF8&qid=1408915266&sr=1-3&keywords=turn+left+at+orion and there is an updated version for greater cost.  It might be useful?

[badger111]

Hi Badger,

As one newbie to another, has anyone ever suggested an excellent book called "Turn Left at Orion?  

It makes it so easy to locate almost anything by star-hopping from one easy to find object to another.  Can be bought new or used on Amazon here http://www.amazon.co.uk/Turn-Left-Orion-Guy-Consolmagno/dp/0521482119/ref=sr_1_3?s=books&ie=UTF8&qid=1408915266&sr=1-3&keywords=turn+left+at+orion and there is an updated version for greater cost.  It might be useful?

Just what I need - thank you

[timwetherell]

Setting circles on amateur scopes are not accurate enough to locate a specific target from its RA and Dec co-ords. GOTO should be accurate enough to get it into a low power FOV.

.

Unless they're very big ones, yes, that's exactly right. On my old 60mm refractor the circles would get me within 10° if I was lucky which wasn't that helpful. That's why on the mount I build I used 8 and 12 inch circles. Even with less than perfect polar alignment that get's me within about 0.5° 

[timwetherell]

Thank you for you answer. It was my first venture out and I struggled to align the telescope with what I could see with my eyes. I'm also ashamed to admit that I didn't realise that the image was upside down either; it wasn't until I saw a satellite zip past with my eyes and then saw it zip the other way through the telescope that It acutally dawned on my that the image was upside down (it also made finding stuff easier when I worked this out too)....

Nothing to be ashamed of at all! We all start out with much to learn. Welcome to what will hopefully be a very rewarding hobby for you  

[elrico]

Can or is it possible to locate objects by Dec and RA with a Dobsonian   

[Digger1895]

Elrico, I added very a very simple azimuth circle on my Dob base and used an inclinometer on my phone for altitude and got way better than expected results.

[elrico]

Thanks I will look into that as a possibillity for me

[Digger1895]

Elrico, if you go to this site

settingcircles.robertwillett.com:8000

You can put in any radius you like and it will give you the az setting circle to be printed out. He has loads of different stuff on there and scales for altitude too if you need or like that idea.

From memory you have to register but I didn't need to pay for anything I wanted.