Setting Circle Help!

[crazyjedi]

Hi all.

I've always star hoped my merry way around the sky but recently

i've been hunting some seemingly elusive prey. There are a number of galaxies around the plough and i can't find one of them. I live near the M5 motor way and hence have terrible light pollution so i don't expect much detail but i can't find one of them!! would setting up my settin circles help much? Even when i'm at my caravan in wales with far less light pollution i can't clap eyes on Bode's galaxy or the pin wheel or any of them.

I'm gettin pretty frustrated

If setting circles are the way to go, is there a tutorial anywhere or a kind soul willing to walk me through the whole hoopla?

My mount is a plain old Celestron CG5 with no computer guides or gizmos

[david o]

Hi Rob,

From other posts and general trawling of the web, I'm led to believe that the setting circles on the CG5, and other modern Chinese mounts, are far too small to be even minimally useful.

Apparently something precisely engraved, in the region of 6 - 8" diameter, is considered the smallest usable kit.

Rob Mollise in his book The Urban Astronomer's Guide, suggests at least 8".

HTH

[yeti monster]

As far as I have been able to deduce, RA should be set on a prominent star of known RA (Betelgeuse @ 5h 55m ish, or Beta Auriga @ 6h, for example) Then move the scope on the RA axis until it is aimed at the RA value of the selected target. Then set DEC to suit the target. This should have you in the correct area of sky. But as the setting circles are so teeny and in accurate, this will only have you in the neighbourhood.

I've never bothered doing this, but shall give it a go some day..........

[JamesM]

Hi Rob,

I agree with David O, the circles aren't large enough to warrant using - I would go so far as to say they're for show purposes, to make things look more 'technical'. Now I've have borrowed a scope (4" reflector ) smaller than yours so I know what its like trying to find these galaxies.

Like you I have no GOTO and have to rely on maps to find my way around. Those you see in Sky at Night and the like, are in my view not detailed enough (....they're meant to be just indicators of where to look). I would suggest you buy a good large star map with plenty of detail. When you start looking through the scope you see a darn sight more stars, but they can be your signposts IF the map you have matches what you see!

Now this is going to sound odd but what I do is to use binoculars to take a closer look at the area of sky my target is supposed to occupy and adjust my scope to put it into that same general area. Now I don't have a red dot finder etc to do this easily and my spotter scope inverts things which for me, if I could get my head next to it, just adds to the problem! What I use instead is a laser pen, attached to my scope with a clothes peg to switch it on and off. So I switch the laser on, and with my binoculars held in one hand, I use the other hand to move the scope closer to my selected area so that the laser starts to point at a collection of stars whose pattern I recognize from my map I just looked at. I then switch off the laser and go and have another look at the map to where to move next. I keep repeating this process of switching on and off the laser moving the scope closer each time (...using the map each time to walk or 'star hop') until I am right on the spot where the galaxy should be.

Now some people might scoff at this system but it works for me and I will tell you why. As a newbie I find it difficult looking up at the sky whilst trying to aim my little scope at something that I can't see and don't even know that I will be able to resolve when I finally get there. A small aperture and light pollution can kill off any intended target so you could be there all night - I know I've done it. What used to happen would be that I would look down at the map but then get lost because I had taken my eye off the bit of sky I was last looking at! My system allows you to press the pause button as it were, so that you can look down at the map to work out where to go next, turn the laser back on, follow it's path from the scope with the binoculars to the point where you last left it (..last observed), then move it on a little closer towards the target. It also means that if you're not sure where to go, the laser effectively holds your position whilst you go and have another look at your map. I turn the laser on and off also to save on the battery and to minimize my activity so that the flapping net curtains of my nosey next door neighbours don't blow my scope over!

I thought I would share my technique with you Rob as I know how tricky all this can be. However, It is worth it and when you do find them, it can feel brilliant, its like you've caught one in your hands. Let me know how you get on!

Clear skies

James

[Moonshane]

Now this is going to sound odd but what I do is to use binoculars to take a closer look at the area of sky my target is supposed to occupy and adjust my scope to put it into that same general area.

I live in between the LP of Manchester and Stockport and can see M81 and M82 (just) with my 10x50 binoculars.

Try it and you'll be surprised I bet.

I also found that a Telrad / Rigel transformed my ability to find stuff.

[gareththegeek]

So far every DSO I have found has been using the setting circles on my CG-5. They are a little inaccurate but they get you pretty close as long as you are patient and careful in aligning them.

I usually look up the coordinates for two prominent stars nearby to the DSO I'm interested in as well as the DSO itself. I point the scope at one star and move the setting circles to read the correct coordinates. I then try to point the scope at the second star and check the circles read the correct coordinates. This can be repeated until you have got the circles pretty accurate.

I then set the RA for the star and move on to the DSO. If I don't see it I just scan in RA a bit either direction (because the DSO is moving while you are looking for it).

I find the trick is to try and get the DEC axis aligned as accurately as possible. That way you only have to scan in one axis (RA). If all else fails I try moving one 'scope width' up or down in declination and scan again in RA.

HTH

[crazyjedi]

I have 'The Cambridge Star atlas by Wil Tirion which is very good as a general text but seems difficult to relate to my light polluted sky's of suburban birmingham. I rely heavily on Stelarium for actual day by day guidance. But as i say, i've had no luck hunting these galaxies i totally relate to what has been said about that first view of a new night sky object. My first sighting of the Orion nebula or the view of Jupiter or Saturn has left imprints upon me. I've been hunting those galaxies on and off for about a year so i' pretty desperate now. James's method ( you should call it that) seems like a good idea, I'll borrow my mom's binoc's and get a laser pointer asap.

I'm Going to persevere for a while with the setting circles for a short while until i get my laser pointer simply cuz i hate giving up.

Well i will when the cloud's go away

TTFN

[Moonshane]

hi Rob

I find that the sky in one direction can vary massively to another in terms of LP. if you let me know where your darkest bits are I can see if I have seen a galaxy in that area and if I can come up with some guidance on tracking one down. I reckon once you see one and know what to expect you'll start to pick more up - they are going to be very faint though in a badly polluted sky. another option is wait for Andromeda in late summer. you should be able to pick this one out in most skies.

[crazyjedi]

I could not find Andromeda all winter The constellation is easy enough to pick out as two long- slightly crooked lines of stars and i know M31 is between the top line of brighter stars and the bottom of Cassiopeia but i couldn't find it

[stev74]

I also found that a Telrad / Rigel transformed my ability to find stuff.

I agree totally with Moonshane I bought a Telrad and it's made a huge difference in finding DSO's. You can get free maps online with the Telrad circles printed on them, which really help with star hopping. There's a good write up here - Telrad finder and you can get the maps here - Messier Maps and just print the ones you need.

To be honest though galaxies are not the easiest objects to hunt and you really need dark skies and aperture to view them best. I have managed to bag a few from my garden (with the help of the Telrad) but they really do just appear as faint grey smudges.

From badly LP skies I'd concentrate on planets, brighter DSO's such as star clusters and double stars. I'd also recommend finding out if there are any astro societies or observing groups in your area. They will have dark sites already scouted out and experienced stargazers, both of which would be a great help with your galaxy hunt.

Lastly we've all been where you are and had frustrating nights, in fact I still do. Keep at it though and the more objects you find the easier they become to find the next time.

Good luck

[yeti monster]

OooooH! Them Telrad maps look rather handy!

[stev74]

Yes, very handy.

Although I did forget to mention it's a good idea to get them laminated or at least keep them in a clear plastic A4 bag. That way they don't turn to mush with all the dew which plagues us UK stargazers!!

[yeti monster]

A laminator is on my shopping list, has been for a while actually, just never got round to buying one as I generally just do it at work..........