Finders and other support for star-hopping under urban skies

[Druid]

So I have a 4" refractor and I'm trying to get the hang of star-hopping under conditions of fairly severe light pollution.

What I think I need is: a) a red-dot or some other sort of reflex sight to get me in the area and then something like a 10x50 RACI finderscope to star-hop with.

I'm sure others have faced and solved the same sort of problems though, so I'm keen to hear advice if anyone has alternatives or specific recommendations about a) and ... ?

[NGC 1502]

The combination of red dot finder or Telrad, plus a 10x50 optical finder is a very good one.

But I would add the lowest power, widest field eyepiece. If you can get a 2 or 3 degree field, then the scope is effectively a 4 inch finder. Lots of deep sky objects are easily visible at that low power, even under a town sky.

A good star map is needed too. Some use Stellarium with a laptop. I prefer a printed map & a dim red torch.

From a town, moon & planets are well seen, double/multiple stars too. Loads of DSOs are within your grasp, but of course a dark country sky would be better.

How about getting or making a solar filter ? It fits over the front objective, make certain it cannot dislodge. Then you are all set for daytime solar observing, and light pollution is irrelevant.

Good luck Ed.

[Pyrodave]

Hi Druid ,

I've not got one myself but there are alot of people that swear by a telrad they get good reviews

[Tinker1947]

A Telrad, used with the free downloadable Telrad maps they show the circles inposed on all the Messier Objects, and the free Stellarium its a great way to star hop, bring up the Telrad circles in Stellaruim (press F11 then Alt-O) select Telrad and your on your way.....

[nightvision]

All the above work well, I also use a laser pointer, the pointer is attached and aligned on my dob and I do the following: Use my 10x50 bins to locate the area of interest, drag the dob and laser on to the area of interest (the beam shows up great in the bins, the laser switch is held on by a tie-wrap, sliding this turns the laser off), I then move to the dob, switch off the laser and view the target. Alternatively I have the laser on a tripod and move and look for the beam with the bins and then the dob, both approaches work well. Sometimes other observes will spot something of interest and having the pointer mounted on something makes it easier for everyone to swing on to it.

[Druid]

I've seen mention of lasers and they seem like they might be very workable, but not sure I fancy a visit from an armed response unit.

They're a bit funny about lasers in these parts since this happened ...

http://www.liverpoolecho.co.uk/liverpool-news/local-news/2009/08/18/liverpool-laser-yob-who-targeted-police-helicopter-is-facing-prison-100252-24463258/

http://www.liverpoolecho.co.uk/liverpool-news/court-news/2010/10/01/huyton-teenager-admits-shining-laser-at-police-helicopter-100252-27377235/

[Druid]

Heh, just noticed you *are* in these parts. Oh well. I guess you don't use it on match days when the helicopter is flying?

[rowan46]

size wise you may find a rigel quick finder fits your scope better as a telrad has a larger footprint

[nicks90]

alternatively buy a cheap 0.5x focal reducer and screw it on to a 25mm ep and bingo, you would have about 5deg field of view - same as a reflex sight - and a much bigger light grasp.

get the target roughly centered and just swap eye pieces.

[Moonshane]

the problem I have with refractors and star hopping was the right left reversal; I just could not follow maps. I'd recommend RDF and right and correct image (RACI) optical finder combined. works a treat for me.

[glowjet]

A good combination is a Williams RDF and a 9X50 RACI finder scope together with a good star map such as Sky Atlas 2000, or better Uranometria 2000. A copy of Robert Garfinkle`s " Star Hopping" will assist you in the art, this can be had quite reasonably priced s/h without causing damage to the pocket. If you did not know a lot about stars and what can be seen in the various Constellations, then you soon will. Another route which has been mentioned is the Telrad, a little on the big side but used in connection with the dedicated Telrad maps can also be most effective. Another very fine aid is to obtain a copy of "The Illustrated Guide To Astronomical Wonders" which costs less than TL@O , with your equipment set up for star hopping it will guide to innumerable targets in the Constellations for small telescopes, that will keep you busy for a very long while to come

John.

[Druid]

This is all very helpful thanks.

I have Stellarium indoors and Wil Tirion's "Cambridge Star Atlas" to use outdoors. New torch on order so I can use it properly. Looking at the charts, I think I was thrashing around about 10 degrees away from my target last time out.

I have seen several people saying Telrads aren't very useful in heavy light pollution because you can't see any adjacent stars in the circles most of the time. But I can see the sense of using a simple reflex sight (or laser pointer should I overcome my fear of overly excitable armed response units) to get me in the right place. The focal reducer idea is completely new to me, so I shall have a bit of a read about that approach. Seems like the Skywatcher 9x50 RACI is pretty cheap and well thought of for the price, so I'll probably go that route once I've conclusively identified and bought the necessary widget to mount it to the clamshell ring on my refractor. I'll have to wait for a reply from one of the vendors I sent email to about that though.

Seems like binoculars might also be an asset while doing this stuff. I could see the laser + binoculars approach being a potentially workable alternative to red-dot + RACI and binoculars are pretty useful things to have around if the wife decides to join me.

[glowjet]

Should you wish to use a laser, one simple way, which I have seen mentioned on this forum, is to shine it through the optical finder to locate your approximate position. Such a unit within EU regulations, 1mW to 5mW rating, used sensibly with care, there should be no problem

John.

[Druid]

Oh dear. Televue red-dot finder is a bit pricey isn't it?

Is it worth the money?

[John]

Oh dear. Televue red-dot finder is a bit pricey isn't it?

Is it worth the money?

I guess you are talking about the TV Starbeam here ?

It is very expensive and, even as a great fan of TV stuff, I'd say that there are a number of other good RDF's that cost a lot less and would do the same job. The challenge is to get them mounted on the NP101. I've seen standard Skywatcher type finder mounting shoes fixed to the Tele Vue tube clamp so that must be possible.

[Druid]

Yep, there appears to be some sort of adaptor. I've sent emails to a couple of TV dealers requesting clear identification of the right ones for e.g. Skywatcher 9x50 RACI etc.

[Druid]

So I've been thinking, 24mm eyepiece on a 102 x 540mm scope is pretty close to the fov of a decent finder.

First step therefore needs to be some sort of laser pointer or red dot finder (can't see the point of telrads or rigels due to light pollution)

So if I'm not going to spend silly money on a Televue Starbeam and assuming I can get a suitable mounting plate, what other zero-power finder should I go for if I want quality and no fuss?

Baader maybe?

[Qualia]

During the week I view from a roof top smack-bang in the middle of a city and many times use a small 4" frac. I have found the following to be the best way to capture DSOs:

i) Star Atlas: get yourself a decent star map. I find Star Atlas by Sky and Telescope indispensable. It's not that expensive, it's a piece of art in itself and it is extremely useful.

ii) Viewfinder: a 9x50mm, right angled correct image viewfinder is the business. This delivers stars right down to about 8 magnitude, even if you're in a LP area, meaning you’ll be able to see every star plotted on the Sky Atlas and when you move amongst those stars, your left is left and your up is up.

iii) Red-Dot Finder: either a Telrad or Rigel finder will be a big help. These can’t deliver more stars than your eyes alone can see, so if you're in an LP area, you're relatively limited. But, they really do speed up your finding, really do help judge where you are, but it must be used in conjunction with the findercope. Whether in decent dark skies or a light soaked LP area, one positions the bullseye or the other two rings in the proper place against the stars and you’re done. If you're out a little you can work out where you are by either looking through your viewfinder or the three ringed cirlces of the red-dot finder giving you varying degrees of the sky you're looking at. If it helps, you can make a plastic red-dot finder overlay for the Star Atlas or just print one of the free Telrad maps on the net.

iv) Long Focal Length EP: A long focal length, low magnification EP will be your star-hopping workhorse. The low mag EP should offer you sufficient sky to manage along with your star map and red-dot finder and ought to be able to pick out or hint at what you're hunting. I use an EP which offers about 1º true field, others may prefer a little wider.

v) Sketches: sketches are too often overlooked, but they ought to be viewed from time to time. These are generally produced by patient observers who are trying to get the visual image right, so the little drawings should give you a very good idea of what the DSO being hunted out will more or less look like.

vi) SGL & Books: there are so many books about it's hard to pick out any one of them and say, this is the best. There are those which give context and depth to what is being viewed, others a more practical working guide. On the latter front, many folk recommend, Turn Left at Orion. I never really bothered with it but others swear by it. The power of SGL in welcoming us, helping us, comforting, informing and guiding us cannot be stressed enough. It is a precious place of refuge and each of us have the responsibility to help nurture it and keep it that way.

vii) Jumping Tricks: there are some little tricks you can learn to find yourself about the night sky. For example, find the plough in Ursa Major and look for Merek and Dubhe, the distance and angle between these two is one step. Now count that distance, in that direction another 5 steps and bingo, you'll be with Polaris. Now go back to the Plough and find its end star, Alkaid. Take a jump and dive from her and the next brightest star will be Arcturus, and so on. Learning the big stars and diving quickly between them makes hunting stuff easier.

viii) Participation in the Virtues: if you can master patience you'll be a master of yourself and the night sky is a good teacher. She'll teach patience and careful watchfulness; she'll teach industry and care and above all the night sky teaches trust. Those stars and DSOs are not going anywhere quick. They won't desert you and they're not trying to deceive you. If you don't succeed one night, no worries. Don't be down hearted, you've probably already discovered something new about yourself, or perhaps your equipment, or the sky itself. And those stars and DSOs will be back to give you another chance, another day.

ix) Don't fight the clouds: stargazing can be a tiresome road and one can suffer for it and be grieved, but the worst we can do is add to this frustration and hit out and curse those things beyond our control. Cloudy, uneventful evenings are just that, nothing more and when we are older they will appear to us as a singular, non-descript event, yet shining from them like a host of gleaming stars will be those evenings where everything just seemed perfect and the universe at last could murmur to us its secrets.

I hope that helps a little. Good luck, and clear skies to you

[Druid]

Thanks

That is helpful. I appreciate the time taken.

[FenlandPaul]

viii) Participation in the Virtues: if you can master patience you'll be a master of yourself and the night sky is a good teacher. She'll teach patience and careful watchfulness; she'll teach industry and care and above all the night sky teaches trust. Those stars and DSOs are not going anywhere quick. They won't desert you and they're not trying to deceive you. If you don't succeed one night, no worries. Don't be down hearted, you've probably already discovered something new about yourself, or perhaps your equipment, or the sky itself. And those stars and DSOs will be back to give you another chance, another day.

ix) Don't fight the clouds: stargazing can be a tiresome road and one can suffer for it and be grieved, but the worst we can do is add to this frustration and hit out and curse those things beyond our control. Cloudy, uneventful evenings are just that, nothing more and when we are older they will appear to us as a singular, non-descript event, yet shining from them like a host of gleaming stars will be those evenings where everything just seemed perfect and the universe at last could murmur to us its secrets.

I hope that helps a little. Good luck, and clear skies to you Thank you Qualia - that's a piece of poetry!

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