How to Star-Hop

[Xaviermarch]

I managed to pop out for a couple of hours last night between clouds and thought I would try and spot some of the deep-sky objects around Cassiopeia that the latest Sky at Night magazine suggested. At least that was the plan - what I actually achieved was pretty much nothing.

I tried NGC 457, NGC 7789 and spent an age trying to find M52. The stars were twinkling which I think means the seeing was bad but some of these I should have been able to see with binoculars so I assumed a telescope would have been easy?

My main problem was trying to star-hop from the main stars in the constellation of Cassiopeia. I could visibly see the stars I needed to use to find these objects, but as soon as I look through the eyepiece I can see so many more stars and cannot work out which ones are the ones I should hop from. Does anyone have some techniques they use or advice to help a lost beginner?

I also have a problem working out how much of the sky I am looking at through my eyepiece. This makes it difficult to know how far I should be moving the telescope to move to my intended target. With a focal length scope of 900mm and my lowest magnification eyepiece, which is a 40mm Revelation Astro, what "amount" of sky can I see? All I ever see is a mass of stars!

[NGC 1502]

Not sure the specs of that eyepiece, but if it's a 40mm plossl 1.25" fit, it will

will show about 2 degrees of sky, or 4 moon diameters in your scope.

First thing is to make sure the finderscope is lined up with the main scope.

I find a red dot finder much easier to use. Using a star chart, note where your

chosen target is in relation to naked eye stars, then put your finder, ( red dot

or cross hairs if it's an optical finder) on that place in the sky as best as you

can judge. Hopefully your object will be somewhere in the field of view.

You can then change eyepieces if needed for a closer look.

HTH, Ed.

[DarkerSky]

I second that! Good advice there

[Uplooker]

I understand your difficulty, I suffer the same problem at times. I know where I want to go but as soon as you look through the EP there are just so many extrs stars that it just becomes confusing. I think perserverence is the best advice - it does get easier. Just think what its like the first time you find M31, from then on you think, why was it so difficult to find in the first time. Because after that you can go straight to it.

[Mark at Beaufort]

I support what has been stated. My system is a red dot finder and a 9x50 correct image right angle finder.

I have produced overlay circles which correspond with the FOV of my finderscope and eyepieces. If you use a star atlas like 'Sky and Telescope' pocket atlas you simply place the main star inside the circle and then check that the image in the finderscope/telescope is the same. Keep checking the atlas and move the finderscope in the right direction and you eventually get there.

I used this system to find all the Messier objects and now finding Herschel 400 objects although I do use a more detailed atlas to find the fainter objects.

Mark

[Doc]

Are you using a laptop with a planetarium application on it. If so this is what I do.

1. Orientate the planetarium view exactly with your eyepiece view.

2. Dim the stars to in the planetarium to what you can see through your eyepiece.

3. Then it's simple procedure of locating different star formations and corresponding them to the laptop view.

4. Eventually you will star hop across the sky from star to star as both views match.

[bcfcciderhead]

Glad it's not just me then!, had the same problem last night, Found Andromeda but not M31...and you can see that with your eye!!

[Doc]

M31 is naked eye from a dark site.

[Perryellis]

I did the same thing last night but with a little more success (mainly because I have spottted some of the targets before through bincos)

What I did was to locate the far left star (technical term that)of Cassiopeia, which is the epsilon star I think, and see if I could see a pattern of other stars nearby through my binocs-which I could-a sort of arrow or sideways V shape of stars. Once I had found this star I found it much easier to locate the other four and the clusters nearby.

In my opinion I found NGC 457 the most impressive or the most noticable due to it looking very much like ET or johnny five from short circuit!!-also because I had never found it before.

A had read a lot of people commenting that the double cluster is more impressive but I did not think so, maybe becuase I could not see them both at once due to my eyepiece?

I also found Kembles casscade and M76 using the same technique. I was not expecting to find M76 but I was amazed when I did. It looked like a very faint,grey egg timer type shape. I then tried to look for NGC 7000 and hartleys comet from the oct edition of S@N but without success and until the clouds came in.

I also used the finder scope which came with the scope.I know what you mean though. i have just started using my scope and find it much,much harder star hoping because of the amount of extra stars you can see and because the brighter stars through binocs are not much brighter than the other stars through a scope! Stick with it though and Good luck!

[Xaviermarch]

Thanks for all the comments and suggestions. I think I need to make myself some overlay templates of what my scope can see and use it with my star atlas rather than relying entirely on the books and magazines to find objects.

Four moon diameters for the view through my scope is actually more than I expected - I wonder if I'm moving too far and going straight past the thing I am trying to find.

I have a red-dot finder but up to now I've found it far too bright even on its lowest setting and I have found it hard to get the hang of getting it centred in my view without practically lying on the ground! More practice needed I think - the suggestion about checking it in the daytime is a great idea.

Now I just need some decent weather again to give it a go!

[NGC 1502]

Hi Xaviermarch, you can calculate the approx true field of view with any eyepiece

by dividing the apparent fov of the EP by the magnification.

I assumed the 40mm EP is a 1.25" fitting Plossl with an apparent 45 deg field.

So, focal length of scope = 900, divide by 40 = 22.5x mag.

45/22.5 = 2 degrees or 4 moon diameters.

This gives a fair chance that your target will be somewhere in the fov when

you point the scope at hopefully the right bit of sky.

Yes, many RDFs don't go dim enough. A clubmate sorted mine by soldering a

resistor into the circuit.

With practice, finding objects this way does get easier, even if it seems hard

at first.

Good luck !! Ed.

[Xaviermarch]

Thanks Ed. This makes me think that I am probably pointing at the right thing, but just not seeing it with my untrained eyes.

Some people mention Telrads as an alternative to red dot finders. Would this be a better way of pointing my scope? I am reluctant to get a proper finderscope while I'm learning because I'm guessing I would just have the same problem as my scope in having too many stars show up and not really knowing where I am.

[NGC 1502]

Yes, the Telrad is deservedly popular. Many find the extra circles that it has, helps

them find stuff more easily. It also does go dim enough without any modification.

The only down side (other than having to buy it ! ) is that it is much larger and

heavier than most RDFs.

Another alternative is the Rigel Quickfinder (available from SGLs sponsor) is much

smaller and lighter than a Telrad, and also goes dim enough.

I only use RDFs now, having got used to them, I wouldn't use anything else,

although plenty of folks just love optical finders, it's a case of finding what suits

you best.

As I've already said, mine didn't go dim enough, but was modified by a clubmate

who soldered a resistor into the circuit.

HTH, Ed.

[Rusty Strings]

I encountered the same confusion with increased stars through an optical finder, a Telrad solved it for me, excellent piece of kit.