Inexperience disappointment?

[jamieren]

Finally packed up that behemoth of a 12" scope last night and went out of town to a darker site. The moon was nice, actually it was fairly dim in the early stages of the evening, 9 - 10 pm. I noted the "wavering" of somewhat poor seeing when viewing it at 150x mag. Once it was up a little further (perhaps this was my first mistake) I began the search for M51, the whirlpool galaxy. I thought in relation to M81/82 it was closer to the big dipper so it should be relatively easy to find, and at magnitude 8 similar in brightness. After 1/2 hour of scanning I saw nothing. I tried measuring distances in the star chart and approximating them thru the finderscope. I tried identifying 'secondary' (or unnamed) stars in the chart and using them as guide lines. I even tried wantonly searching with the 32 mm eyepiece in hopes it would intensify the light (this is how I first found M81&82). I thought to myself "Maybe it's too bright out tonight" and swung the scope towards M81/82, reasoning that I shouldn't be able to see them either. Wrong. Within 5 minutes (less, actually) I had them centered in the eyepiece. Who'd have thought that would ever disappoint me?!

A couple of theories... first, with the moon out (about 1/3 in shadow) I'm thinking dim items like galaxies are going to be far more difficult to see with the washout of the moon. Still that doesn't explain why I couldn't locate the whirlpool galaxy since it is reportedly mag 8, the same as M81/82. Second, what I saw last night was disappointingly on par with what I saw a couple of weeks ago in the 8"! (albeit under darker skies I admit). Last but not least I'm now having some problems with the crayford focuser on this scope. When I put the SW 10mm (+/- 12 oz.?) the focuser will drop at times with a "clunk" all the way in and I have to manually lift it out as I turn the focus knob. Of course as soon as I let it go it will fall in again. This adds up to an irritating operation of physically holding the sleeve under the eyepiece and having to tighten the setscrews to keep it in focus. Not enjoyable at all if I'm switching eyepieces back and forth. I know the crayford is reported to be a "premium" focuser, but the rack and pinion setup that came with the 8" never gave me a hint of trouble.

[narrowbandpaul]

first, make sure the 12" is properly collimated.

secondly to conduct a fair scientific test, make sure your final assesment of the scope comes under the same conditions. e.g a dark moonless sky (like we actually get those!), bear in mind the seeing becomes far worse at lower altitudes, so compare objects at similar altitudes.

Good luck

[blinky]

I would put it down to the moon washing everything out. The other night I was looking for the ring neb. Pretty sure the GoTO put it in the field of view but could not for the life of me see it, I put it down to Luna!

[Astronut]

At this time of year with the Plough under Polaris M51 is approx 10-15 degrees lower in altitude than M81 and M82. Also, although it has a similar magnitude it's light is spread out over a bigger area making it more difficult to see. Coupling all that with the Moon washing out the background makes it difficult to spot.

re. the focuser: there should be a friction/tension adjustment somewhere on it. Sounds like it's too loose. Is it a new 'scope? If so, I would have a word with the dealer.

[Astro_Baby]

If its a Sky-Watcher Crayford some of them ship rather loose. Fine for a light EP but can be way too loose for anything heavy. The Sky-Watcher Crayford has a tension screw in the base with a hex adjuster bolt. Try turning that in a small bit and see what happens.

[Ant]

The moon will wash out most galaxies.

You'll be able to see a mag 8 point source no worries, but an 8 mag extended object will be all but invisible.

A collimated scope will help - but leave it a few days till the moon is further away.

As for the focuser - I had a similar issue on my APO - you need to find the tension screw and tighten it a little.

Good Luck

Ant

[themos]

This may be stupid but I've had my secondary dew up quite often and that really messes things up.

[Doc]

Jamieren exactly what you explains happens to me alot.

I thought with a 16" dob it would be so easy to find stuff. Believe me it's not you still have difficulty finding stuff the only difference being when you do see it you are 80% sure you have it.

You will find the bigger the scope the more stars you see, which makes star hopping really difficult.

Another problem is light pollution and bad seeing. I hate it blocks so much out.

[MarkAndLeanne]

Jamieren,

Speaking as people that have had numerous scope & mount 'issues' since taking up this astronomy malarky a year ago, we can only say that as others have suggested, collimation is the key. Then perseverance!

We too experienced some disappointing nights, not understanding why the same kit as everyone else didn't do the same as everyone else. But having spent months sorting out all the niggles, we've just had three consecutive nights (two visual, one imaging) with the scope, resulting in a warm glowy feeling of success - plus our first decent images (M57, M15, and a lunar mosaic still to be processed).

Don't give in!

[John]

The moon will wash out most galaxies.

You'll be able to see a mag 8 point source no worries, but an 8 mag extended object will be all but invisible.

I think Ant's point above is extremely pertinent. The published magnitudes of objects are often not a good guide to being able to see them. For DSO's the magnitiude given is the integrated mag of the whole object - M81 and M82 are quite "tight" objects and therefore relatviely easy to find. M33 by contrast has a published magnitude of 5.7, brighter than M81 and M82 and yet, because it's a more extended object, it's often quite difficult to find. As Ant says, if there is any extraneous light in the sky (eg: light pollution, moonlight) it tends to "kill" extended objects more than more condensed ones.

John

[russ]

Don't loose heart Jamie.

M51 is a right royal pain in the bottom at the best of times. It looks like it should be easy, just pop down from that bright star in Ursa Major and job done. But alas no.

A/ too low in the sky

B/ it's surface brightness is poor

C/ the slightest interference (moon, high cloud, mist) and its very hard

D/ M81/M82 are not a good guide. They are easy, especially M82 and can be seen even on a rubbish night

Under really, really good skies M51 is easy in the 50mm finderscope. From my backgarden it's hard work in a 6" or 8" scope. I haven't tried with 12.5".

Russ

[jamieren]

I've heard from a certain past employer of mine that he believed "Caterpillar has the best people". After joining this group I would definitely dispute that position. Thanks for the ideas, Doc I see your point about the star hopping. Russ, I appreciate the honest breakdown (but still have trouble accepting it!). Astro_baby I will check the tension screw - that answered my question of where it was ..and geez, I'd suggest you invest in turtle necks, winter's gonna be cold in that top and I bet you'll find the guys have less trouble being distracted from your opinions by that avatar! Narrowband & Ant; I've collimated the scope twice with a laser. I can't seem to get the secondary quite perfect (gave up after 15 min, but I'd bet it's 90 - 95% towards perfect center). Also I thank the couple who pointed out the altitude issue especially. That's something I didn't yet know. Themos: dew is not the problem this time (but I'll be sure to verify that!), and I get the feeling that may be a good tip for the near future. I keep hearing 'don't give up' and usually it is unnecessary, but the other night I found out exactly how quickly one can feel like doing just that in an uneventful couple of hours.

[kev1204]

Hi

I know just how jamieren feels.

Ive been observing since I bought a skywatcher 130pm 9 months ago, and several times I thought about packing it in. I've only had maybe 2 nights out of approx 30 when the seeing has been good enough to spot any DSO's. Both times I managed to spot several galaxies in Ursa major and Cannes Venatici, otherwise its been very disheartening especially after setting up the scope and collimating etc to find myself once again looking at M31 and M57 as no other DSO's were visible.

I bought myself a 12" skywatcher flexi Dob last week and have found that although I can definitly tell if the object is a galaxy ( rather than just another star as with the 130 newt as Doc has stated above) some objects I just cannot find even though I check collimation at every set up.

I can only put this down to Light pollution and atmospherics.

At times astronomy can feel a very frustrating hobby, only alleviated by the joy of seeing something different.

I guess its gonna be a long road!

[FLO]

What telescope is it?

[Talitha]

Might this help anyone? ARVAL Catalog of Bright Objects

Light pollution and poor transparency will no doubt gobble up most everything except the open clusters, but maybe not.. you don't know till you try.

They supply the magnitude, size and area of objects but not the surface brightness. Not a problem.. you'll quickly get the hang of guesstimating it by balancing the magnitude and area.

Most lists don't include the area like this one does though, but that doesn't matter either. After a while you'll be able to look at a list and see an object's magnitude and size, and automatically determine whether it'll be do-able or not.

Btw, for those who might not be familiar with the concept of surface brightness, it's merely a balance of brightness versus size.

Think of a piece of black paper with a drop of glow-in-the-dark paint on it. Turn the lights off and the drop is pretty easy to see, but if you spread it out a bit it gets dimmer. Spread it out even more and it gets even dimmer.

[FLO]

What telescope is it?

It wasn't a loaded question

It's just that I am wondering whether collimation is behind your disappointing first-light. If your Dobsonian is based on the GSO mirror cell then I was going to suggest contacting Bob's Knobs for a set of replacement springs (the original set can sag from the weight of the mirror so it can be difficult to set and maintain accurate collimation). Details HERE.

HTH

[Casus belli]

M51 is easily visible in a 10" dob......on a moonless night...if your eyes are light adapted..if light pollution isnt bad. Altitude of galaxy can make a huge differance too.

I use the beehive cluster as a guide during winter months. If I can see it naked eye then its galaxy hunting time.

What size of eye-piece are you using? If Im using a 2" ep I dont put it all the way in as I cant get proper focus. The 1.25's are ok