M108 & M97

[8472]

Hi guys,

Having trouble locating the above objects.

I'm pretty sure I'm pointing in the right direction, but I just can't seem to see nowt in my Dob.

I gather both of these are relatively faint objects, but what kind of eyepiece Mag. do you suggest I use (out of what I have)?

I suppose I'm not helping myself by trying to view to low in the horizon (circa 25 degrees altitude) but surely I should see something?

Cheers,

Kev.

[Guest Eddy]

Never seen either myself but M108 being 10.7 magnitude and M97 being 9.9 you will struggle without really good skies.

Put it this way, M51 is 8.4 magnitude and only just visible last week in Craig's 10" and when I say only just, averted vision was needed just to make out it was there.

Hope this helps.

[Tweedledee]

These two can be really difficult.

Definitely try for them when they are nearer the zenith and you are looking through less thickness of atmosphere, therefore not dimmed by the atmosphere, say after 3am at this time of year.

You can check with detailed star maps or Stellarium that you are in exactly the right region as these objects won't readily show just by panning around. Even print off a couple of Stellarium views at different scales and get the orientation correct (inverted). Try to familiarise yourself with the pattern of stars (usually fainter than naked eye) in the area of a couple of degrees of the objects and their geometry and relationship to the objects. There are several stars between 6th to 8th mag that will help in the vicinity of these two and be visible in the finder.

They should both be in the same field of view in your eps of 20mm or longer focal length. Sometimes a slightly higher magnification can increase the contrast and just darken the sky background enough for the objects to appear but that will mean a smaller field of view so you really need to be close. So try different eps but not too high a power.

Your eyes need to be really well dark adapted to see such extended 10 and 11th magnitude objects. It can be very helpful to use a cloth or towel over your head to totally exclude any other light, not just street lamps, even brighter stars or planets. Sometimes you have to look for a while without taking your eye away and let the image imprint itself. Averted vision can also be good. Look slightly away from where you know the object should be, but concentrate on where you expect it to be. Google averted vision and you should find some good info with drawings on how best to do it, it is a useful technique to learn to find faint extended objects. Sometimes jiggling the scope a very small amount can help you perceive a very faint object.

A broadband light pollution filter might help but I doubt it will do much more than just dim everything. A narrowband OIII filter might help with M97 but will completely kill the galaxy M108 and dim the stars around it.

The very slightest amount of dew on any of the optics will completely render these things invisible while you will still see the stars pretty well.

Sometimes none of the above will help, yet on another night under different conditions they may be more readily visible.

Just a few ideas there.

Edited November 18, 2012 by petersull

[Doc]

You are way to low into the murky skies, I doubt very much you will see them.

Wait till UMa gets to at least 30° and they are actually not that hard when the seeing is correct.

I always used to locate the position with my 28mm, then swap to my 16mm for a closer look, and if I was adventerous I go in with the 7mm to have a real good peek.

Just keep trying and eventually they will pop out.

[8472]

Some welcome words of wisdom there to take onboard.

I guess i'll either have to stay up late, or get up early for some nearer zenith observing then. I'll try my 20mm or maybe my 32mm, to locate.

The upside being most of my neighbours will be tucked up in bed with the lights off, too.

Eyepiece filters look a virtual minefield, of which I've yet to dabble in, tbh...

Cheers!