Hi all. Ive been up around 4 lately before work so Ive been outside looking at Jupiter with my 8" dob. Been abit dissapointed though. I thought that being closer and bigger than Saturn that Jupiter would be much larger in my scope. Also there's lots of glare comming off the disc so Im not seeing much detail just a line around the center of the planet but no redspot or any other details. Will the viewing become clearer in the next few months?
You should easily be able to see the remaining one of the equatorial bands with an 8" Dob. If you don't then that could be because the seeing is bad (not much magnification possible) or because the scope is out of collimation. The second band has gone "missing", and the GRS isn't as spectacular as in the early 90s for example. With a well-collimated 8" Dob you should be able to see finer details nevertheless, but it varies a lot with the conditions.
Jupiter will come into better view in a few months time. Right now it's -2.4mag and 38" wide, but in September it'll be -2.9mag and 50". It will also be up all night and therefore easier to observe.
Cheers
Steffen.
Last edited by Steffen; 02-06-2010 at 06:28 PM.
Reason: one day I'll learn how to type...
It could be poor seeing, poor collimation or both. What eyepieces are yo uusing? Is your collimation up to scratch? Also make sure the 3 primary mirror clips are not clamped down tight on your mirror as this introduces astigmatism and will ruin the views. Many GSo-type newts often have the clips too tight on the primary. Ideally you should leave a tiny gap betwen the clip and mirror surface, about the width of a business card. You can check by observing the diffraction pattern of a moderately bright star at high power, if it's triangular, you've got a pinched mirror. This can easily be solved by removing the mirror cell and loosening the clips (it helps to put a tick on the cell and tube beforehand so you'll get it easily back on).
You can try a moon filter or variable polarizing filter to cut the glare.
In truth, the "Great Red Spot" is now misleadingly named - the reality is more like the "Faint Fawn Spot" A blue filter will help to improve the view, but only a little bit.
I agree with pcg Hunter. Some nights i have gone out and been in awe of what I'm focused on, a night later id say "I swear that was better last night" Seeing conditions would be a part of your problem I'd say, as well as collimation... and eyepieces. I find its twice as clear after i clean my eyepieces. My eyepieces probably require the most maintenance out of all my stuff.
Have you taken it out yet? ..to dark skies i mean.
Seeing will definitely get better as Jupiter moves more overhead later in the year as you will be looking through less atmosphere and the planet will be closer to us. Another good means of locating the position of the GRS is within the program Jupiter 2 which is a free download from the internet. This will give you real time positioning of the GRS together with times and positions of all the Jovian moon transits.
Cheers
A blue filter will help to improve the view, but only a little bit.
