Helix and the like

[PSALM19.1]

Hi,

Just wondering, what am I looking for when trying to find planetary nebula (like Helix for eg)? Using an 8" Dob and finding it hard to find! Does anyone have a sketch or even a shot of what I might see through the eyepiece? I haven't been trying to find any planetary's as yet but have read they can look pretty good at times....thanks all :)!

[BeanerSA]

Try googling for "helix nebula sketch" and then looking in Images.

[julianh72]

I think "Turn Left at Orion" is a great handbook which will help you get an appreciation of what you are looking for. There is a companion web site, which has sketches of many of the main targets, including the Helix Nebula, which has sketches for an 8" SCT and a 4" Newt:
http://www.cambridge.org/features/turnleft/pages/seasonal_skies/oct-dec/in_aquarius_the_helix_a_planetary_n ebula_NGC_7293.htm

The sketches are generally negatives (dark stars on a white background) as this is generally easier to interpret. The sketches for an 8" scope typically assume you have good viewing conditions; if you suffer from a bit of light pollution, the 4" views might be more representative of what you'll see at first glance, especially if you haven't got fully dark-adapted vision etc.

I have inverted the sketches for the 8" and 4" views and attached them - as you can see, the Helix probably won't "knock your socks off" unless you have reasonably good viewing conditions.

[barx1963]

Shaun
The Helix Neb (technically NGC 7293) is fairly large and has moderately low surface brightness. It also is a late riser at this time of year, being only 11deg above the horizon at the moment. At midnight it will be about 35 deg up so will be easier. An 8" should see an oval haze, it is quite large (unlike most PNs) so low power is best at first. Because of the dark centre, it will appear as a sort of ring. If conditions are good and you have a dark sky, the mag 13.5 central star may be getable also.
Some other good PNs to have a crack at are NGC 6302 (the bug nebula in Scorpius), NGC 3918 (the Blue Planetary in Centaurus) which is the brightest of the "southern" PNs, and M57 ( the Ring Nebula or NGC 6720 in Lyra) which is low in the North culminating about midnight.
All three of these exhibit differences in structure and colour which make them interesting objects to start your PN adventure.

Malcolm

[PSALM19.1]

Awesome, thanks all! So colour is possible in my 8" for Planetary's?

[The_bluester]

At the very least I would expect the blue planetary to show colour, it is obviously blue in my C925.

[barx1963]

Shaun
Sorry I haven't replied earlier. Some PNs will show colour. As Paul has said NGC 3918 is very distinct. The larger ones (NGC 7293 the Helix for example) usually do not. An interesting one is IC418 (sadly not visible ATM but once Lepus comes back to our skies, check it out) as it displays distinct red/orange colours in my old 12" so worth trying in an 8"

Malcolm