Report: Herschel galaxies in Ursa Major, Virgo, Draco

[acey]

A Friday night with no cloud and no moon – a rare thing indeed. Determined to make the most of it, I loaded my Orion Skyquest 8-inch dob into the car along with some Televue Plossls (32mm, 20mm, 8mm), my usual charts and references (Uranometria, Sky Atlas 2000.0, Strong and Sinnott’s Sky Atlas Companion, Luginbuhl and Skiff’s Observing Handbook), and headed out to add a few more ticks to my Herschel objects project. By 11pm I was ready to start.

Under mag-6 skies, the only irritation was a cold wind and a large amount of bovine poo deposited by earlier site users. A quick peek at Saturn showed seeing to be quite good: the planet’s banding showed up nicely. Then a look at M51, admiring the variations in brightness in the main galaxy disc while my eyes became properly dark-adapted. The twinkling, brighter inner regions and fainter enveloping halo, especially when seen with averted vision, give a definite sense of the spiral structure.

Then to business, and first off was a galaxy I’d searched for under poor skies last week before giving up empty handed. This time, NGC6412 (Draco) showed up, though small and faint, seen only with averted vision at x150. Herschel miscatalogued this as a planetary nebula: there’s a faint star just west of the galaxy that pops into view with direct vision, giving the overall impression of a star with surrounding nebulosity, hence – I assume – the great man’s mistake.

Another Draco galaxy, NGC5678, was tricky to manouevre to, being high overhead – not the best place to try and aim a dob, especially with a straight-through finder that forces you to get down on your knees. The upside is better transparency: most of the night’s crop were to be objects in this neck-cricking neck of the woods. I found 5678 to be quite bright, moderately large, seen to be elongated at x150, possibly mottled, gradually brighter towards the centre, with perhaps a stellar core seen in averted vision.

Next a quick look at M101, since I was in the neighbourhood. A few years ago I found this a difficult object: now it’s the sort of thing that looks eye-poppingly bright. Take my other remarks with that cautionary note in mind.

NGC5631 (Ursa Ma) was easy at all magnifications, packing 11.5 magnitude into a small, round surface area, most of the light being in a tiny circular core region with a stellar nucleus. This object is in the Herschel 400 and deserves its place there.

More Ursa Major galaxies: 5585 proved to be quite large and faint; at x37.5, a faint, even glow seen with averted vision; x150 showed possible elongation, roughly SW-NE, with occasional hints of twinkling over the surface. At reported mag 10.7 this sounds brighter than 5631, but the larger area and uniform surface brightness makes it a lot harder to see.

A Great Bear trio next: 5376, 5379, 5389. -76 was easy at x37.5; x60 showed a bright inner region with fainter halo; x150 showed much elongation E-W, fairly even brightness, but gradually brighter to centre, no stellar core but possible mottling. Herschel mistakenly catalogued this object twice: both in his Class I of bright nebulae, and in his Class II of faint ones. Must have been a bad night when he made it a II, it’s an easy object in the 8-inch. Nearby -89 is moderately bright, seen at all magnifications with direct vision, very much elongated, with a bright, almost stellar core. Its partner -79 is much fainter, elongated, even in surface brightness, seen only with averted vision. All three galaxies form an interacting group, and fit in the same low-power field.

By now it was 1.30 a.m. and time for a break, after which I decided to aim the scope lower, to take in some Virgo galaxies. I was immediately reminded of the poorer transparency as you get away from the zenith: I searched for NGC 4941 in Virgo and couldn’t confirm it. Another Virgo galaxy, 4731, was barely glimpsed at x60 with averted vision as a large, soft glow.

Not feeling like a challenge when I was already so tired, I tilted higher again, and found nice targets in NGCs 3665 and 3658 (Ursa Major). My log showed a previous observation of 3665, and I tried to remember which list it must be on. The brightness of 3665 made me wonder if it might be a Caldwell – it was my brightest non-Messier object of the night. Actually it’s in the Herschel 400, and when I looked this morning at my earlier notes I found that back in 2005 I called 3665 “not particularly bright or prominent”. Another indication of how my standards have changed. Now I’ve recorded it as round, bright, with a very bright inner region, possibly mottled, possibly with a stellar core, overall resembling an unresolved globular cluster. Nearby 3658 (in same low-power field) is much smaller and fainter: easily missed if you’re only bagging objects on the Herschel 400 list. x150 showed 3658 to be much elongated (approx. N-S) with a slightly brighter inner region and a stellar core.

Lastly I used my Uranometria to hop over to NGC3813: moderately bright, moderately large, much elongated EW at x150, a brighter inner region within a fainter halo.

That took me past 3a.m., and with the wind picking up and patchy clouds appearing, I reckoned it was time to call it a night. Like most scope users, I get regular attacks of aperture envy: last night’s session reminded me just how much mileage you can get out of an 8-inch, if you give it time and patience.

Andrew

[Sam]

Great report Andrew. I must have a go at some of the targets you are getting. It's so awesome viewing galaxies and once the eyes are fully dark adapted its quite staggering the amount of detail that becomes visible. I must give M101 another look as I can't remember what it was like last time I looked. A very nice detailed report and thanks for posting it.

Sam

[jgs001]

Great report and a good read Andrew, thanks

[Stephen Green]

A reat report Andrew I realy enjoyed

Stephen

[Casus belli]

Excellent report. You really like your obscure galaxies don't you? I didn't even know that any of these even existed. I've just found them on Cartes du Ciel.

I take it that this was a proper dark sky site. If so I'm even more determined to get my scope out to the wilds.

One last question. Does the close proximity of bovine poo help with seeing conditions?

Please keep the reports coming. If I cant get out observing myself then reading other star gazers reports is almost as good.

[Sam]

One last question. Does the close proximity of bovine poo help with seeing conditions?

...it'd keep your feet warm! :lol:

[acey]

Good idea - I must try making a poo stove! (Though I suppose all that smoke would get in the way).

I'd rate my site as adequate but not brilliant - there's significant light pollution on the south-east horizon but overhead it gets down to magnitude 6. It's a case of balancing how far you're prepared to drive against how much you'll see when you get there. (I started another thread on "site rating" here).

I hadn't actually heard of Cartes du Ciel - I should look that one up. For the last few years I used Sky Atlas 2000.0, then recently got Uranometria which is great - I can star-hop with the main telescope at low power.

Glad you liked the report - I hope to put up more as my Herschel quest continues. Let's hope for more dark skies before end of season!

Andrew

[Plastic chicken]

Eyepoppingly bright!!! M101!! I`ve only ever seen it once tbh can`t recall what size scope it was through. I`ve now got a 16" LB and i`ve yet to find it!!! Don`t have bad skies, about mag 5 on a good night. Where are you located just out of interest?

PC

[acey]

Hi PC - I do my observing from rural sites in Northumbria with mag 6 skies, but M101 can be a challenge if transparency is lower. A couple of weeks after my report above, I viewed it again from the same site but in poorer conditions with a transparency of around 5, and I could still see it, but it was a poor sight (as was M51).

And like you, it took me a while to find M101 initially. It's an easy enough star-hop, but you need to make sure you've got a low enough power to handle its large size and low surface brightness, yet high enough to darken the sky background. Large aperture binos (eg 70mm) or a rich-field scope (eg an 80mm Startravel) can do the trick. On a good night, compared to many of the galaxies I look at, it is indeed eye-popping!

I've never checked to see exactly how faint I've been able to go in the objects I've observed with the 8-inch, but a couple of years ago I was able to see most of Stephan's Quintet, and they're around 13, I think. I do envy you that 16-inch, though!