Little Desert - 29/12/10 - Dark Dark Skys !

jamespierce (James) · #1 30-12-2010, 09:54 AM

Little Desert Nature Lodge - Night 1:

All viewed through my SDM 16" plus quite a few sneak peaks through skyoyster's Tak which was set up beside it at the Little Desert Nature Lodge. I used the 21mm Ethos 99% of the time, switching to the 10mm to take a closer look at a handful of objects.

We set up a little way away from the lodge at twilight, watching the clouds and bugs clear to a perfect night. I had a few Servocat issues early on, because of the heat I think??? The cable tension was just a little too low to pull the scope up, especially with a Paracorr and a heavy eye piece in. With some fiddling it got better but the tension adjustment is already against the end of its thread so I either need to swap for a slightly shorter cable, or for this trip just stick something small under the cable at the far end to make it slightly tighter. At this point it was warm, ambient of 26 degrees and the mirror still stubbornly at 31.

Once the Argo and Servocat were sorted and we waited for it to get really dark, I chased down a bunch of northerly Messiers, including a couple of new ones for me, M1, M35, M36, M37 and M38 plus a slew of old favourites. The temperature dropped quite quickly, but the mirror still couldn't keep up, about 4 degrees above ambient.

As it hit astronomical twilight, the scope was pointed towards Orion so I started to work through a bunch of the nebulae and clusters in this region of the sky (Orion and Canis Major). I ended up at the Flame Nebula which is nice, but once I was there the temptation to try and see the Horsehead took over. It's hard to truly resolve, but I could definitely see the dent, and some shape around the neck with UHC and Hb (Hb is better). I'll have to come back and try this again when I've not been futzing with red lights and looking at charts etc. At this point the air temperature was below 20 and the wind had picked up, after a 35+ degree day in the desert it seemed somewhat ridiculous to go and get a down jacket, beanie and gloves (but I did).

Having returned with more warm clothes I started a detailed look at the LMC, there are so many objects here that the Argo and Servocat stopped being very useful except for tracking the scope. Our normal viewing site has pretty dark skies everywhere except south, where it picks up quite a bit of sky glow from the town so it was a treat to enjoy this area of the sky in detail. I swung over for a quick look at 47 Tuc and the SMC. By now the ambient was 14 degrees and my primary mirror 3 degrees below that in spite of all the fan's running - still didn't need dew heaters all night so we can't complain really.

I finished off the night dancing across the sky to Fornax viewing perhaps 30 galaxies with a couple of nice barred spirals as a highlight, it seems like you can't help but have 3 and 4 galaxies in the eye piece at once most of the time in this region. At about 2:00am a small waning moon rose with Saturn at its side and we packed up calling it a night.

Some particular Favourites and Highlights

* M45 seeing nebulosity around all the main stars, improved by a UHC filter.
* M46 and the planetary NGC2438, the planetary really stands out with an OIII filter.
* M35 a bright open cluster with the small and tighter NCG2158 near by.
* The galactic cluster in Fornax, in particular the beautiful barred spiral NCG1365 - can't help but think of Rodstar waxing lyrical about Zorro every time I see this one now.
* The LMC - I enjoy hopping around the whole thing but wow, at a true dark site the Tarantula is something else eh - I love how it shows three distinctly different sets of detail with no filter, a UHC filter and an OIII filter.
* Seeing the Horsehead Nebula for the first time - in my 16" it was straight forward to see with a UHC filter and almost enjoyable with the Hb filter.

We have another night here at the Little Desert tonight and then a few more in the Grampians on our way home - hopefully this clear weather holds out, with the moon up later tonight we might stay up late enough to see Saturn get up high enough to try and see the current storm.

ngcles · #2 30-12-2010, 10:42 AM

Hi James & All,

Thanks very much for posting your observations James -- much enjoyed.

A UHC filter shouldn't be of assistance with the nebulosity surrounding the Pleiades. It is a reflection nebula and has the same basic colour as the stars themselves. It has no emission component because the stars in the cluster don't put out enough high-energy U.V light to ionise Hydrogen (You need O3 to O9 stars to do that sort of thing). A UHC filter blocks starlight and in doing so blocks reflection nebulosity. Go without filter !

You mention the cluster next to M35 -- I think this is a typo as it is NGC 2158. A distant (but quite large) open cluster that is somewhat reddened compared to M35. Believed to be a G.C up until about the 1970s when someone did a C-M diagram that showed it's decidedly "open" character.

M46 and its embedded planetary (NGC 2438) are excellent. The planetary would be an excellent target by itself.

"Zorro ..." yes, very apt moniker. I won't be able to get the theme music for Zorro out of my head now for the rest of the day!

Hoping for continued clear skies. I'm aiming to get out to my "nearly dark" site tonight.

Best,

Les D

jamespierce (James) · #3 30-12-2010, 10:52 AM

A UHC filter shouldn't be of assistance with the nebulosity surrounding the Pleiades. It is a reflection nebula and has the same basic colour as the stars themselves. It has no emission component because the stars in the cluster don't put out enough high-energy U.V light to ionise Hydrogen (You need O3 to O9 stars to do that sort of thing). A UHC filter blocks starlight and in doing so blocks reflection nebulosity. Go without filter !

I've observed M45 a couple of times looking specifically at the nebulosity, I can see it clearly both with and without the filter, both time's I've thought it was a little more obvious with the filter - perhaps it's just a placebo of a slightly darky image overall ? I will look again with more care tonight !

You mention the cluster next to M35 -- I think this is a typo as it is NGC 2158. A distant (but quite large) open cluster that is somewhat reddened compared to M35. Believed to be a G.C up until about the 1970s when someone did a C-M diagram that showed it's decidedly "open" character.

Yup, typo (fixed) - it's beautiful though isn't it - it almost does look like a G.C.

M46 and its embedded planetary (NGC 2438) are excellent. The planetary would be an excellent target by itself.

Yup, with a bit of magnification and the OIII the cluster fades and the planetary really pops out. Very easy to find planetary for anyone wanting to find their first too.

Rodstar (Rod) · #4 30-12-2010, 03:00 PM

Hi James (and hi Alexandra!!),

Sounds like you are having a wonderful time down there, albeit with a few thermal and cable tension issues. Hope conditions are again dew free for you tonight.

We must be cosmically aligned, because I was out in the backyard last night enjoying many of the same views as you (with the unfortunate addition of a heavy seasoning of suburban light), with the assistance of my new Cambridge Star Atlas (

thanks mate - decided to keep it, it is SO good!).

It had been a while since I had done any observing, so I went through a series of familiar favourites, enjoying the beauty and wonder of M42, the gargantuan Tarantula Nebula (still replete with Christmas ribbons) and surrounding host of angelic shapes of the LMC, the diamond pin cushion that is 47 Tuc, the wispy mystery of the Pleiades, the royal engagement ring that is NGC 1535, and the ghostly orange sapphire that is IC 418.

My old favourite M79, a nice globular in Lepus is still there, humbly doing its own thing, and M46, what a treat, with her little foreground planetary teased me with some detail in its outer shell.

James, I tried in vain to snare some detail in some of the Fornax galaxies, but there was a constant passage of clouds meandering through the sky on the central coast, reflecting all of that ambient light and washing out any detail. I will have to wait for some darker skies to enjoy such deep skies wonders.

I also have no chance of seeing the Horsehead under suburban conditions. You are doing well to see it with a 16" scope, it is one very elusive target! I have to work very hard to see it under dark skies with 20".

If you enjoyed M46, you might like to try NGC 2818 in Pyxis, which is a more subtle version of M46, with planetary.

There are so many beautiful doubles in Orion and Canis Major. Don't miss out on Sigma Orionis or Adhara (epsilon Canis Majorum).

Clear skies!

jamespierce (James) · #5 30-12-2010, 04:25 PM

Quote:

Originally Posted by Rodstar

James, I tried in vain to snare some detail in some of the Fornax galaxies, but there was a constant passage of clouds meandering through the sky on the central coast, reflecting all of that ambient light and washing out any detail. I will have to wait for some darker skies to enjoy such deep skies wonders.

I also have no chance of seeing the Horsehead under suburban conditions. You are doing well to see it with a 16" scope, it is one very elusive target! I have to work very hard to see it under dark skies with 20".

It's really dark out here, not the inkiest I've ever seen but close - Makes me inspired to get out here for the Vic South Star Party (Astro Society of Vic's Big Bash) - significantly darker than Loststock. It's clear again tonight too - night 2 of hopefully 6 for this trip. We are in the same boat as you, between weather and life we've only really been out 2 or 3 times seriously since IISC - last night was play time, tonight I'll be more diligent about working through some constellations like Fornax before they disappear etc. You've just added a few things to my 'must see' list - keep em coming !

Oh BTW, when Peter put on the Argo (on the way home from IISC), he insisted on doing a Servocat too - this thing is cool as - The GOTO is neat of course, but it's just as quick and easy to PUSH-TO ... But, especially on the really faint stuff it makes a huge difference having the tracking, you can really just focus on viewing - or changing eye pieces or checking a chart etc without ever loosing your place, it's a real asset looking at something large and complicated like the LMC also.

Oh yeah, I just found AstroPlanner too today - seems like it would be right up your alley - well worth a look, can build custom Argo Navis catalogs.

pgc hunter · #6 30-12-2010, 04:57 PM

Cool report James. Enjoyed it thanks for posting.

That's one issue with desert climates, the temp drops like a brick at night. Take a look at Mildura, 26C at midnight last night, by dawn down to 17C! Active cooling is definately the answer in such conditions and even then a decent thickness mirror would struggle to keep up. Excellent period of clear skies in the northern half of Vic lately though, hopefully it'll continue.

Rod - interesting you see IC 418 as orange, I've tried in vain to see the reddish colour reported numerous times. Never was sure if it's aperture or skies that are more important.

skyoyster (Alexandra) · #7 30-12-2010, 07:55 PM

I had as much fun as James last night, looking at quite different things! I have a perhaps tediously extensive observation report over at my blog, but highlights:
* M42 and 43, of course - I really do love this time of year - they just looked incredible. Every time I look at the nebula there it just looks brilliant.
* an awesome little planetary, NGC2438, and a totally lovely open cluster, NGC2169.
* various double stars
* Omega Centauri (always breathtaking, and stupidly detailed);
* the Gem Cluster and Jewel Box (open clusters I will make an exception for);
* Centaurus A (a faint galaxy with what appears to be a split in the middle);
* and the seriously cool Ghost of Jupiter (another planetary nebula - I love it).

Plus everything James insisted on showing me...

We packed it in around 2.15, with the moon rising: a crescent, it was so yellow it looked like a banana. If we'd hung around a bit longer we could have looked at Saturn, but my goodness it got cold. From complaining about the heat in the day, we ended up as rugged up as we've ever been while observing. Can't wait for tonight.

Rodstar (Rod) · #8 31-12-2010, 12:56 PM

Hi guys,

James, I am very jealous re the servocat. Yes, one day I will get one, it is all a matter of financial priorities.....I am burning a very large hole in my pocket with a trip to France in 2011, and so I just cannot do it at the moment. I would agree that having tracking adds to the capacity to focus on an object, as does being able to sit down, rather than strain on a ladder. I am torn, when I do have the spare cash, as to whether I will prioritise getting the servocat, or getting a faster mirror for the scope (such as f/3.7) or getting Peter Read to make a folded design for my scope (making it possible to sit to observe).

pgc - I first saw IC418 through a 25 inch scope, and it was a deep orange colour. Since then, whenever I have observed it, I have seen a white central star with a core halo of mid to dark orange, and a secondary halo which is grey-white. It helps with the extra aperture. On nights of poor seeing, the colour is far less distinct, indeed, the entire halo could be generally described as drab grey!

Alex - nice write up on your blog (love your website BTW!). That Tak of yours must be awesome for tight doubles. Next time I see you guys I would like to spend some proper time seeing what the Tak can do!

Hope your third night is worthy of New Years Eve. Happy new year!

jamespierce (James) · #9 31-12-2010, 01:36 PM

Quote:

Originally Posted by Rodstar

I am very jealous re the servocat. Yes, one day I will get one, it is all a matter of financial priorities.....I am burning a very large hole in my pocket with a trip to France in 2011, and so I just cannot do it at the moment. I would agree that having tracking adds to the capacity to focus on an object, as does being able to sit down, rather than strain on a ladder. I am torn, when I do have the spare cash, as to whether I will prioritise getting the servocat, or getting a faster mirror for the scope (such as f/3.7) or getting Peter Read to make a folded design for my scope (making it possible to sit to observe).

Tricky decision - A new mirror isn't going to come cheap, mind you I would expect you could get more than half what your current mirror is worth back. I'm a bit on the fence about the folded designs, seems like more fiddle, more setup, more points for flexture and collimation issues etc. Much larger secondary obstruction too, which isn't going to be so much an issue for pure light grasp, but would knock a bit off the resolution I think.

Perhaps do the Servocat first and see how that improves the ladder ergonomics - I think fast mirrors are only going to get faster, cheaper and better over the next few years as more makers start doing them. I assume having your current mirror reground is a crazy suggestion ? Would Mark do it ?

A 20 F3.7 mirror would make the rose about the same height as my scope, cool huh !

pgc hunter · #10 31-12-2010, 02:31 PM

Quote:

Originally Posted by Rodstar

Hi guys,

pgc - I first saw IC418 through a 25 inch scope, and it was a deep orange colour. Since then, whenever I have observed it, I have seen a white central star with a core halo of mid to dark orange, and a secondary halo which is grey-white. It helps with the extra aperture. On nights of poor seeing, the colour is far less distinct, indeed, the entire halo could be generally described as drab grey!

That sounds like an impressive sight. I always see it as whitish/grey. But I just love its super-bright rock hard disk. Might need some darker skies and good seeing to catch its ruddy hues.

Paddy (Patrick) · #11 01-01-2011, 12:01 PM

Sounds like a great night James. Nothing like dark skies and a big scope.

If you want to find your way around the LMC, I have just finished the charts for it at my web site cloudsofmagellan.net.au . You can download PDFs with 470 LMC objects marked on DSS images.