Observation Report 12/6/11

[shelltree (Shelley)]

NGC6322 in Scorpius

A strange triangular open cluster of stars with a clump of stars seemingly wrapped in nebulosity at its centre. Below this are two bright golden stars. I found this while searching for NGC6193, an open cluster in Ara. I managed to find NGC6193 as well, a small cluster of white stars, like jewels in the sky.

NGC6397

A faint looking globular cluster in Ara, east of the double star, in the same FOV with binoculars. Dense and fuzzy but very exciting to find!

47 Tuc

Using one of the bright stars in Hydra, I made a triangle with stars in Tucana and easily found 47 Tuc. Dense and dim under an 86.2% waxing gibbous but easily discernible. A very exciting find as I used the planisphere and tracked out the constellations in the sky without assistance.

M13 (NGC6205)

The Great Cluster in Hercules was very faint through binoculars, a very dim fuzzy patch, with sometimes discernible stars horizontally on either side.

M6 Butterfly Cluster

Beautiful and bright, visible naked eye even under a waxing gibbous. Very sparkly and condensed, with clear patterns of stars jumping out at me from the binoculars. The Butterfly Cluster is aptly named and also reminds me of an "X" marking the spot of an amazing treasure in the sky.

M8 Lagoon Nebula/M20 (NGC6514) Trifid Nebula

Very faint nebulosity, mainly in M8 but still easy enough to find, even with the moon so bright. The Lagoon Nebula seemed long and narrow surrounded by dim, greyish dust and gas.

Omega Centauri

Bright as usual though slightly fainter, its form seemingly grey and cloudy due to the waxing moon. Almost impossible to see naked eye without scrutiny.

Spica

Appearing very blue and vibrant, even in the glare of the moon. Uncertain whether the bright moon could effect its apparent colour or whether the seeing was just very good (despite the moon).



Corona Borealis

The Northern Crown was fainter than the view of it under dark skies but still reasonably easy to find once I knew where to look. Its brightest star, Alphekka, was like a blue jewel atop a crown, hanging in the shadow of Bootes.

Southern Pleiades (IC2602)

An absolute highlight of the night. So bright and brilliant! A cluster of twinkling jewels, seemingly hanging in the sky, with a few brighter white stars near its core.

Cen Nebula (IC2944)

Clear nebulosity in the centre, seemingly surrounded by bright stars on either side, like arms. Reminds me of the dense parts of The Milky Way, a breathtaking sight.

Cru Cluster (NGC4755) Jewel Box Cluster

Small but still very bright, almost in a triangular pattern.

Brocchi's Cluster (The Coathanger)

Easily discernible after Jason helped me find it! Very bright with crisp stars, especially magnificent through 11x70's. Now renamed Altair's Coathanger!

NGC3766

Fairly dim collection of stars in Centaurus but very pretty nonetheless.

Musca

Was easily found underneath Crux, with two bright stars close together, a definite give away of this particular constellation.

Pavo

Harder to find but eventually found "Peacock" above the tree line which also helped me find Idus beneath. Triangulum Australe consisting of three brighter stars was easily found using "The Pointers" in Centaurus as a guide.

All in all, an amazing night observing with Jason! I was so proud that we found so many objects and familiarised myself with the constellations more!

[pgc hunter]

Great observations Shelltree. Loved your Omega Cen vs M13 obs. There are about 6 globs in the southern hemisphere that trump M13. Nice job sighting IC 2944/Running Chicken Nebula..... this object is generally quite faint and a challenge from suburban skies. I've never observed it from truly dark skies, only from suburban Melb..I'd imagine it to be a rewarding target away from city lights. Also try for Ced 122 on the eastern side of the Coal sack.

[michaellxv (Michael)]

Great report Shelley, a nice selection of targets a very enjoyable read.

[ngcles]

Hi Shelley,

You are certainly right about IC 2602 -- it is one of the very best open clusters for binoculars. It is interesting that you noted Spica's colour but didn't see colour in any of the stars in IC 2602 -- which are about as blue as they can be to our vision. There are three stars in the cluster with B-V values that are "more blue" than -0.13 -- the same as Spica. Theta itself is -0.20 (which is exceptionally blue).

I guess maybe the difference is brightness and the brighter star has more capability to saturate your colour receptors.

Take a look again -- see what you think.


Best,

Les D

[shelltree (Shelley)]

Originally Posted by pgc hunter

Great observations Shelltree. Loved your Omega Cen vs M13 obs. There are about 6 globs in the southern hemisphere that trump M13. Nice job sighting IC 2944/Running Chicken Nebula..... this object is generally quite faint and a challenge from suburban skies. I've never observed it from truly dark skies, only from suburban Melb..I'd imagine it to be a rewarding target away from city lights. Also try for Ced 122 on the eastern side of the Coal sack.

I'm about 45 mins from the city so I have darker skies than most suburban homes but still isn't great. Maybe I was seeing something else but I certainly thought it was IC2944

And I'll have to try for Ced 122 next time I'm out

Originally Posted by michaellxv

Great report Shelley, a nice selection of targets a very enjoyable read.

Thanks Michael

Originally Posted by ngcles

Hi Shelley,

You are certainly right about IC 2602 -- it is one of the very best open clusters for binoculars. It is interesting that you noted Spica's colour but didn't see colour in any of the stars in IC 2602 -- which are about as blue as they can be to our vision. There are three stars in the cluster with B-V values that are "more blue" than -0.13 -- the same as Spica. Theta itself is -0.20 (which is exceptionally blue).

I guess maybe the difference is brightness and the brighter star has more capability to saturate your colour receptors.

Take a look again -- see what you think.


Best,

Les D

I have a feeling I did notice the blue of the stars in the Southern Pleiades but I was generally so awe struck by how bright and brilliant it was that I didn't note it. I also wrote my report later on and was very tired and probably forgot to add that in Next time I'm thinking I'll voice record it so I can go back to it later

[Paddy (Patrick)]

Great report Shelley I really enjoyed your descriptions. Haven't had a look at NGC 6322 - sounds an interesting one.

[shelltree (Shelley)]

Cheers Patrick! It was actually a real stunner, I have to say. Can't believe I haven't seen it before!

[Suzy]

Terrific report Shell!
I missed reading your reports.

Boy or boy you are giving those new binos a great work out, so amazing the ton of goodies that can be seen through them!

That beautifully described cluster, NGC 6322 has got me intrigued so I've put in on my to do list for next time. I often visit NGC 6132 in the table of Scorpio and scan the surrounds - can't believe I missed that one being so close to it.

Regarding the Lagoon nebula, thru binos I was surprised by the length of it and how bright it actually was. Nearly blew me over. I loved your description of it. When I viewed it thru my binos, it was quite high (about 60 deg) and the sky was nice and clear. So keep trying on that one without the moon in the way, it will be worth it as it does get brighter and you'll make out the bright star cluster embedded in it. It's pure awesomeness. That actually reminds me of what LesD said to me once... he said after a while (of observing) everything is brighter . Blinking true. In 12 mths you'll come back and tell us M8 is so bright thru binos that you now have to wear sunglasses.

In my last session I viewed M13 for the first time in my 10", agreed the transparency of the sky was was bad and dew was starting to affect my image, and all I could was a very dim fuzzy patch of unresolvable stars (note- you may see this sentence repeated in my next obs report ) and I thought, crickey you & Jason saw that thru your binos, you guys are legends. Then I spared a thought for the poor North Americans/Europeans because that's actually their brightest globular cluster.. poor things.
I just looked up Wikki to check my information on that and it says

However, due to its southerly declination, M22 never rises high in the sky and so appears less impressive than other summer sky globulars such as M13 and M5.

Regarding Omega Centauri - Shell, you're not far away from me- you can see it easily, it looks like a dim large star.

Have a go at the technique I use...
Starting from Hadar, I join up to the next bright star which is Epsillon.
I use Zeta & Epsillon to form a triangle using Omega Centauri; it forms an easily discernible triangle.
Omega Cent. is 4 deg. (that's nearly the width of three fingers out stretched closing one eye) from the mid point of Z & E Cent. to make the triangle with Omega.
Stare at the space for a tiny bit and it will pop out.

Even from my front yard between two street lamps I make it out so I know you will too. Tuc too is also visible naked eye on a nice night. I use Omega Cent. to judge the conditions of the sky before observing. If it's really faint, I know not to expect too see too much detail in anything.. as with what happened in my last session (re M-13 mentioned earlier).
P.S. Les will be proud of the correct genitive usage here.
Regarding what Les said...

You are certainly right about IC 2602 -- it is one of the very best open clusters for binoculars. It is interesting that you noted Spica's colour but didn't see colour in any of the stars in IC 2602 -- which are about as blue as they can be to our vision. There are three stars in the cluster with B-V values that are "more blue" than -0.13 -- the same as Spica. Theta itself is -0.20 (which is exceptionally blue).

I am soooo going back there to find those three blue stars. I'm trying to decipher blue & white stars thru my scope at the moment, so thanks Les for the info. It helps when trying to learn types of star spectra, that someone points you to the really bright and blue ones to start the learning curve. For me, even the blue star in the Jewel box can sometimes be a challenge making out the blue depending on the conditions of the sky- some nights it's very apparent and some nights I've got to try really hard making it out from the white one next to it. Must be really easy to spot for people that have been deciphering them for a while. I seem to make out the yellow shades really well tho (I guess there easier). Aye, I have a long way to go, but it's so much fun. As you and I are learning spectra types together, we can help each other Shell!

Can't wait to see more reports from you through your binos.

[goober (Doug)]

Nice stuff - I love Musca - it's my naked eye sky test

[ngcles]

Hi Suzy & All,

Originally Posted by Suzy

Have a go at the technique I use...
Starting from Hadar, I join up to the next bright star which is Epsillon.
I use Zeta & Epsillon to form a triangle using Omega Centauri; it forms an easily discernible triangle.
Omega Cent. is 4 deg. (that's nearly the width of three fingers out stretched closing one eye) from the mid point of Z & E Cent. to make the triangle with Omega.
Stare at the space for a tiny bit and it will pop out.

Okay, I find it just as easy to draw a line from Beta Centauri through Epsilon Centauri and extend it once in the same direction. Beta and Epsilon "point" at Omega, as does a line from Delta through Gamma Crucis (and no one, not one of you will flippantly ask ... "oh do you mean Garcrux?" -- be warned ... grrrrr

Originally Posted by Suzy

P.S. Les will be proud of the correct genitive usage here.

... he is indeed!

Originally Posted by Suzy

Regarding what Les said...
I am soooo going back there to find those three blue stars. I'm trying to decipher blue & white stars thru my scope at the moment, so thanks Les for the info.

You should also bear in mind that we all see colours a little differently, so what I say on colour may not be in complete agreement with your view -- there's no right or wrong here, it just the way we see it. (ie your mileage may vary).

It interests me (I like experimenting on people) when I'm at work at the obs and I show people Spica in the night sky and ask them what colour it is? About half the people will say "white" instantly, about 1/3 will say "light blue" and of the rest, there are a few that say "mid-blue" and significant residual will answer "greenish". We all see colour at least a little differently -- it is a combination of the eye's age, the brightness of the star (more light means better sampling by our eye's cone cells) and our genes I think. Kids always dominate the group that tend toward blue, probably (I'd guess) because their cornea is more transparent to shorter wavelengths that those of us with a decade or few under our belts. To me, Spica appears "sky-blue" naked-eye.

But, when I show Beta Centauri, almost everyone seems to agree it is blue -- because it is sitting next to yellowish Alpha Centauri of course (there will be one or two who will still answer "white"). Contrast always helps (but in some cases can be deceptive). Same thing with Gamma Crucis, next to Alpha and Beta Crucis it appears decidedly more warm-toned than when looked at in isolation. Take a look at a few of the colour-contrasting pairs like h 3945 in Canis Major or Dunlop 94 in Carina etc etc. Describe the colour of the "bluer" star and then look up its spectral type. While the "blue" star in Albireo is genuinely blue (B0) The other two blue components aren't really that blue at all. In the case of Dunlop 94 it is a B9 star (that should appear white or perhaps cold white) and in h 3945 the "blue" star is an F0 star that has the same colour temprature as Canopus, but looks a strong sky blue in moderate apertures -- because of contrast.

Stars with a B-V figure around the -1.3 mark and higher (ie higher negative number) are about as blue as the human eye will normally perceive. There are stars with higher B-V figures (up to around -2.5 in fact) but that usually translates into more ultra-violet light that your eyes can't see at all. "O" type stars aren't more "blue" to the eye -- they're just putting their energy out at wavelengths we don't see well or at all. Naos (Zeta Puppis) is an excellent example of this. Of the bright naked eye stars, Zeta Puppis has the highest spectral type (O5) but looks perfectly white to me -- because its peak output is well into the ultra-violet we can't see. If we could see U.V and our atmosphere didn't scatter it so strongly, Naos would be a brilliant beacon as bright as Jupiter.

The spectral types B1-B3 are normally as blue as you can see in a star. Optical aid (because it gathers more light which in turn switches on your cone cells more readily) accentuates the colour.

Hope this helps.


Best,

Les D