Baade’s Window and other Globulars

[Qualia]

From a true, dark sky, nothing can compare to a naked eye view of the summer Milky Way. It is said to be so bright that if you could clean away the dark rift of stardust that splits the bright streamer in two, it would cast shadows.

Where I live, I can hardly imagine a decent sight of the Milky Way, let alone one casting shadows. From home it is a soft glowing smoke emerging from Sagittarius and drifting upwards to the two gigantic birds of the summer - Cygnus the swan and Aguila the eagle. It is a tenuous river of light, a gathering of cloud as delicate as the mist that often clings to mountains and hills nearby.

On our cosmic journey around the Sun, during the summer we are able to train our scopes onto the constellation of Sagittarius and aim for the direction of our Galaxy’s nucleus. Unfortunately, the concentration of dust and gas is so dense that visible light from this direction is effectively blocked from view and the delicate stream of the Milky Way is broken into islands of darkness. Just as light pollution and clouds are frustrating for the astronomer, so too cosmic dust. Its thick cobweb of glittering darkness also limits how much you can see and how far you can peer into the Galactic Core some 26,000 light years away.

In the years of World War II, Walter Baade took advantage of the imposed blackout conditions and trained the Mount Wilson 100” Hooker reflector onto a tiny 1º clearing he had found while searching for the centre of the Milky Way galaxy. Realising its significance, he started examining the variable stars therein whose pulsating periods of luminosity make them excellent distance indicators.

Over a number of years, using these measurements and those taken from a few other smaller clearings in the night sky, Baade recalculated the known size of the universe and the distance to our Galaxy’s core, effectively doubling all previous calculations.

With my small 10” in hand, I decided to set out on Baade’s quest last night and see for myself what could be found lurking beyond this tiny window. The summer sky is full of extraordinary objects that float on the summer river of light. Albireo -  two stupendous suns of sapphire and topaz. Cygni 61 the first star to ever have its distance measured. Crested Swan Nebula like M 17 or the Veil Nebula like delicate lace, the fingerprint smudge of the Dumbbell easily visible in small binoculars, huge globulars like M 20 split into ribbons of light and dark while open clusters like NGC 6530 appear to nestle and burn themselves in a folded blanket of nebulosity.

An easy star-hop from Gamma Sagittarii, a giant star some 97 light years away and bloated to 12 times the Sun’s radius, you will know you have found Baade’s window when you spot NGC 6522, a tiny, unresolved, mushroom shaped globular some 20,000 light years away. Estimated to be around 12,000 million years old, it is one of the oldest, if not the oldest object in our Galaxy.

If your eyepiece has a reasonable field of view, while observing NGC 6522 you should be able to spot NGC 6528 just 20’ away. Somewhat fainter than NGC 6522, it is, again, an unresolved globular residing even closer to the Milky Way’s bulge at some 25,800 light years away.

As you wind your way slowly from these two globulars, you should be able to note the dark nebulae creeping in on all sides and this is revealing. In themselves, these globulars may not be as spectacular as something like an M 13 or M 20. Sure, they don’t explode like chandeliers or hang in the darkness like cosmic spider plants but for what they lack in beauty, they make up for in devotion: faithful torch bearers almost as old as the Galaxy itself, illuminating and guiding our way for eternity towards the Galaxy’s deep and violent core.  

By way of passing, while you’re in the area of Baade’s Window, it is also worth a little time checking out some of the following globulars:

NGC 6540 – quite a faint and small globular. With high power – 200 x and more – some stars can be resolved but nothing too clear.

NGC 6544 - bright and reasonably large globular with some stars resolved at around 120x power. Framed by a pretty asterism.

NGC 6553 – bright and relatively large globular; worth throwing power at, for some stars can be resolved.

NGC 6558 – bright but pretty small globular whose core can be resolved just a little at about at about 200X.

NGC 6569 – quite a bright, large globular which can be resolved at around 160x into a dozen or so stars with a very grainy backround.

NGC 6624 – globular cluster whose small core appears quite condensed, surrounded by a relatively large halo giving hints of resolution.

NGC 6652 – globular near M 69 and M 70, it has a small core and a small halo around it.

M54, M 69, M 70 – three Messier globulars at the base of the Sagittarius teapot. M 54 is the brightest.

[John]

What a super report Rob - you really do write excellently and fluently about our hobby

[xtreemchaos]

great report mate and a fantastic image,theres nothing like the milkyway for stiring the soul.thanks for sharing..charl

[cotterless45]

Superb report a Rob, thanks for posting. I love following in footsteps,

Nick.

[Qualia]

Thank you for your kind comments. It was a nice night looking beyond the window

[Piero]

You transformed a report in a little piece of literature. 

It is a real pleasure to read it!

Thanks, 

Piero

[Owmuchonomy]

Thanks Rob! I have craved to look at the core for years but at 54' N, no chance.  Now I am craving it more than the piece of Paradise Slice I glimpsed in Boroughbridge High St over lunch.  I must get my (our) act together and get my tin snail down to lower latitudes.  I guess today I have empathy with Hubble who must have thought the world had ended when Baade move his estimates out.  He had such pride over the accuracy of his measurements.  Thanks for the nice report.

[swamp thing]

Cheers Rob for a most enjoyable read. I might well have a wander around there next time out.

ps You may wanna change that M20 reference to M22. M20 is the triffid nebula, M22 is the giant Glob

[JamesF]

Lovely report.  Shame there's no room in the car for the 10" dob when we go to France this summer

James

[michael.h.f.wilkinson]

Great report Rob, really superb

[niallk]

Wonderful post!