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Old 25-05-2015, 07:21 AM
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Weltevreden SA (Dana)
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Djorgovki 2, Ton 2, and Haute Provinvce 1

In my 33° S latitude skies, Sco-Sagg are directly overhead around midnight to 1:00. I live in the Arizona-like Karoo of S Africa with Namibia-qual seeing, so I regularly use Djorg 2 Sagg, Ton 2 in Sco, & HP1 (ESO-455-11) Oph as seeing-quality test objects. Djorg 2 near the B86 Ink Spot is steady in averted using a 6-inch MakNewt, almost exactly in the middle of a keystone much resembling the torso of Hercules. It stands out in averted in a 7” and is visible direct in an 8”. At integrated 9.9 it's the brightest of the Djorgs and has the core appearance of a Class VI or VII. Ton 2 at 12.2 is unobtanium in a 6, shows hesitantly in my 7" f/10 and a 7" f/15 Maks on the best nights, and is steady in averted 50% of the time in an 8" f/12 Mak. Being reddened 1.25 mag really shows given its visual diameter -vs- luminosity disparity. Haute Province, HP 1, is visible in both 7" and 8" as a furry star which lies as the tip of a Corvus or Draco-head asterism of 11 - 12 mag stars. It looks like a ~12 mag star on a bad hair day, and even then only at 200x and above. It is a highly core-concentrated cluster with 7 mag ~14 stars in a 1.5 arcsec dia ball, falling away to a large but tenuous halo which might not show even in a large dob. All these are fossil bulge GCs with low metallicities and orbital paths exhibiting unusual tidal stripping properties. As these clusters orbit around the bulge, they gain approx as many stars on the fore side of their path from bow wake compression, as are lost from the aft side from tidal stripping. Halo stars easing outward in globulars do not just wander off willy-nilly in any direction, but can escape only through their Lagrange L1 and L4 points—and then only if their orbital path is aimed within a 7° cone in the net-zero tidal zone directly away from the cluster. HP 1 loses the most because it is a core-collapsed cluster (hence the tight, bright core). Even then it loses only 1 or 2 stars every million years. Today’s old bulge globulars were formed slightly before or about the same time as the bulge itself. Life inside one of these during their first few billion years would have resembled life in the middle of Omega Cen today, lots of bright things dotting about and not much else.
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Old 25-05-2015, 09:40 PM
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mental4astro (Alexander)
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Hi Dana,

I remember you first mentioning DJ 2 some time ago. I chanced upon it last year for the first time after I completed a sketch of the neighbouring Ink Spot. By chance as a mate mentioned it being very close to the Ink Spot after he found it on Sky Safari. I kicked myself afterwards as the trio actually did fit in the FOV of the eyepiece I was using. The trio makes a stunning combination.

As you say, DJ2 is a very subtle object. It is heavy obscured by the Milky Way, so it is very easy to miss. By chance DJ 2 sits in a slightly dimmer section of mottling so it is possible to make out its circular structure. It certainly does not stand out by any amount. It is very subtle and delicate, and requires patience to identify.

What I found so lovely about the trio of the Ink Spot, the brilliant open cluster beside it, and DJ 2 is they all present such different spectacles in their own right as brilliant, dark and difficult, all against the magnificent mottling of the Milky Way, and all in the one FOV. I am eager to revisit this part of the sky. For me a really beautiful and special part of the sky.
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Old 26-05-2015, 08:29 AM
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Weltevreden SA (Dana)
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We must be its only fan club

Hi to you, too, Alex . . .

If Djorg 2 is not exactly big news in the enthusiast forums like IIS, it’s all but terra incognita in the professional literature. Since Djorgovski’s 1987 discovery paper there has not been one dedicated study of it. There’s no CMD of it and no one has logged its orbital parameters. It’s mentioned by its official name ESO 456-SC 038 in 16 general papers about this or that occurrence frequency, e.g. binaries or X-ray emission, but aside from a table entry or footnote the poor thing is awful lonesome out there. We must be its only fan club. And if the NED image are to be trusted, we also seem to be seeing it as a lot grander than the catalog images have it. A UK Schmidt image of it has been its official class portrait since 1994. It looks a but wan in that image, just as the WikiSky image of it looks way too saturated. Its 3.2 mags of extinction hasn’t helped its case much. Except for a few fans like us, it might as well be not there. We should send it a Get Well card or something.

Sure is in a pretty field, though.

=Dana
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Old 01-06-2015, 10:10 PM
Rob_K
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Good work Dana! I've seen Djorg 2 through a 4.5" in very dark skies - my notes just say "Obscured in starfield – very faint, very small glow in 4.5-inch scope". Ton 2 (Pismis 26) & HP 1 are a bridge too far I think! I have gone for Ton 2 previously without any luck but can't particularly remember ever trying for HP 1.

Cheers -
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Old 02-06-2015, 05:40 PM
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Rolf Olsen has it in one of his fabulous pix, not as the subject but included.

http://www.rolfolsenastrophotography...ulae/i-S46pSRS
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Old 03-06-2015, 10:18 AM
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mental4astro (Alexander)
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That photo of Rolf's shows just how tricky it is to identify Dj 2. It also shows that it lies in a slightly dimmer part of the Milky Way, and the obstruction give it a slightly ruby colouration in the photo. Thanks for the link, Brent,
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