This month’s Challenge is a real mixed bag. From naked eye fare, through to eyeball cramping, AND a special treat for the early risers – a “Death of the Dinosaurs” galaxy. Also, to pep up a bit more participation, a bit of a “Sketch-a-Fest”.
Naked eye
July sees the transition from the ‘galactic objects’ to the ‘extra-galactic’. The evening sees the ‘heart’ of the Milky Way arch over our heads. Even from light polluted skies, the distinct concentration of brighter stars that inhabit the main band of the Milky Way is noticeable. Skies that are a little less light polluted will reveal soft concentrations of open clusters and nebulae. Dark skies will show the full extent of the milky Ways brilliance, as the innumerable faint background stars collectively mark the galactic disk, & dark menacing fingers of dust & gas cut through this brilliance.
The Cloud of Sagittarius, the densest example of the former, happens to shield the galactic centre from our eyes (30,000 light years away). The Coal Sack, and example of the later, lies smack bang between the Southern Cross & the Pointers.
Early evening sees the Milky Way stretch from the western horizon, across to the eastern horizon.
Scope targets – Easier
M87, galaxy in Virgo. M87 lies towards the lower northern part of our sky. This supergiant galaxy is King Dog of the Virgo Super cluster of galaxies (of which M104, the Sombrero, is one). Smaller scopes will show it as a faint, unresolved blob, somewhat globular-cluster-like. The largest of scopes will begin to reveal some of its 4000 globular clusters that orbit around it.
M 17, the Swan Nebula, nebula & cluster in Sagittarius. The poorer cousin of the M8 complex, also in Sagittarius. M17 is also a naked eye object, even in moderately light polluted skies. The distinct curved “Z” shape, that resembles a swan in profile, is seen even in modest sized scopes. Larger scopes will show more detailed structure within it.
NGC 7293, the Helix Nebula, planetary nebula in Aquarius. The largest & presumably closest planetary nebula. Binoculars or a rich-field-telescope, are the best way to see this faint “doughnut”. An OIII filter will help show it up and some of its curious corkscrew structure may be discernable.
NGC 1398, galaxy in Fornax. The “Death of the Dinosaurs” galaxy I mentioned earlier. I say this as this galaxy lies 65 million light years from us. On looking at this galaxy, we are looking back into time towards the end of the reign of the dinosaurs. This galaxy is face on to us, & larger scopes will begin to show its barred spiral shape.
Eyeball Cramping offerings
NGC 6027 et al, Stephan’s Sextet, galaxy cluster in Serpens Caput. Larger amateur scopes (12” +) will be able to glimpse the five brighter members of this sextet. The sixth being only a photographic object.
Abell 2065, galaxy cluster in Corona Borealis. This one should see your eyeballs throb! This cluster of some 400 galaxies JUST shows its brightest 12 members in scopes 16” and over.
1’st “Sketch-a-Fest”
To try to pep up a bit the participation in the Challenge, I thought of a push for a bit of a sketching fest of one target. Astronomy aficionados come in all ages, & using all manner of gear. So how about a collection of works of the beautiful, colourful open cluster The Jewel Box in the Southern Cross.
Doesn’t need to be done this July, can even be as old as Captain Cook. Just a collection of studies that show the beautiful range of handiwork.
The Jewel Box is an easy early evening target, especially good for those with an early bedtime. Digital sketch, pencil and paper, it doesn’t matter.
Just have a go at it and upload a pic of it. Maybe also add the scope used, and the magnification too. Easy.
To add to the 'mixed bag', what about a comet? Comet C/2009 P1 (Garradd) is brightening nicely in late evening/morning skies. Currently situated in Aquarius, near the Aquarius/Pisces/Pegasus junction. Around mag 9 at the moment.
Sab, please, only ment with "poorer" as if it were in any other constellation, it would get mentioned more! Sheesh, .
Love the Jewel Box sketch. Ta.
M8 just seems disappointing compared to M17. The former has far lower surface brightness than the latter and can only be seen to good effect from darker locations. M17 however exposes a great amount of detail in any moderate sized scope that M8 lacks.
M17 is one of the most underrated DSOs out there.
Last edited by pgc hunter; 30-06-2011 at 09:23 AM.
Apologies in advance for the pedantry, but Stephan does not have a Sextet, instead he has a Quintet -- it is in Pegasus not far from the bright eg NGC 7331.
The Sextet is Seyfert's -- Seyfert's Sextet in Serpens (nice bit of alliteration there).
I can confirm it is visible as a common merged halo, June 2000 31cm at x186:
Pretty challenging. All 6 share a common halo which is in shape a mirror reversed inverted "L". C is the most obviously detached, as a tiny elongated patch of haze which seems to grow to the axis, 20' x 10". 2 others appear as enhancements or condensations within the merged halo, -27A which is just N of "c" as the middle of the shank of the "L". E is also a separate extension within the halo.
So go for it.
NGC 6027D (of Hickson 79E) is not an actual component of the cluster but far in the background (contrary to the wiki article). Its R/V (+19,800 Km/sec -- odd) indicates a distance out around the 900 million ly mark and it is one of the most distant normal eg visible in moderate-sized amateur instruments. It is seen resolved as separate from the "L" shaped merged halo in 46cm at x317.
As for AGC 2065, at least 1 member of this remote cluster at about the 1.1 billion ly mark is an extreme threshold object (and I mean it!!) in 31cm at moderate/high magnification under a high quality rural sky:
PGC 54876: x186 26' TF. Mag 15.1 Size 0.4' This is a very, very difficult observation. Found - there is a line of *s in roughly PA 45 from the N mag 12, 13, 13.5 *s from NE-SW. Middle * is displaced to the SW from centre. From that * in PA 60, 2.5' distant is a threshold dot only 10" diameter which is very occasionally visible about 4x in 5 mins of observation. Only very occasionally wafts into view for a couple of seconds, 80% certain. G Mitchell confirms.
This eg PGC 54876 is 1.3 arcmins in PA 72 from GSC 2031:972 at mag 11.1. Strangely, I haven't been back to revisit this cluster with 46cm. Maybe I'll do so at the end of the month. That magnitude for PGC 54876 is a true V magnitude and no dinky (B) or (P) (IR), (Z) some other form of rubbery guesstimate. Any extended object (even though only 10" diameter) at V mag 15.1 for 31cm is an extremely tough target unless you have super-eyes (which I don't).
Oh and BTW ... How many pedants are needed to change a light-bulb?
Haven't had much chance to get out this month but here is an interim report as I hope to get to the dark site next Saturday weather permiting.
It was still partly cloudy when I went out last night so I was only planning on doing my Jewel Box sketch. But once this was done the sky was clearer.
I had no particular plan and didn't take notes either. I did seek out M17 which was high overhead at the time. I could see the body of the swan clearly with a distinct dark line running down one side. Seeing this dark line gave a hint of the fainter surrounding nebula. From my backyard I could not clearly make out the neck or head of the swan. I hope to get back to this one on Saturday.
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