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Old 04-06-2011, 10:20 PM
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Observation Report 4/6/11

Well, Sat night promised to be quite nice, and after some ugly cloudage during the day, the evening cleared up nicely. With that, I lugged out the scope and all my stuff, and began observing at 7pm. Seeing was crap as usual. Saturn broke down at 200x, continuing the theme of this year. However, transparency was up there so was looking like a good night for a few galaxies. Because of the crud seeing, focus was not very crisp at all at 267x, even the 167x view was noticably worse than what I'm accustomed to after the last couple of years. Nevertheless, this was of little consequence for galaxy hunting. The session was destroyed after mere 1.5 hours by Melbourne Cloud, and after 45 minutes of waiting it looked to be only getting thicker so I threw in the towel.


Scope: 12" F/4.4 truss dob
Time: 7pm-8:40pm
Seeing: 2/10
Transparency: 4/5
Dew: None
Temp: 9C


UGC 8322
GX, Virgo, RA 13 15 01, Dec +12 43 28 , Size= 1.3x0.3' , Mag B= 14.8

A Faint, barely suspected smudge at 167x, but switching to the 5mm EP at 267x improved the view dramatically. The galaxy was now relatively easily identified, showing slight elongation approx N-S, forming a triangle with a pair of mag 13 stars to the north and SE. The sighting was confirmed using wikisky. This galaxy lies approx 350 million light years distant.

-----------------

NGC 4727
GX, Corvus, RA 12 50 57, Dec -14 19 59 , Size= 1.4x1.1' , Mag V= 11.9
Brightest of several galaxies in the area. Other objects observed include IC3831, IC3827 and MCG-02-33-017. NGC 4727 and its companion NGC 4724 appear to be twice as distant, despite being somewhat brighter than the three aformentioned galaxies, with a distance of approx 345 million light years compared to about 180 million for the IC and MCG objects. Fairly bright and diffuse at 167x, hints of elongation but not clear. 267x confirms elongation as SE-NW. NGC 4724 lies less than 1' to the west.


NGC 4724
GX, Corvus, RA 12 50 53, Dec -14 19 56 , Size= 1.1x0.8' , Mag V= 12.7

Stellar core, hint of surrounding haze at 167x, increasing mag to 267x provided a slightly better view with the haze more obvious and hints of E-W elongation. A fairly bright but tiny object. Located less than 1' W of NGC 4724.

IC 3831
GX, Corvus, RA 12 51 18, Dec -14 34 26, Size= 1.4x0.8' , Mag B= 13.8

Located about 15' SE of NGC 4724. Spotted at 167x, but at 267x it appeared as a compact high surface brightness galaxy, slightly condensed towards the core with hints of N-S elongation. This galaxy, along with IC 3827 and MCG-2-33-017 is not gravitationally bound to NGC 4727/4, as the latter lie roughly twice as far despite appearing to share common ground from our vantage.

IC 3827
GX Corvus, RA 12 50 52, Dec -14 29 34, Size= 0.9x0.7, Mag B= 14.05

Located 10' due south of NGC 4727. Very faint, barely seen at 267x, as a non-descript low surface brightness dust mote.

MCG-2-33-017
GX, Corvus, RA 12 50 05, Dec -14 44 00, Size= 2.3x2.2', Mag B=12.9

This is a surprising object, forming an extremely close "pair" with a mag 12 star just 25 arc seconds to the south! Easily spotted at 167x as a patch of low surface brightness haze, but increasing mag to 267x showed a tight diffuse core surrounded by a low surface brightness circular halo. DSS images show a face on spiral that resembles the ripples in a pond when one throws a stone in it rather than a "traditional" spiral with arms.

------------------

ESO 269-57

GX, Centaurus, RA 13 10 04, Dec -46 26 14, Size= 3.4x2.4' , Mag B= 12.5

Been wanting to observe this ring galaxy since reading about it in one of Paddy's obs reports. He reported sighting the ring, but from my location I could not see it. Still, at 267x the core was bright and roughly circular, with a pair of 12.5 mag stars located 1.5' SE (which mark the ring location according to DSS images) and a fainter Mag ~13 star is located just 45 arc seconds W of the core. The galaxy is set in a lovely field.


------------------

Btw, here is proof of the crap seeing: this jet would've been flying against 200km/h winds atleast
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Old 11-06-2011, 11:26 AM
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Good to get some obs in and galaxies in particular. Interesting about the distance between NGCs 4727 and 4724. Hope you get to see the ring around ESO 269-57 - I imagine dark skies would be essential
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Old 11-06-2011, 06:13 PM
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Thanks Paddy. Was a successful galaxy session, everything seemed to go right, my targets were well seen and yeah it was cruisey. For ESO 269-57, dark skies are mandatory, and having just bought a car, I can now go and fish out a few dark places but can't because my folks reckon I'm going to get attacked and die.

That reminds me, I've still got one obs report from late April that I need to type up.
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Old 11-06-2011, 07:37 PM
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mental4astro (Alexander)
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my folks reckon I'm going to get attacked and die.
Yowies are surprisingly quick, . Just make sure you go with a mate that's slower on their feet than you.

Neat report Sab. I particularly like how you've concentrated on the lowly Corvus. It is so surprisingly rich in galaxies for its modest size.
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Old 11-06-2011, 08:58 PM
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Thanks Alex. I think my folks watch too much brainwashing garbage like Today Tonight!

I don't generally focus on any constellation in my observing, I just select objects anywhere that appeal to me by RA, so I have a nice list to follow methodically as the Earth's rotation carries them across the sky.

cheers

Last edited by pgc hunter; 11-06-2011 at 09:13 PM.
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Old 12-06-2011, 03:07 PM
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I can now go and fish out a few dark places but can't because my folks reckon I'm going to get attacked and die.
Better book in for BSG and Snake Valley then. Dark skies and safety in numbers.
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Old 12-06-2011, 06:33 PM
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Better book in for BSG and Snake Valley then. Dark skies and safety in numbers.
I could but I prefer observing alone or only in a small group.
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Old 14-06-2011, 10:44 AM
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I could but I prefer observing alone or only in a small group.
I figured that - I do just hold out a little hope that we'll meet you one day at Snake Valley.
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Old 16-06-2011, 12:30 AM
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I figured that - I do just hold out a little hope that we'll meet you one day at Snake Valley.
Hey Paddy.... main reason I don't attend Snake Valley is due to uni and work commitments, just no time! Also had no car until now, but still my schedule is quite full on so finding time to attend the camp is near impossible

But we can always organise a small get together somewhere sometime
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Old 16-06-2011, 04:07 PM
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But we can always organise a small get together somewhere sometime
Sounds a very good idea. Trick would be to find a good place to meet.
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Old 16-06-2011, 09:50 PM
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Sounds a very good idea. Trick would be to find a good place to meet.
I've got a potential site near heathcote.... I'll try and get out there one of these days and check it out.
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Old 17-06-2011, 10:29 AM
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Heathcote sounds quite a manageable option.
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Old 17-06-2011, 01:12 PM
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Heathcote sounds quite a manageable option.
On Google Earth it appears to be a grassed area at the end of a dirt road, looks like there is enough space to set up. It's surrounded by farmland. It's quite removed from any major settlements or paved roads.

I might be able to get out there tomorrow or early next week and assess the site.
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Old 17-06-2011, 02:51 PM
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I have wondered about possible sites near me (In the hills near Kilmore) that might give nice broad horizons but hopefullyblock a fair bit of the skyglow from Melbourne. Preferably acessable with a sedan or a softroader at worst.

Home is not too bad but I am on a curve in a major road so headlights regularly sweep the place from side to side.
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Old 05-07-2011, 10:00 AM
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NGC 4727 & NGC 4724 - a mysterious pair

N4727/4724.....that's an interesting close pair of galaxies, Mr PGC Hunter! (do you like PGC galaxies?!?)

It is very poorly studied by professional astronomers, judging from the very few papers mentioning it in the last 30 years.
(see: //adsabs.harvard.edu , the astronomy and astrophysics abstracts service)
When I looked in the public Hubble Space Telescope archive at //hla.stsci.edu, again, there was no imagery available....so, this is a mysterious pair!! Furthermore, it is outside of the SDSS footprint, and there is little about this galaxy pair in the data archives.

Here is the DSS image (a composite of ER + J images), which I downloaded from the (usually) excellent online version of DSS known as Aladin(//aladin.u-strasbg.fr). Normally, these images are quite good (about equivalent to a modestly good amateur CCD image), yet this particular scan of the Schmidt plates is particularly poor.

Click image for larger version

Name:	N4727_ER + J__SERC DSS2 + SERC DSS1__download from Aladin.jpg
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An image search at the comprehensive NED extragalactic database (//nedwww.ipac.caltech.edu) also comes up nearly empty handed;
but - lucky for us - the available Near infrared image (J+H+K composite) from the 2MASS survey is good enough to give us a reasonable idea of what kind of galaxies these are:

Click image for larger version

Name:	N4727_JHK_2MASS.jpg
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We are lucky here, because the best of the 2MASS infrared images are of decent angular resolution. The larger of the two galaxies is obviously a spiral. The smaller of the two galaxies is probably an S0 galaxy (strongly dominant bulge with a small disk/planar component) though the existence of spiral arms cannot be ruled out due to the modest morphological resolution that is available.
The case for these assigned galaxy types is strengthened by the GALEX satellite far-ultraviolet and near-ultraviolet images of this pair, as the spiral produces significant extended FUV emission (presumably from hot young stars in its arms and/or in its inner ring), yet the smaller of the two galaxies has little or no FUV flux which indicates that it is a quiescent disk+bulge system having little or no star formation....in other words, the lack of star formation in the smaller galaxy is strongly consistent with the idea of it being an S0 galaxy.

The prominent central bulge (or the pseudo-bulge, if it is not a spheroidal structure) that is seen in the infrared image of the spiral need not be so prominent at visual wavelengths, as the near-infrared regime can reduce the obscuring effect of the dust within a galaxy by 10 or more times. Another interesting aspect of the spiral is that it appears to have a strong pseudo-ring structure made of two tightly-wound inner arms (in the terminology of the CSRG), with a probable bar structure existing inside the ring.
An existing expert Hubble classification (on the DDO system) for the the spiral NGC 4727 by Sidney van den Bergh, is
S(B)b II with an uncertainty flag, indicating that this is likely to be a barred spiral, perhaps weakly barred, but with a significant degree of uncertainty attached to the assigned Hubble type. I think that NGC 4727 is undoubtedly a barred spiral, from consideration of the several low resolution images that can be found on the internet, and that it does have an inner ring structure that surrounds its bar.
The LEDA database also claims that this galaxy does have a bar structure and a ring structure.

The asymmetry visible in the DSS image of the spiral, with one prominent spiral arm in its outer regions that does not have a corresponding prominent arm on the other side, could be a sign of a mild galaxy interaction or of a past interaction between the two galaxies. However, there is a large difference in recession velocity between the two galaxies, which would indicate a greater probability that this is a non-interacting galaxy alignment in the same-line-sight........ that is, IF my available optical redshifts are correct!! (it is surprising how often redshifts that are made from optical spectra turn out to be incorrect.....HI line data (21cm line) are far more reliable)

A possibility that something more interesting is going on than the line-of-sight alignment of two galaxies that are actually far apart, is indicated by the DSS image found at //wikisky.org
[ The wikisky server does not display the sharpest available Digitized Sky Survey images, but it does display DSS images at high contrast; which is useful for looking for faint outer features in galaxies ]

Click image for larger version

Name:	N4727_DSS from wikisky.jpg
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There does appear to be some unusual and anomalous outer material (or objects) outside of the optical body of NGC 4727, but this would have to be crosschecked with other deeper and sharper imagery.
Of course, if there has been some kind of interaction between NGC 4727 and another galaxy, the perturbing object need not be the most obvious smaller companion that is very easy to see (NGC 4724). Indeed, there seem to be one or two very small galaxies near to NGC4727 that are candidate perturbers.

cheers,
the mad galaxy man

Last edited by madbadgalaxyman; 05-07-2011 at 12:01 PM. Reason: more info to be added
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