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Old 08-03-2016, 07:09 PM
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ngcles
The Observologist

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Location: Billimari, NSW Central West
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Observations of AGC 3574, 8 March 2016

Hi All,

Had a fun session under the stars last night that I spent testing some new equipment, doing a bit of favourite spotting and lastly, in taking up the Pepsi challenge from a friend who is not part of this forum to observe Abell Galaxy Cluster 3574 in Centaurus.

One of the (many) nice things about living in a virtually pristine deep-sky site is that you have no real time-pressure to finish up an object (s) and move on, there's always another night. I spent the best part of an hour sleuthing-out this cluster that lies around the 200 million light-year mark and is fairly close-by to the bright, detailed Messier 83. There was one galaxy I had some trouble identifying, while it is plainly visible on the DSS, it was apparently passed-over by those who compiled the better-known galaxy catalogues and was identified by way of inquiry on SIMBAD (have I ever mentioned how much I hate the SIMBAD interface) rather prosaically as 6dFGS gJ134806.5-303205 -- presumably from the 6dF survey at compiled at Siding Spring using the UK Schmidt.

Anyway, here are the notes from about 1.30am 08032016. The SQM-L reading at the commencement of these observations was 21.91 mags/Sq arcsec, I rated the seeing at 6/10. The eyepieces used were 12mm TII Nagler and 9mm Nagler, x185 27' TF and x247 20' TF respectively.

AGC 3574 Galaxy Cluster
RA: 13h 49m 12.0s Dec: -30 17' 00"
Mag10: 13.0 (V) Mag3: 11.8 (V) Mag1: 11.4 (V) Size: 56.0'
Class: 0 1 I # Galaxies: 31 Source: RCG


IC 4329 Galaxy *
RA: 13h 49m 05.3s Dec: -30 17' 45"
Mag: 12.2 (B) S.B.: 13.9 B-V: +0.90 Size: 3.5'x2.2'
Class: SAB(s)0- P.A.: 63 Inclination: --- R.V.: +4527 Source: RC3 *

This is the central and brightest member of AGC 3574. Is a mod bright eg easy to see probably 1.25-1.5' diameter slightly elong in PA 90(?) growing slightly and broadly to centre and at centre is a not well defined, small, weakly brighter core containing a faint stellaring. Diffuse edged halo. -29A is 3' E.

IC 4329A (ESO 445-50) (PGC 49051) Multi-Galaxy Sys *
RA: 13h 49m 19.3s Dec: -30 18' 33"
Mag: 13.0 (V) S.B.: 12.0 B-V: +0.97 Size: 2.6'x0.7'
Class: SA0+: sp P.A.: 50 Inclination: --- R.V.: +4793 Source: RC3 *

A small mod faint spindle with slightly lower SB that -29 in about PA 60, probably 1' x 15" growing to the axis near centre and appear to have an occasional stellaring nr centre.

NGC 5298 Galaxy *
RA: 13h 48m 36.4s Dec: -30 25' 43"
Mag: 13.0 (V) S.B.: 13.1 B-V: +0.88 Size: 1.9'x0.8' Class: SB(r)b
P.A.: 73 Inclination: --- R.V.: +4412 Source: RC3 *

Is about 11' SSW of IC 4329 and part of a group including NGC 5302 that forms a rough square 6' a side. -98. Mod faint eg lying in a small triangle of 13th and 2 14th mag *s, seems elong in about PA 60 1' x 30", growing broadly and slightly to centre without apparent zones or nucleus. -302 is 6' SSE.

NGC 5302 Galaxy *
RA: 13h 48m 49.5s Dec: -30 30' 42"
Mag: 12.0 (V) S.B.: 13.1 B-V: +1.00 Size: 1.9'x1.1' Class: SB(s)0+:
P.A.: 159 Inclination: --- R.V.: +3549 Source: RC3 *

This eg has an oval outline 1.25 x 50" in about PA 150 rising broadly and weakly at first and then near centre, moderately to a small core zone and an occasionally *ar nucleus at centre. It has a mag 14 * off the W flank by 1'.

ESO 445-35 (PGC 48950) Galaxy *
RA: 13h 48m 11.1s Dec: -30 27' 07"
Mag: 14.0 (P) S.B.: --- B-V: --- Size: 1.3'x1.0' Class: SB(rs)b P.A.: 166
Inclination: --- R.V.: +4899 Source: RC3 *

is 6' W of -298 and found in a small rectangle of mags 14 & 15 *s small, 40" diameter, round, and lower SB than the two nearby NGC egs, mod faint, growing weakly to centre where there is a small slightly brighter zone and a suspected stellaring core/nucleus.

MCG -5-33-9 (PGC 48955) Galaxy *
RA: 13h 48m 14.7s Dec: -30 33' 03"
Mag: 14.9 S.B.: --- B-V: --- Size: 0.9'x0.8' Class: L
P.A.: 173 Inclination: --- R.V.: +5237 Source: PGC *

ESO 445-37 (PGC 48956) Galaxy *
RA: 13h 48m 15.9s Dec: -30 34' 30"
Mag: 15.3 (P) S.B.: --- B-V: --- Size: 0.8'x0.3' Class: S?
P.A.: 62 Inclination: --- R.V.: +4238 Source: RC3 *

6dFGS gJ134806.5-303205
RA 13 48 06.544 Dec -30 32 04.69
Mag 14.94 B

MCG -5-33-9, 6dFGS gJ134806.5-303205 and ESO 445-37 are at the south western and fourth corner of the 6' x 6' square with the above 3 egs. The first two are very similar looking very small spots of gossamer about 20-30" diameter with no structure visible. ESO 445-37 is a tiny sliver of featureless gossamer in PA 60 30 x 5" with a highly distracting 13th magnitude * immediately off the NW flank. Took a little time to pick this one up. Very, very faint

ESO 445-44 (PGC 49018) Galaxy *
RA: 13h 49m 00.6s Dec: -30 37' 30"
Mag: 15.0 S.B.: --- B-V: --- Size: 0.8'x0.8' Class: Sb
P.A.: --- Inclination: --- R.V.: --- Source: PGC *

This eg is about 7' S of -302 and is a very, very faint spot that at first looks like a 15th mag * but at x247 is revealed as a small, 30" diameter spot of gossamer with a mag 14.5 - 15 * embedded in the eastern halo. Really only barely detectable because of VV LSB.

NGC 5291 Multi-Galaxy Sys *
RA: 13h 47m 24.5s Dec: -30 24' 30"
Mag: 15.1 (P) S.B.: --- B-V: --- Size: 1.3'x0.9' Class: E pec:
P.A.: 157 Inclination: --- R.V.: +4340 Source: RC3 *

Is about 20' SW of IC 4329 and a little E of a pair of mags 10 & 11 *s. Mod faint, lowish SB round spot 30-40" diameter growing slightly to centre with no apparent core or nucleus.

NGC 5304 Galaxy *
RA: 13h 50m 01.5s Dec: -30 34' 42"
Mag: 13.6 (P) S.B.: --- B-V: --- Size: 1.4'x0.9' Class: E+ pec:
P.A.: 157 Inclination: --- R.V.: +3730 Source: RC3 *

Is about 20' SE of IC 4329 is a mod faint eg and close to a small almost perfect Eq tri of mag 14 *s a little of 1' a side. Small, 30-40" diameter, growing broadly and mod to centre but does not appear to contain any core or nucleus. Continuing that line from IC 4329 through -5304 and continuing another 20-odd arc mins is ESO 445-57.

ESO 445-57 (PGC 49180) Galaxy *
RA: 13h 51m 09.2s Dec: -30 46' 52"
Mag: 14.0 (P) S.B.: --- B-V: --- Size: 1.1'x0.8' Class: SB?
P.A.: 123 Inclination: --- R.V.: +5641 Source: RC3 *

Small spot about 20" diameter 2' NW of a 10th mag *, very LSB consistent SB spot about 20" diameter with no structure visible.

ESO 445-60 Galaxy *
RA: 13h 51m 45.2s Dec: -30 38' 03"
Mag: 15.6 S.B.: --- B-V: --- Size: 1.1'x0.3' Class: S
P.A.: 83 Inclination: --- R.V.: --- Source: PGC *

Is about 35' SE of IC 4329 and a few arc mins E of a 10th mag * and is a quite difficult and fain eg, 20 x 10" in PA 90 of consistent SB gossamer only intermittently visible with concentration. No structure. About 7' N of this is the pairing of ESO 445-59 and -59A.

ESO 445-59 (PGC 49208) Galaxy *
RA: 13h 51m 39.4s Dec: -30 29' 18"
Mag: 13.4 (B) S.B.: 14.3 B-V: +1.03 Size: 1.0'x0.5' Class: E?
P.A.: 111 Inclination: --- R.V.: +4550 Source: RC3 *

ESO 445-59A (PGC 49211) Multi-Galaxy Sys *
RA: 13h 51m 41.1s Dec: -30 30' 06"
Mag: 14.9 S.B.: --- B-V: --- Size: 1.2'x1.1' Class:
P.A.: --- Inclination: --- R.V.: --- Source: PGC *

These two eg are N-S of each other only about 1' apart and are both about 20-30" diameter, round spots of gossamer with no structure visible. -59 is probably slightly larger and marginally brighter.

ESO 445-56 (PGC 49162) Galaxy *
RA: 13h 50m 53.6s Dec: -30 17' 20"
Mag: 14.6 S.B.: --- B-V: --- Size: 1.2'x0.4' Class: S0
P.A.: 130 Inclination: --- R.V.: --- Source: PGC *

Is about 20' due E of IC 4329 and situated a little E of the mag 12* that makes the RA, in a small RA tri of *s mags 10, 10 & 12. A thin sliver of faint and very LSB, very elong 50" x 10" and no visible structure.

IC 4327 Galaxy *
RA: 13h 48m 43.8s Dec: -30 13' 03"
Mag: 13.9 (V) S.B.: --- B-V: +0.61 Size: 1.2'x0.6' Class: SB(s)c?
P.A.: 56 Inclination: --- R.V.: +5415 Source: RC3 *

Tis eg is found to the NW of IC 4329 by about 7' and nearby to a 10th mag distracting star to its W. Quite faint, small and elong 40" x 10" slash of gossamer with no apparent core or nucleus.

Best & Clear Skies,

Les D
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  #2  
Old 09-03-2016, 03:33 PM
Bombardon (Eugene)
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I enjoyed your report, Les and while my main glass has shrunk - for ease of use- and all this humidity and mossie ear bashing can test the resolve to get out into my back garden, I have noticed that Interstellarum suggests that NGC 4329 is doable with my 10" and there appears to be a decent lead in spray of stars from 4 Cen(Howe 74), I will try to get there soon.
Thanks for sharing such a great night Regards, Eugene
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Old 10-03-2016, 12:44 AM
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Another sweet as report Les! Your obs of NGC 5291 caught my eye, I have observed this pair myself.

My obs from way back in 2008 with a 10" dob.
NGC 5291
Forms part of the "Seashell" galaxy pair. Now, once again, my sighting of IC879 is re-inforced here. This galaxy has a listed mag of 14.2, with an equally feeble SFC brightness of 13.9, which by all means should not have been visible with a 10" from my suburban sky. When, after careful observation, the galaxy manifested itself in my 192x eyepiece, I could barely believe it I increased the mag to 250x, despite the shocking seeing. This cluster of galaxies was riding the zenith so I had the best seats in da house. Stuff me, at 250x I could not only see the galaxy, which is only 0.3 mags off the theoretical limit of a 10", but I did make out a N-S elongation. Turning to the MSA, the symbol is indeed orientated in a N-S angle!

I should revisit this object, and well the entire cluster from my new location.

Quote:
Originally Posted by ngcles
One of the (many) nice things about living in a virtually pristine deep-sky site is that you have no real time-pressure to finish up an object (s) and move on, there's always another night.
You said it! Having suffered Melbourne's craptacular climate for 2 decades with its endless barrage of cloud and other nuisances, I now feel bloody spoilt. There are so many clear nights here I don't have to worry about missing a night, because the next one will be clear anyway, and my dark site is only a 15-20 minutes drive away.

That being said, this new moon period is largely a write off, very hot and humid conditions with cloud. Hottest and cloudiest spell since I moved here !!! I did experience a few light showers with massive drops, enough to wet the ground, from high-based cells last month with a concurrent temp of 41.8C on my weather station!
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Old 27-03-2016, 12:37 PM
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madbadgalaxyman (Robert)
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G'day there Les,

I really enjoyed reading your visual observations of A3574. Your explorations of this cluster must have been very enjoyable!

In my opinion, the various galaxy clusters and galaxy groups in Centaurus that are found at this considerable distance , are still largely 'unknown territory' for most observers, despite the remarkable nature of these distant galaxy-rich structures.

In case you missed it, there is an interesting discussion of IC 4329 and
IC 4329A and Abell 3574, in the Science forum:

http://www.iceinspace.com.au/forum/s...d.php?t=110009


Note especially my morphological notes on IC 4329 at the end of the thread;
- complex and unusual structure....it is not quite type S0 and not quite an elliptical galaxy
- IC 4329 is remarkably blue, compared to the typical elliptical galaxy
- there is a diffuse outer envelope which is not a disk, and which is of highly uncertain 3-D shape
- this galaxy has shells or steps in its outer light, the sign of previous galaxy merger activity

As a really serious student of galaxy morphology, I would be very interested in hearing about accurate observations of the very-centre/nucleus/nuclear-regions, of IC 4329 and IC 4329A, especially with very good optics and very good seeing!
(Personally, I think it is feasible that dust lanes might be visually observable in good seeing, near the centres of some elliptical galaxies, due to the high surface brightness.)

Much of the structural detail that I noted about the 'envelope' of I4329 is not observable by visual observers, but I would like to see really accurate descriptions of the centralmost regions of galaxies by visual observers.
Over the years, in IIS fora, I have posted quite a lot about the structure of the nuclear regions of galaxies, in order to give visual observers a "toolkit" which enables them to understand the various sorts of structures that can be observed near to the very centres of galaxies.

cheers,
Robert

One more interesting point that I would like to extract from the other thread is that the great Alan Sandage, a man who "almost knew galaxies in the face-to-face sense", was able to make good distance estimates of clusters of galaxies, using simple and easily-observable parameters such as the angular diameters and surface brightnesses of the member galaxies.
He did this to great effect in his monumental "Virgo Cluster Catalog" (= the VCC) , when he used the 200 inch at Mount Palomar to photograph the entire Virgo Cluster of Galaxies.
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Last edited by madbadgalaxyman; 27-03-2016 at 12:55 PM.
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