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Old 29-12-2010, 05:15 PM
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barx1963 (Malcolm)
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Fumbling in Fornax Observing Report 28/12/10

Well I made a very nice set of obs last night, lots of galaxies in the Fornax cluster and a couple of others. Finished the December challenge and finally got the Flame Nebula!

Hopefully no typos or errors for Les to pick up this time.


Observing Report 28/12/10


All observations made using Dobsonion mounted 305mm Newtonian reflector at f/5. Eyepieces use are 34mm Meade 4000(44x) 24mm Panoptic (67x) 13mm Nagler T6 (115x) or 13mm Nagler with Barlow (230x)

Charts - Uranometria 2000 (2nd ed.) Data derived from Uranometria (2nd ed) Deep Sky Field Guide.

Observations 28/12. Seeing good, transparency very good. Some Light Pollution as usual

NGC 1316 and NGC 1317 Galaxies in Fornax (December Challenge objects)
NGC 1316 RA 03 22 41.0 Dec -37 12 28 Mag(V)8.5 Dim’ 11x7.2 SB 13.2 Class SAB(s)0o Pec
NGC 1317 RA 03 22 44.6 Dec -37 06 11 Mag(V)11.0 Dim’ 2.8x2.4 SB 12.9 Class SAB(r)a

From Acamar (Theta Eridani) move about 4deg slightly N of f to a wide group of 4 mag 7 stars. A tight triangle of mag 7.5 and 8 stars lies just to f of this group. A pair of very faint stars 1deg to Nf point at targets. NGC 1316 is large and bright with an obvious core. Outer envelope is quite faint, however sky was not completely dark at time observed so may become easier to see later. NGC 1317 is obvious as a smallish patch on N side. Both easily fit within field at 67x and also at 115x. Higher power also makes outer envelope of both target (especially 1316) easier to see. No structure visible in either target.
Additional notes added post observation. NGC 1316 is lenticular and has been involved in galaxy mergers within relatively recent past eg within 100 million years. HST images show dark gas clouds very reminiscent of NGC 5128. I would be interested to hear if these have been observed visually. The comparisons with 5128 do not end there as this galaxy is also the location of a strong radio source, Fornax A. NGC 1317 is a tight spiral. Although it is considerably less bright than 1316 (11 against 8.5) it has a higher surface brightness making it very easy to observe.
Both objects were discovered by James Dunlop, NGC 1316 was his 548th entry and NGC 1317 was his 547th. Hartung lists the pair as number 87.
Greg Bradley has an excellent image at http://www.iceinspace.com.au/forum/showthread.php?t=67199&highlight=ng c+1316 (thanks to GlenC for mentioning this) which shows a part of the dark dust cloud just to the right of the bright nucleus. It also really clearly shows the tight spiral in 1317.

NGC 1336 Galaxy in Fornax
RA 03 26 32.3 Dec -35 42 49 Mag(V)12.3 Dim’ 2.1x1.5 SB 13.4 Class SA0-

From NGC 1316 as described above, a wide group of 3 mag 6 and 6.5 stars 1deg to Np (Chi Fornacis 1,2 and 3) target lies between 2 widest stars. Very faint and small, only revealed with averted vision at 67x, 115x improved contrast enough to make just visible with direct vision.

NGC 1365 Galaxy in Fornax (December Challenge object)
RA 03 33 36.7 Dec -38 08 20 Mag(V)9.6 Dim’ 11.0x6.2 SB 14.1 Class SB(s)b I

From the triple Chi Fornacis, move f and slightly S about 1.5deg. Target is visible at 44x as a faint haze. 115x reveals a very distinct core and envelope. 2 very faints stars on f edge. Some structure is suggested with a distinct brighter patch on N side.

Additional notes added post observation. Previously observed on 8/11/09 with similar results. Although this target is one of the grandest barred spirals in the sky (O’Meara states it is only surpassed by NGC 1300) its low surface brightness makes it hard to make out structure unless skies are exceptional. Listed by Dunlop as number 562 it is also notable as having been the sight of a visual supernova discovery in 2001 by Bob Evans. This is a very large galaxy with its bar alone measuring 94000 light years in length.

NGC 1380 Galaxy in Fornax (December Challenge object)
RA 03 36 27.6 Dec -34 58 35 Mag(V)9.9 Dim’ 4.0x2.4 SB 12.2 Class SA0

From NGC 1365 there are 2 mag 7.5 stars 30’ apart about 30’ to f. 2 wider brighter stars lie 1deg to N. Target lies half way between these. Quite small but fairly bright. Easily seen at 67x and very clear at 115x. Faint hints of structure.

Additional notes added post observation. Although I thought I saw some hints of structure, classification of SA0 I believe would indicate a non-barred lenticular which would make this highly unlikely. Listed as Hartung 94 who comments that it is a spiral?

NGC 1380A Galaxy in Fornax
RA 03 36 47.6 Dec -34 44 16 Mag(V)12.4 Dim’ 2.4x0.7 SB 12.8 Class S0o :sp

Lies 15’ to N of NGC 1380 and just to f of a mag 8.5 star. Small and faint.

NGC 1381, 1379 and 1387 Galaxies in Fornax
NGC 1381 RA 03 36 31.7 Dec -35 17 45 Mag(V)11.5 Dim’ 2.7x0.7 SB 12.0 Class SA0 :sp
NGC 1379 RA 03 36 04.1 Dec -35 26 31 Mag(V)10.9 Dim’ 2.4x2.3 SB 12.8 Class E
NGC 1387 RA 03 36 57.2 Dec -35 30 25 Mag(V)10.7 Dim’ 2.8x2.6 SB 12.7 Class SAB(s)0-

Group lies about 20’ S of NGC 1380. All three fit with FOV at 115x, very clear but small.

Additional notes added post observation. This group was a pleasant surprise to me. A very pretty grouping that should be accessible to most smaller scopes. Wonderful to see 3 galaxies within one FOV. I haven’t been able to find any references to this group, probably it is overlooked in favour of the larger brighter members of the Fornax cluster.

NGC 1374 and 1375 Galaxies in Fornax
NGC 1374 RA 03 35 16.9 Dec -35 13 36 Mag(V)11.1 Dim’ 2.5x2.3 SB 13.0 Class E
NGC 1375 RA 03 36 17.0 Dec -35 15 58 Mag(V)12.4 Dim’ 2.2x0.9 SB 13.0 Class SAB0o:sp

Lies 25’ to Sf of NGC 1380. Tight pair of galaxies that appear to be interacting. Given that there is no distortion of an otherwise standard elliptical in 1374, it would appear to be a chance alignment.

NGC 1399 Galaxy in Fornax
RA 03 38 29.7 Dec -35 26 53 Mag(V)9.6 Dim’ 6.9x6.5 SB 13.7 Class E1 pec

Mag 7 star which is f star of pair of brighter stars described above as bracketing NGC 1380. Target lies 15’ approx to S if this. Very bright core, envelope appears large but is quite hard to detect.

Additional notes added post observation. Class E1 indicates very little flattening, indeed John Herschel when he discovered this object originally classified it as a globular cluster and original NGC entry did also. Although this is the brightest Fornax Cluster object, it has a quite low surface brightness (13.7) making much other than the core hard to detect. O’Meara comments that he is entirely unable to tease any structure out of this galaxy or its nearby companion NGC 1404 (described below). He also gives a visual magnitude of 8.8 which is considerably higher than the U2000 Deep Sky Field Guide listing above of 9.6.

NGC 1404 Galaxy in Fornax
RA 03 38 51.7 Dec -35 35 40 Mag(V)10.0 Dim’ 3.3x3.0 SB 12.5 Class E1

A mag 8 star lies 15’ SF from NGC 1399. Target is just next to it. Core appears similar in size to NGC 1399 but fainter. Appears to have some mottling. A very faint mag 12? Star appears on edge of galaxy.

Additional notes added post observation. As mentioned above O’Meara notes no structure and this would be consistent with a very plain elliptical such as this. Mottling I observed is probably just an effect from nearby mag 8 star.

NGC 1487 Galaxy in Eridanus (December Challenge object)
RA 03 55 44.8 Dec -42 22 04 Mag(V)11.9 Dim’ 2.4x1.7 SB 13.3 Class pec

Very faint (listed as mag 11.9) appears to have 2 foreground stars and some mottling

Additional notes added post observation. Discovered by Dunlop and listed as number 480. GlenC has an excellent post at http://picasaweb.google.com/dunlop1826/Dunlop28#5356128738040618578 which clearly shows the peculiar nature of this galaxy as well as the 2 faint foreground stars I mentioned. Dunlop and J Herschels notes also mention these stars.

NGC 2024 Emission Nebula in Orion The Flame Nebula
RA 05 41 54.0 Dec -01 51 00 Dim’ 30x30 Type E BC 2-5 Colour 3-4

Large and very faint just f of Alnitak. Nearly fills FOV at 115x. Dark lanes are very obvious and clearer with Nebula filter.

Additional notes added post observation. BC in the data above refers to the brightness of the object 1 being the brightest and 6 barely detectable. A range indicates that it will vary depending on conditions. The range 2-5 indicates that this object is easily detectable in very good seeing and very difficult in poor visibility. This confirms to my experience as I have tried for this object many times and only on this night did I achieve success.


Malcolm
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Old 30-12-2010, 10:17 AM
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ngcles
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Hi Malcolm & All,

Congratulations on an excellent report mate!

Next time you go back use a bit more magnification on NGC 1365 and have a closer look for the sinewy, filamentary arms that trail-off to the NE and SW from the bar. I have seen them several times in 25cm in a "nearly-dark" sky. I'd suggest about x150 (or a 2mm exit pupil) in your 'scope. There are several observing reports I'm inclined to trust that indicate they are visible in 20cm and even 15cm at true dark-sites.

I disagree with O'Meara (what else is new) about ranking it behind NGC 1300. The latter is superb photographically but it is somewhat harder to see spiral arms in than NGC 1365. Spiral arms are visible in 46cm in NGC 1300 but not as good as NGC 1365.

Close-by to NGC 1374 + -75 is NGC 1373. It is about 5' NW of -74. I can still remember seeing this one for the first time nearly 20 years ago when it became my "faintest galaxy seen" record holder at that time. Has a true visual mag of V13.3. That's why I've got a soft-spot for it. Have a look for it too.

Love NGC 1381 too -- it has that classical "flying saucer" shape and looks just like the photo in 46cm. NGC 1380A is very similar but fainter than NGC 1381 and IC 335 further northward is similar again. NGC 1380, -80A, -81 and IC 335 are all S0 type lenticulars that are common in large, massive clusters of galaxies. Used to be spirals once-upon-a-time, but have had the gas and dust torn and knocked out of them by repeated interactions with other large galaxies or via RAM pressure with gas in the intra-cluster medium (that has already been torn out of other galaxies). Large galaxy clusters are rather violent neighbourhoods ...

There was an interesting article on this the other day actually:

http://www.naoj.org/Pressrelease/2010/11/09/index.html

where they found large clouds of ionised Hydrogen streaming out of galaxies and between galaxies in the Coma Cluster (AGC 1656). It would be interesting to see a 21cm radio map (cold Hydrogen) of The Fornax Cluster .

No doubt it's been already done but now I've thunk it, I've gotta go look for it ...


Best,

Les D
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Old 30-12-2010, 11:26 AM
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barx1963 (Malcolm)
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Thanks for your kinds words Les
I was having quite a bit of trouble teasing out any detail in 1365, I think light pollution, while not drastic is still a significant factor in my backyard observing. Last night I had a crack at NGC 1300 to see if I could offer any opinion as to the relative merits of 1365 vs. 1300 and could really only make out the core and a bit of the bar. Also had a look at PN NGC 1360 which was invisible except for the central star until I pout in the OIII filter. All this indicates to me that the LP is a prob for these objects.
I did have a quick crack at 1373 but it was not visible.
I will post a report shortly on last nights viewing.
Thanks again

Malcolm
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Old 30-12-2010, 01:34 PM
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ngcles
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Hi Malcolm,

NGC 1360 is one of the few examples of a "high-excitation" PNe. Though most PNe emit quite a bit of OIII (doubly ionised oxygen) when young (drops-off as they age and the nebula expands away from the PNn) NGC 1360 is an exceptionally strong emitter and an OIII or UHC has a very dramatic effect. Fairly close by (about 200-odd pc), bright PNn (central star) and youthful means its a pretty easy object.

http://www.astrosurf.com/antilhue/ngc1360.htm

Best,

Les D
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Old 01-01-2011, 11:50 AM
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Paddy (Patrick)
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Nice report as always Malcolm. And thanks for the post observation notes - very interesting.

Les, I definitely agree with you that 1365 is a better object for visual observing than 1300. Heaps of detail visible in the arms of 1365 with dark skies.
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