Has anyone ever seen the "Forcade-Figuroa' Object?

[§AB]

I've been hunting for this galaxy for ages, and have NEVER seen it. On SIMBAD it is shown as an impressive looking edge on galaxy, sort of like NGC 4945. It is located just to the northeast of omega Centauri, catalogue no: ESO 270-17.

Anyone successfully hunted this down?

[astroron (Ron)]

Originally Posted by §AB

I've been hunting for this galaxy for ages, and have NEVER seen it. On SIMBAD it is shown as an impressive looking edge on galaxy, sort of like NGC 4945. It is located just to the northeast of omega Centauri, catalogue no: ESO 270-17.

Anyone successfully hunted this down?

I have observed this object on a few occassions with my 16" but it is very difficult as it is very faint , and there is a star which in front of it which makes the it even harder to observe.
You need a dark clear sky and good seeing to observe it.
This was galaxy mentioned in the Amastro observing site a few years ago and I took up the challenge to find it
There are a number of faint but observable (in larger telescopes) ESO galaxies in the vercinity of NGC5128.
Image of ESO 270-17.
Ron

[Rodstar (Rod)]

Andrew Murrell was talking about that object the other day. I think he said he has seen it with Hector. I have only tried to see it once in The Mary Rose (from my backyard) and could not find it. Will try again under dark skies.

[ngcles]

Hi §AB & All,

Yes, it is certainly observable.

I stumbled up on this thing about 10 years ago while cruising around in the Megastar (v4.0? back then) software looking for things to look at and marked it for attention.

My first observation (confirmed by G Mitchell) was under a pristine Mudgee Star Party sky in 2000 with my then 31cm. These are the notes:

x186, x156, x131

Mag 11.7 Size 11.5' x 1.4'. Confirmed by G Mitchell. An Extremely !! Faint eg of very very LSB but quite large. In a pretty *ry field as an ill defined streaky, almost non-existent patch of weak gossamer 6' x 1' in PA 110 with a line of *s not superimposed but running beside it mags 10-11. Does not grow to the axis or the core. Very very difficult object.

I have also showed it to Steve Gottlieb (who writes for Astronomy Magazine, formerly of S&T) in 2001 using my 31cm from a pristine site and he confirmed as well.

I have since observed it many times with 46cm where it is a tad brighter but not much bigger or more detailed.

I'm pretty certain Andrew Murrell (Hector) has seen it too (and probably several if not many other advanced Australian observers).

Though it is commonly referred to as a galaxy, it is *not* a galaxy per se. Rather it is a non-rotating coreless shred of stars. A bit like a dismembered limb. There is a 1995 (I think) paper that relied upon a supercomputer simulation regarding this interesting object. If I get a chance in the next day or so, I'll dig it up.

(From my memory of the paper) It seems that one of the possible scenarios that could eventuate from a collision (at a "just right" speed / angle) between Centaurus A* and a fair-sized spiral is a fully supported and rotating girdle of gas, dust and stars around Cen A* plus the core/nucleus of the spiral is ejected plus one or more spiral arms are ejected at high speed.

This simulation actually fits reasonably well with what is observed. ESO 270-17 (a former arm??) is proximate to Centaurus A* (though its re-shift is certainly higher than Centaurus A*)(speeding away from the scene??) while a small peculiar blue compact/elliptical galaxy is also present nearby -- NGC 5237 (the former core/nucleus??).

This is _not fact_ but hypothesis -- but it also explains a lot of peculiar things about these three objects pretty neatly.

BTW, I remember this subject coming up in a discussion between myself another observer (_very_ experienced, but remains nameless) about three years ago in November.

We were having a long, long chin-wag about things seen/hope to see and that person asked about ESO 270-17. I said I'd seen it, and they _flatly_ refused to accept my observation and harrumphed that it was "impossible". The individual was even more surprised when I said I'd seen it (at least twice) in 12". Gary Mitchell was there and confirmed the observation "in person"

"Impossible" -- "don't believe it" -- "can't be seen -- never ever -- not even in 18" they maintained.

Well, as a result, we had a wager (port I think it was) -- that the following year I'd show it to them in my 18" 'scope. April came 'round, so did the person to Mudgee. We dialled it up on the Argo, did the slew and within 10 seconds I had a concession. The transparency on the night was very good, the seeing poor and it was only at 40 degrees elevation.

I also covered it in some detail in a talk I did at the SPSP (2004?? 2005 ???) as part of the Centaurus A*/M83 cluster and I had hoped to cover it in an upcoming Deep Sky Delights article -- probably Feb-March or April next year or the one after.

Have a got at it §AB. It is near/at the limit of detection for 12" under a perfect sky. Let us know how you go.


Best,

Les D
Contributing Editor
AS&T

[ngcles]

Hi §AB & All,

This is the paper I mentioned above.

http://articles.adsabs.harvard.edu/c...;filetype=.pdf

Best,

Les D
Contributing Editor
AS&T

[seeker372011 (Narayan)]

love this thread..even though i have no hope with my 10 inch from my backyard

[wavelandscott (Scott)]

Seen it?!?! No, I am not sure I can even pronounce it!

[§AB]

Originally Posted by ngcles

Hi §AB & All,

Yes, it is certainly observable.

I stumbled up on this thing about 10 years ago while cruising around in the Megastar (v4.0? back then) software looking for things to look at and marked it for attention.

My first observation (confirmed by G Mitchell) was under a pristine Mudgee Star Party sky in 2000 with my then 31cm. These are the notes:

x186, x156, x131

Mag 11.7 Size 11.5' x 1.4'. Confirmed by G Mitchell. An Extremely !! Faint eg of very very LSB but quite large. In a pretty *ry field as an ill defined streaky, almost non-existent patch of weak gossamer 6' x 1' in PA 110 with a line of *s not superimposed but running beside it mags 10-11. Does not grow to the axis or the core. Very very difficult object.

I have also showed it to Steve Gottlieb (who writes for Astronomy Magazine, formerly of S&T) in 2001 using my 31cm from a pristine site and he confirmed as well.

I have since observed it many times with 46cm where it is a tad brighter but not much bigger or more detailed.

I'm pretty certain Andrew Murrell (Hector) has seen it too (and probably several if not many other advanced Australian observers).

Though it is commonly referred to as a galaxy, it is *not* a galaxy per se. Rather it is a non-rotating coreless shred of stars. A bit like a dismembered limb. There is a 1995 (I think) paper that relied upon a supercomputer simulation regarding this interesting object. If I get a chance in the next day or so, I'll dig it up.

(From my memory of the paper) It seems that one of the possible scenarios that could eventuate from a collision (at a "just right" speed / angle) between Centaurus A* and a fair-sized spiral is a fully supported and rotating girdle of gas, dust and stars around Cen A* plus the core/nucleus of the spiral is ejected plus one or more spiral arms are ejected at high speed.

This simulation actually fits reasonably well with what is observed. ESO 270-17 (a former arm??) is proximate to Centaurus A* (though its re-shift is certainly higher than Centaurus A*)(speeding away from the scene??) while a small peculiar blue compact/elliptical galaxy is also present nearby -- NGC 5237 (the former core/nucleus??).

This is _not fact_ but hypothesis -- but it also explains a lot of peculiar things about these three objects pretty neatly.

BTW, I remember this subject coming up in a discussion between myself another observer (_very_ experienced, but remains nameless) about three years ago in November.

We were having a long, long chin-wag about things seen/hope to see and that person asked about ESO 270-17. I said I'd seen it, and they _flatly_ refused to accept my observation and harrumphed that it was "impossible". The individual was even more surprised when I said I'd seen it (at least twice) in 12". Gary Mitchell was there and confirmed the observation "in person"

"Impossible" -- "don't believe it" -- "can't be seen -- never ever -- not even in 18" they maintained.

Well, as a result, we had a wager (port I think it was) -- that the following year I'd show it to them in my 18" 'scope. April came 'round, so did the person to Mudgee. We dialled it up on the Argo, did the slew and within 10 seconds I had a concession. The transparency on the night was very good, the seeing poor and it was only at 40 degrees elevation.

I also covered it in some detail in a talk I did at the SPSP (2004?? 2005 ???) as part of the Centaurus A*/M83 cluster and I had hoped to cover it in an upcoming Deep Sky Delights article -- probably Feb-March or April next year or the one after.

Have a got at it §AB. It is near/at the limit of detection for 12" under a perfect sky. Let us know how you go.


Best,

Les D
Contributing Editor
AS&T

Interesting summary there Les. So it is actually a rogue shred of stars , the remnant of a possible collision, so then this object doesn't fall under any existing category of DSO. Sounds like a real tough observing challenge here!

[TrevorW]

Try saying that fast 5 times seen it nope!! trying to pronouce it's hard enough

[gary]

On Saturday 25th Feb 2012 at around 02:45 AEDT, Andrew Murrell brought
"Fourcade-Figueroa shred" to my attention when he dialed up ESO 270-17 on the
Argo Navis and we then allowed this object's photons to strike the mirror of the 30" f/4.5
SDM Dob which was set-up on the dark-sky lawns of the Warrumbungles Mountains
Motel at Coonabarabran.

The 30" of aperture made short work of it and my first thought was that I was looking
at just another edge-on galaxy until Andrew explained that it was part of the shredded
disk of a galaxy that had been in an interactive tussle with Centaurus A. That
explanation shone a whole new light on this remarkable object.

The first thing that strikes you then is that it is quite a way from it to Centaurus A.
However, it has had plenty of time to get to where it currently is. In the paper
that Les cited it is estimated that the interaction took place 500 million years ago.
When something this catastrophic happens to your galaxy, you could also probably
count on it happening first thing on a Monday morning as soon as you sit down to work.

Les recounts the story of winning a wager as to whether it is viewable in an 18",
so that alone should encourage more observers to give it a shot. Otherwise,
the next time the 30" comes to Ilford or a star party you are attending, ask
Lachlan or one of us to dial it up.

While you are at it, also make sure you get to have a look at the Sombrero through the 30".
The view is to die for.