Omega Centauri vs 47 Tucanae

m11 (Mel) · #1 02-02-2016, 03:52 PM

Hi All,

My understanding is that Omega Centauri GC is larger and brighter than 47 Tucanae GC. When comparing both from dark site and urban skies seems to show 47 Tucanae as coming out as brighter.
Not sure if its just my perception or my telescope .

Does anyone have a similiar view?

Mel

Atmos (Colin) · #2 02-02-2016, 04:15 PM

I am going to guess that it is likely due to where they are in the skies at the moment. This time of the year Omega Centauri is likely to be lower to the horizon than 47 Tuc and that will make it appear dimmer, looking through more atmosphere, potentially more light pollution as well depending on where you are.

m11 (Mel) · #3 02-02-2016, 04:29 PM

Hi Colin,

Thanks for replying. Will need view at later in the night or wait later in the year.
So I assume you see defintely see Omega Centuri as brighter?

Thanks,

Mel

Atmos (Colin) · #4 02-02-2016, 04:34 PM

To be honest I have never really noticed, there is only about 0.3 mag brightness between them, Omega Centauri being bigger and brighter.

m11 (Mel) · #5 02-02-2016, 04:41 PM

No problems, thanks for replying.

Just noticed that many people who have viewed with me say the same thing, that 47 Tucanae is brighter.

Will wait until Omega Centauri is higher as you suggest and view again.

Thanks,

Mel

barx1963 (Malcolm) · #6 02-02-2016, 05:51 PM

Overall, Omega Centauri is brighter. The U2000 field guide lists its visual magnitude as 3.9 while 47 Tucanae is listed at 4.Ihave read elsewhere of larger differences.
The key thing is that 47 Tucanae is far more compressed so appears much brighter. In a decent sized scope, 47 is much more interesting viewing as Omega is just so spread out.

Cheers

Malcolm

bigjoe (JOSEPH) · #7 02-02-2016, 06:12 PM

Hi Mel.

I find I need to wait for Omega to rise higher in the sky compared to TUC 47, otherwise it can be quite unimpressive in comparison.

The core of TUC 47 always seems to be much more intense; just loverly.

bigjoe

m11 (Mel) · #8 02-02-2016, 07:59 PM

Hi Malcolm,

Thank you for the explanation. It makes alot sense. 47 Tucanae has always been my favourite GC
Both are lovely GC and we are lucky to have both.

Mel

m11 (Mel) · #9 02-02-2016, 08:34 PM

Quote:

Originally Posted by bigjoe

Hi Mel.

I find I need to wait for Omega to rise higher in the sky compared to TUC 47, otherwise it can be quite unimpressive in comparison.

The core of TUC 47 always seems to be much more intense; just loverly.

bigjoe

Hi Bigjoe,

I just need to wait a bit later to view it seems. It just seemed to me alot dimmer and I have been wondering why when i compare both.

I love the intense core of 47 everytime, it blows me and everyone I show away.
Thanks again for responding and giving a logical explanation

Everyone has been really helpful

Mel

pdalek (Patrick) · #10 02-02-2016, 08:46 PM

The surface brightness of the core of 47 Tuc is higher than that for Omega Cen. However it drops faster with radius.
From high LP sites the high core brightness makes 47 Tuc stand out. From dark sites the greater size of Omega Cen dominates.

A good paper comparing the two
http://arxiv.org/pdf/1305.6025v1.pdf

m11 (Mel) · #11 02-02-2016, 10:15 PM

Hi Pdalek,

Thanks for the link on GC and explaining the differences between both GC.Will need to spend time reading it and hopefully understanding it.

Appreciate everyone being so helpful

Mel

uwahl (Ulrich) · #12 02-02-2016, 11:51 PM

I observed Omega Centauri at 400x with a 10 inch scope at a dark sky site with 20% humidity and a very steady atmosphere in western Queensland last year. The core stars were rock steady. Now that was impressive.

I have never before or since been able to do that but as I have only been observing for two years I live in hope.

m11 (Mel) · #13 03-02-2016, 02:31 PM

Hi Uwahl,

Agree with you , its those moments you always remember and hope to replicate again.

Mel

The_bluester (Paul) · #14 03-02-2016, 03:01 PM

Yeah those exceptional observing moments are memorable aren't they. One of my best nights was at an ASV Messier star party and for about half an hour (I think, felt like all night and also like ten seconds, all at the same time) I had awe inspiring views of Saturn at around 430X. Never before and never since. I was just transfixed until the seeing deteriorated again.

On the glob topic, I have always found 47 Tuc my personal favourite, probably for the reasons described above it just seems to carry more WOW factor for me. It is a bit like that first glimpse of the Orion nebula for the season, an old friend, but for 47Tuc it is like that every night.

We have an astro night planned at home for this Saturday and I can safely assume the scope is going to spend quite some time aimed at 47 Tuc, despite the fact it will be less than ideally placed.

bigjoe (JOSEPH) · #15 03-02-2016, 03:48 PM

Yes 47 Tucanae; straight up near the zenith one night in winter at my house in Concord, Sydney in a 7" Mak , the view was as memorable as the view in a 10" SCT at my property at Castelreagh near Penrith!

You just never forget those moments!

bigjoe.

MattT · #16 03-02-2016, 08:25 PM

Both best observed with Binoviewers IMO...both give the 3D effect. Have spent hours with 30mm plossls a 1.6x barlow on a 6" f8 frac and 10" f4.8 Newt.....beautiful.

johnnyjetski (John) · #17 03-02-2016, 08:31 PM

Very Interesting thread everyone!

47 Tucanae for me is one of the most amazing sights in the southern sky.
I never cease to enjoy looking at it and imagining what it would be like being closer to an environment like that.
It fires up my imagination and hopefully others when I show it through my scope.

JohnS

bigjoe (JOSEPH) · #18 03-02-2016, 08:41 PM

Quote:

Originally Posted by MattT

Both best observed with Binoviewers IMO...both give the 3D effect. Have spent hours with 30mm plossls a 1.6x barlow on a 6" f8 frac and 10" f4.8 Newt.....beautiful.

Hi Matt.

I must put a Binoviewer on my to buy list and try it in a 10" sct I have; I think i'll be in for a wonderful surprise!

cheers bigjoe.

m11 (Mel) · #19 03-02-2016, 10:52 PM

Hi Matt,

Never thought of a Binoviewer to view these beauties in particular. Does the Binoviewer enhance the view in other ways as well?

Wondering if its worth getting a binoviewer and what objects really stand out in particular with them?

Thanks,

Mel

m11 (Mel) · #20 03-02-2016, 10:57 PM

Was going to add, thanks to everyone who have responded. I am very new to astronomy and found everyone so helpful.

I didn't expect so many people willing to impart their knowledge and take time out to reply.

My sincere thanks

Mel