Centaurus A, where are you?

[Screwdriverone]

Hi All,

Something that bothered me a lot last night was the fact that for the life of me, I could NOT see Centaurus A in any shape or form.

I tracked along from Omega Centauri and even lined up with mu Centauri and still no luck. I must have spent 45 mins looking for something bright in the region on the charts and nada.

Considering that I could spy the Sombrero shape of M104 earlier and that the seeing was phenomenal, is there a trick to finding this Galaxy? I used the whizzbang excel chart and my starhopping book and all the things I could think of and nothing!

I was trying to find it at 80X with my 12.5mm ED which showed the globular omega centauri at a brightness I have never seen before and it was resolving into stars even on my small scope, so to be unable to find Centaurus A was very disappointing.

My name is Chris and I have a problem....

Please help :sadeyes:

[goober]

Welcome to 5128 anonymous.

It can be a tricky beast, I usually just plough across from Omega Centauri until I bump into it, but sometimes I get lost and sometimes I just don't see it at all. The last 2-3 times I've tried, it's been fantastic.

Three starting suggestions....

1. Across from Omega Centauri exactly half way to Iota Centauri.

2. Mu Centauri, then four degrees west.

3. When I'm really struggling, I find n Centauri (5th magnitude star), and starhop a staircase of magnitude 6-7 stars south east. Jump off at the bottom, go about a field of view further, and it should be there.

Look for a hazy faint glow. It doesn't jump out at you, it sort of grows :)

[Screwdriverone]

Thanks Doug,

Exactly what I needed, a quick fix of experience.
Of course, the first one is always free, just to get me hooked.!

Thanks again, I will try and pinpoint this sucker asap.

Cheers

Chris

[GrahamL]

hi

a quick sketch.. find omega cent draw a line from the bright stars top and bottom..from omega cent project another perpendicular out to the
bright star pictured right ..cent A is fairly close to were I've marked it there i think.

[goober]

I've tried to attach a finder chart with the star hop from n Centauri highlighted. It's not the greatest star to start from, but once found the chain is easy to navigate. When you get to the pair of the stars at the bottom of the "stair", make a 90 degree turn. You'll see a star about half way to NGC 5128. Go as far again and look for a faint glow.

The left/right, up/down may be reversed, depending on your scope.

Light pollution tends to blot this one out.

[peter_4059]

I draw a triangle from Omega Can to Mu Cen to Cent A. Follow up the right hand side of the small triangle of stars to the left of Omega Cent. In the attached the red oval is Cent A. The blue circle is Omega cent.

[Screwdriverone]

Thanks Peter Doug and Nightstalker,

I think the light pollution could have been the issue as the omega centaurus is a fairly bright globular which you cant miss, but this one is a bit more diffuse and with the background Milky Way, blends in.

I will try everywhich way and fingers crossed.

Thanks

Chris

[ngcles]

Hi Chris,

I notice you are using an equatorial mount and I've got an (pretty easy)alternative method that you might also want to try.

If you take a look at a map, you will notice Omega Centauri (NGC 5139) and Centaurus A* have very similar values for Right Ascension. Centaurus A* is about 1 minute of RA west of Omega Centauri and therefore they lie almost exactly North-South of each other 4.4 degrees apart (about 4 to 5low-power eyepiece fields apart).

Your mount won't need to be aligned on the pole accurately, so long as the polar axis is within a few degrees of the SCP.

Locate Omega Centauri in a low power eyepiece, but don't centre it. Instead place Omega Centauri in the far eastern side of the eyepiece field and then continuing to look through the eyepiece, use the dec slow-motion control to move the 'scope north by 3.5 degrees in declination and Centaurus A* should be centred. That journey is about 4 or 5 low-power fields (count them as you go).

Though Centaurus A* is a bright galaxy, being spread over a large area it's sufrace brightness is somewhat lower. It will appear in a 5" 'scope less than 1/4 the diameter of Omega Centauri and a lot fainter.

Hope this helps, good luck and let us know how you go.

Best,

Les D
Contributing Editor
AS&T

[Screwdriverone]

Great info, thanks Les,

I will try this out with my brand spanking new UHC-S High-transmission Nebula filter 1.25" I just got from Andrews Comms.

Did I already mention how good these guys are for advice and price? Oh well, I am gunna tell you again.:thumbsup:

Can't wait to try this out and see if I can locate Centaurus A..

Wish me luck

Chris

[ngcles]

Hi Chris,

No, No, No! Nebula filters are not for galaxies, they're for ... well nebulae. They will give a considerable contrast boost to most emission nebulae and nearly all PNe because they shine by the emission lines that the filter passes. But won't help a galaxy -- in fact it will get dimmer because galaxies are mainly made of stars and a UHC will block a lot of starlight. Use the filter, even on a bright galaxy and it will get even harder to find (probably invisible actually).

Hang on to that filter for things like M42, or Eta Carinae (NGC 3372), but keep it firmly in the eyepiece box for any galaxy!

Best,

Les D

[Screwdriverone]

Ahhh, yes, see, there is the newbie factor coming out in me again.....

Thanks for the correction, I have been so carried away researching filters and goto's and DSC, that I lost the plot on what would do what.

It IS the nebulae that I want to see more than anything, so with this in mind, the UHC -S will be the best for this?

Also, will it show up more or less details on the planets?

Have I confused this filter with an OIII or a DGM Optics NPB filter?

Alternatively, which then is the best overall choice for improving details on planets, nebs and clusters (contrast or otherwise)?

Perhaps I have been hasty in my purchasing (not the first time)

Chris

[taminga16]

Chris,
NGC 5128 is a tough target, not as bright as one would expect and easy to pass over because it is not what you think that you are looking for,
have a scout around with your Bino's and then zero in starting with low mag and then up the power a little once you get around what it is that you are viewing. (look for the dark band, not the brightness).

The other blokes are spot on in saying that the object does not leap out at you but grows as you look.

Good Luck, We will wait for your results.

Greg.

[CosMos]

This article may help to identify NGC 5128 and some surrounding galaxies (need dark sky). Have included 2 other articles to pave the way to other galaxies

http://www.astronomy.org.nz/aas/Journal/HeartOfTheCentaur.asp

http://www.astronomy.org.nz/aas/Journal/CosmosMonthly/Sculptor.asp

http://www.astronomy.org.nz/aas/Journal/Oct2004/GreatGalaxyGrab.asp