Ob Report

ZeroID (Brent) · #1 25-10-2010, 08:15 PM

Did some work to the 10" today. Replaced the finder scope with the red dot unit, rebalanced it, fitted a glare sheild opposite the focusser. Couldn't find a suitable ground target to align the red dot so had to wait till Jupiter came over the trees. Aligned and played with EPs and the barlow on Jupiter. Seeing was about 3 and transparency about 2. We've had some weird weather over here giving us static cloud mists up high.

Most of the easy clusters etc are dissappearing over my western horizon so targets a bit scattered so had a go for 47 Tuc. My compass alignment and leveling seems quite good because the setting circles put me very close to target. A few sweeps with the 20mm and I found a fuzzy ball. Barlowed it and got a bigger fuzzy ball with a denser core area. I could not separate the inner group from the outer 'ring' but I could find no other sizeable cluster in that region so I am assuming I got the right cluster. I managed to find it with a 2 x barlowed 12 mm but definition and brightness was very reduced although the cluster almost filled the view at that mag, 228 ?

Anyone able to confirm what I saw ? I expected more but as I said LP and mist were not helping and it's not my best sky direction.

Paddy (Patrick) · #2 26-10-2010, 11:04 AM

Hi Brent,

I would have expected you to see quite a bunch of resolvable stars with 47 Tuc, but perhaps if transparency was poor that might be the reason. NGC 362 is another sizeable GC in that area - not as big or bright as 47 Tuc and fewer resolvable stars. I would think that at 200X assuming your scope is f6 that 47 tuc would more than fill your field of view but sprawl way beyond it.

The problem with using a red dot finder alone is that the view is not magnified and I find it can be hard to find exactly what I"m looking for. So I have both a red dot finder and a magnified 8x50 finderscope on my scope. I use the first to point the scope in the right direction and if what I want isn't in the FOV I can use the magnified finder to get it on the target. This is very useful for harder to find targets when I need to use little patterns of stars to get the target - the (corrected view) magnified finder shows them very well.

It will be interesting to hear your reaction when you do get on to 47 Tuc with clear skies. You will have no doubt about what you've seen.

mental4astro (Alexander) · #3 26-10-2010, 11:51 AM

Hi Brent,

First light for my 10" f/5 diy dob was 47Tuc with a 35mm EP. My first reactions was: "Holy crap..." (then peed myself).

That was from inner Sydney too.

You may well have been seeing one of the many and much smaller GCs that lurk in the same patch of sky as 47Tuc. Your 114 scope will also show a blaze of stars larger than the full moon in size.

If I'm lucky I can just make out 47Tuc naked eye from home. In binos it is also unmistakeable.

I'd suggest you still use a pair of binos for now. I have a RSF plus magnifiying finders. If I'm after something large, like 47Tuc, the RSF is all I need. In a dark site, or with faint objects without many stars to help with star-hopping, a maginfied finder helps. You may still need to iron out some alignment issues with your setting circles.

Here is a challenge for your scope. Once you've nailed 47Tuc, try finding the three other GCs that lie within its circular boundary,

. Here is a post of astrorons on the topic very relevant to you:

http://www.iceinspace.com.au/forum/s...5&postcount=14

Alex.

Suzy · #4 26-10-2010, 04:23 PM

Hi Brent,
In my 10" at F/5 I use a Pentax XW 10mm wide angle ep (70deg). I love the wide view at high mag, especially on those globs. You can get the whole glob into the fov with that high magnification. I agree with what the rest have said about putting that finder on. I took mine off in replacement of a red dot finder, but I am missing the help that the extra mag in a finder will help me, so i will be putting it back on along with my red dot finder.

Doesn't sound like 47 Tuc to me as it is fairly easily resolvable (a nice dense, but loose cluster). I wonder if you got Omega Centauri? The biggest glob there is. That one has got a very dense core. You being in NZ, it should be higher up in the sky for you than it is for us at the moment (I think). Tuc tends to have more trails of stars at the bottom of the glob (giving the glob an elongated look) whilst Omega Centauri tends to be very round. From what I've observed anyway.

I have to agree with what Alexander said about first seeing 47 Tuc...

Quote:

Originally Posted by mental4astro

Hi Brent,
First light for my 10" f/5 diy dob was 47Tuc with a 35mm EP. My first reactions was: "Holy crap..." (then peed myself).
Alex.

But I'll change my response to: "My goodness me, oh my", (then crossed my legs).

ZeroID (Brent) · #5 26-10-2010, 07:37 PM

Hmmm, dang ! Better get the bins out and have another looksee. I obviously did not get 47 Tuc from what you all say. NGC 362 maybe ? Stellarium shows a few clusters around there but all quite small and loose. I'll try again ... tonight, it's quite clear out there.

I'm trying to build a slightly bigger aperture finder. These little 8 x 24 plastic thingies are useless. Looking for a f6-8 50 mm or something. I've got one but it's embedded in a big lump of aluminium from a projector and weighs a ton so that is out. Shame because it's a nice lens combo. If I had a bigger lathe I'd spin it out. Something will turn up.

> Paddy - 10" f5

Paddy (Patrick) · #6 26-10-2010, 09:23 PM

Have fun Brent. With the tight core that you noted its very likely 362 as its a very concentrated GC, quite like 47 Tuc in that way but about 1/2 the size. Still a stunner in good conditions.

ZeroID (Brent) · #7 26-10-2010, 09:24 PM

Ok, pretty sure I am getting it. I have a 'shopping trolley' of what appears to be HIP 1651 and HIP 2186 plus 2 unidentified stars below giving a shopping trolley basket shape. (Stellarium ).
My setting circles seem to put me pretty close to the RA/Dec numbers in Stellarium although I hadn't levelled the base. It was just grab and go at the last minute.

But still not very bright or big although I am putting that down to LP in that region. There are not many bright marker stars to navigate from.

Quite a distinct core with a lot of stars. My 12 mm seems to give best result and averted vision lets me pickup a lot of peripheral stars. I think I am being misled by the very distinctive image Stallarium puts on it. It is certainly quite a dense group and looks more like Astrorons photo (thanks for the link Alex). I also spotted another smaller cluster nearby but not being sure about 47 Tuc I wouldn't hazard a guess as to ID.

More work to do obviously. I'm getting there one cluster at a time.

mental4astro (Alexander) · #8 26-10-2010, 10:37 PM

Hi Brent,

Here is a link to a chart that will help. 47Tuc is also known as NGC 104, and lies just north, or above, Beta Hydus:

http://www.geocities.jp/toshimi_taki.../1s_050129.pdf

The above chart comes from a good starters atlas which is best printed on A3 paper:

http://www.geocities.jp/toshimi_taki/index.htm

Stellarium is fine, but in the field I still find a printed chart and red light torch more practical. Binos also help.

At 10pm local time, 47Tuc is due north of Beta Hydrus.

ZeroID (Brent) · #9 27-10-2010, 06:48 AM

Binos (10 x 50) could not see it, LP kills most of my view in that direction.
I'll pull some charts down to confirm (or otherwise).
I can print A3 no problem.

EDIT: Just printed chart and yep, I got it. Recognised the surrounding star pattern as my 'Trolley Basket'.
Shows you how bad te LP is. I will attempt it again at my dark site when I get a chance, I want to see it in all it's glory.