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Viewing globular clusters


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I am a newbie and would appreciate some advice on viewing globular clusters. .  I view from Wisconsin, USA which is at 43 degrees latitude.   I am using an Orion 6in f/5 (FC750) Newtonian reflector telescope mounted on a SkyWatcher AZ4 mount.  I have upgraded the 25mm and 10mm Plossl eyepieces that came with the telescope with TeleVue 18.2 Delite and TeleVue Nagler 5 eyepieces.  I have had good views this summer of Jupiter, Saturn, Mars and the Moon and now want to move on to globular clusters

Since I currently have a good view of Scorpius, I have been trying to visualize globular cluster M4 using Antares as my initial target.  Antares currently sits at 28’ 51’’ so am looking through quite a bit of atmosphere.  Using Stellarium as my guide in walking from Antares, I am able to see, what I think is, the vague, hazy and very dim outline of M4 - not any way near the brightness shown me by Stellarium using the ocular view feature with the parameters of my telescope and eyepiece (normally the 18.2 Delite) plugged in.

So my questions (thanks for your patience in reading thus far):  Do you have any suggestions of how I might enhance the brightness and resolution of the stars in M4.  Is there simply too much atmosphere for me to look through to expect a better view?  Is there a filter that might be helpful?  I am normally viewing within 6o minutes of sunset when I see a sky full of stars.  Do I need to wait an hr or two, for more complete darkness?  Other suggestions?  Are my expectations too great under my viewing conditions?  Is there more a accessable cluster for me to cut my teeth on?   Any help would be greatly appreciated.

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M13 in Hercules should be better placed to observe at night so try to see if you can see that perhaps first. At magnitude 5.8 it should be relatively easy to see and find in a 20mm or so EP, and been higher up too at 50 degrees or so it should reduce the effects of the crud you get looking through the lower parts of the atmosphere. 

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Edited by Knighty2112
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Depending on a number of factors, globulars can be just like fuzzy blobs.  To be sure you're looking at what you think you are, check the starfield around the target against what is shown in Stellarium.  Remember to use CTRL/SHIFT/H to get the inverted view on Stellarium, to match what you see in the eyepiece.

Doug.

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M13 is an excellent choice at this time together with M92 also in Hercules. M15 in Pegasus is also an easy star hop.

When you have located your chosen glob with a low power eye piece try upping the magnification.

Good luck and enjoy.

 

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15 minutes ago, Jordan Konisky said:

Thanks for all your very helpful suggestions.  Is their an eyepiece filter that helps get through the atmospheric crud when looking at stars and clusters that are low in the sky?   For looking at planets can that filter be stacked on to a color filter? 

I'm afraid not Jordan, anyone who invented one of those would be quite wealthy I think!

Don't forget to give M22 a look. It's still relatively low but is a lovely one at mag 5.1

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16 minutes ago, Jordan Konisky said:

Thanks for all your very helpful suggestions.  Is their an eyepiece filter that helps get through the atmospheric crud when looking at stars and clusters that are low in the sky?   For looking at planets can that filter be stacked on to a color filter? 

There are filters that help a little with light pollution (LP), but are kind of hit and miss really. I have one and to be honest really doesn't do too much in my LP polluted garden. Sadly, there are no filters that can help really with the crud lower down towards the horizon. You can however stack filters together, so stacking an LP filter with another coloured filter for planetary viewing can be done. How successful they might be is another matter, as you are also fighting against other seeing conditions and not just LP, so it's a case of try it and see. No guarantee that it will improve any view though. 

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I think it's always going to be limited by looking through a lot of atmosphere. When I've I had a go at Sagittarius clusters from the UK they've always suffered from the effects of looking through a lot of atmosphere, even when seeing is good, compared to the clusters you can see higher up in the sky.

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1 hour ago, Jordan Konisky said:

Knightly 2112, what program did you use to generate the sky map that you included in this thread?  Is in on a PC, IPad or Mac? 

I used Skysafari 5 Pro which I use on both my IPhone 6+ and my IPad Air, however it is also available for Android too. There are three versions available; basic, Plus or Pro version which I have. I got the Pro version as it was on offer at half price, but to be honest the Plus version is OK too unless you want all the bells and whistles that you get with the Pro version. 

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M4's bright magnitude  is deceiving.   It is spread out over a fairly large area,  making it a  low surface brightness object very easy to get washed out due to tghe atmosphere and bad seeing.    I have a 10" dob and view from Virginia and still it's sometimes hard to see.    An easier globular cluster to see in Scorpius is  M80 even though it is 2 magnitudes dimmer.  It's very compact making it appear much brighter than M4.    Another globular cluster to check out is M22 in Sagittarius.   It's not as loose as M4, and it's brighter.   You should be able to resolve it.

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On 02/09/2016 at 15:39, Jordan Konisky said:

walking from Antares, I am able to see, what I think is, the vague, hazy and very dim outline of M4 - not any way near the brightness shown me by Stellarium using the ocular view feature

Your doubt makes me doubt, too; are you sure you have not stumbled upon globular NGC 6144? It's less than 1° north-west of Antares, and M4 is less than 2° west. 6144 is dim and small, M4 is not, but if you stop your star-hop from Antares to the west at the first faint fuzzy you see, there is NGC 6144, the imposter.

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  • 2 weeks later...

Early in the 20th Century your countryman Harlow Shapley made a 3D map of the globulars which showed that they were distibuted around a point in Sagittarius now known as Sagittarius A* - the centre of our Milky Way galaxy. When this point is well placed from your site the globulars are well placed. This is a bit late in the season, therefore, for prime globular hunting but some outliers (further from the galactic centre) are still around.

Olly

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