Globular clusters in NGC 253

[Xilman]

NGC 253 is q starburst spiral galaxy in Sculptor. It is 11.4 million light years away and so is well outside the Local Group. There are at least 82 confirmed globular clusters in orbit around it and a number of candidates which await confirmation. They range in brightness from 18.4 to 23.1 so the brighter members are well within range of imaging by amateurs.

This image was 1560 seconds with a unfiltered SX 814 camera on a 0.4m Dilworth. The contrast has been stretched to show the fainter globulars and so the galaxy itself is over-exposed.

Some GCs lie outside the field, some are lost in the galaxy, and some are too faint to be visible in this image. I intend covering more of the field and going deeper with longer exposures but that will have to wait.

Six confirmed globular clusters (out of a total of 82) are marked. I didn't check for candidate clusters. From the top, they are numbered 148, 146, 139, 109, 168 and 99 in table 3 of A VST and VISTA study of globular clusters in NGC253. by  Cantiello et al., Astron. Astrophys. 611, A21 (2018). Their g magnitudes are given as 20.98, 21.00, 20.53, 21.12, 20.32 and 20.43 respectively.

Others are encouraged to try for extragalactic globular clusters. Those in the local group are within range of a 20cm scope. The Sculptor and the M81 groups of galaxies certainly with a 30cm. The brightest in NGC 253 is magnitude 18.43 and I've seen an image of M31 taken through a 8cm refractor which reaches that magnitude ...

 

 

 

[Paul M]

Another great result Paul, but I won't be trying my luck on this one. As I type, this object is culminating at an alt of 11 deg. Not that I can see it through the cloud layer...

To think that these specks, a few pixels, are huge masses of uncountable stars... 

[Xilman]

4 hours ago, Paul M said:

Another great result Paul, but I won't be trying my luck on this one. As I type, this object is culminating at an alt of 11 deg. Not that I can see it through the cloud layer...

To think that these specks, a few pixels, are huge masses of uncountable stars... 

La Palma does have the advantage of being 20-odd degrees further south than the UK. That said, I know that some people around here use remote telescopes at southern latitudes.

Anyway, the M81 clusters are at a comparable distance, so comparably bright, and M81 is circumpolar from the UK. Well within your capabilities, in other words.

[wimvb]

GC hunt? Here's what I managed some time ago

https://stargazerslounge.com/topic/404408-ngc-185-a-dwarf-galaxy-and-its-globular-clusters/

https://stargazerslounge.com/topic/402885-ngc-147-with-globular-clusters/

 

[wimvb]

13 hours ago, Xilman said:

well outside the Local Group

Too far south for me, I’m afraid. I may try to capture some further North. Any suggestions?

[Xilman]

3 minutes ago, wimvb said:

Too far south for me, I’m afraid. I may try to capture some further North. Any suggestions?

See https://britastro.org/observations/observation.php?id=20190311_020000_9a2c47fcf9f3ee97

and

https://britastro.org/observations/observation.php?id=20190311_020000_14c9b7973142fb48

[Xilman]

Globular clusters much further afield are accessible to amateurs.

HVGC-1 (https://en.wikipedia.org/wiki/HVGC-1) is 54M light years away in the Virgo cluster. My image is below.

M87 has many thousands of known GCs - hundreds, if not dozens, are visible in long-ish exposures.

 

Edited October 18, 2023 by Xilman
Fix link

[tomato]

Yes, some of the massive GCs associated with M87 are relatively easy to capture, I collected a few when attempting to image the plasma jet.

[Xilman]

7 hours ago, wimvb said:

Too far south for me, I’m afraid. I may try to capture some further North. Any suggestions?

Just took a look at your M81/82 image on your website. I am pretty sure that if you re-processed to enhance stellar details rather than dust and nebulosity you will find quite a few GCs in it. 100 hours is far longer than anything I have ever taken.

[wimvb]

3 hours ago, Xilman said:

100 hours is far longer than anything I have ever taken.

That was an image that I only processed. The data came from the IKI observatory:

 

[ONIKKINEN]

Whats the best tool to use in finding these distant globulars from images? Interested in going on the hunt myself, but at least the toolset in my use doesn't have obvious globular annotation capabilities.

[wimvb]

1 hour ago, ONIKKINEN said:

Whats the best tool to use in finding these distant globulars from images? Interested in going on the hunt myself, but at least the toolset in my use doesn't have obvious globular annotation capabilities.

Either Vizier from the university in Strasbourg, or a script called TypeCat in Pixinsight

You can access Vizier from the Simbad database/front end or from aladin. All from Strasbourg

https://simbad.cds.unistra.fr/simbad/sim-id?Ident=M 87

TypeCat uses Vizier and creates catalogues that can be used directly in PixInsight's image annotation script

https://www.skypixels.at/HVB_Repository/

Edited October 18, 2023 by wimvb

[Paul M]

I've had success using a feature in ASTAP that annotates Simbad objects within your specified search area.

Here I just selected an object in an old, low quality JPEG of M33 I captured a while ago that looks Globular Clusterish and chose Simbad Annotation.

It is a Glob and then selecting Online querie gave me all the usual Simbad info.

 

https://simbad.u-strasbg.fr/simbad/sim-coo?Radius.unit=arcsec&Radius=10.079011&Coord=23.5297324401d%2B30.5341685257d&OutputMode=LIST&output.format=HTML

[ONIKKINEN]

1 hour ago, wimvb said:

Either Vizier from the university in Strasbourg, or a script called TypeCat in Pixinsight

You can access Vizier from the Simbad database/front end or from aladin. All from Strasbourg

https://simbad.cds.unistra.fr/simbad/sim-id?Ident=M 87

TypeCat uses Vizier and creates catalogues that can be used directly in PixInsight's image annotation script

https://www.skypixels.at/HVB_Repository/

Thank you, TypeCat is just the tool i wanted for the job. PixInsight threw me trough an update loop of course but all sorted now.

Now i see that these things are everywhere, never would have guessed there are so many that can be found.

[wimvb]

Not the galaxy of this thread, but I used TypeCat in PixInsight to make a list  of the globular clusters of M81. I then used that in the Image annotation script.

[Dan_Paris]

Very interesting topic Paul, thanks for your post. I wish there was a simple way to include extragalactic globulars databases in Pix or ASTAP annotation tools...

[wimvb]

On 17/10/2023 at 19:46, Xilman said:

Others are encouraged to try for extragalactic globular clusters.

THE hidden galaxy (not IC 342) ... with a bonus https://stargazerslounge.com/topic/416757-the-hidden-galaxy-not-ic-342-with-a-bonus/

[tomato]

Thanks Wim, for high lighting  the Type Cat script for Pixinsight, of which I was totally unaware. I went for an easy target first M33, but I will look at my more obscure galaxy images and see if I can find some GCs there.

[maw lod qan]

Amazing!

I know  very well that I will never see many of the unbelievable sights above me, with my own eyes and equipment. 

But through the images and knowledge you share, I get to view it.

Thanks!