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Martin Meredith

Some EAA observations in LEO

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Last night was one of those marginal nights with thin cloud moving across the FOV, easily visible on most subs. Nevertheless, EAA still works surprisingly well in such conditions!

Here are a few objects from a short session in Leo. I'm continuing to seek out members of the WBL catalogue of 'weak galaxy groups', but I often pan across to a bright galaxy to check alignment, and this time I happened on one I don't recall seeing before. And what a beauty! How Messier missed this I'll never know. BTW I had it down as NGC 2905 but it is NGC 2903 I believe; NGC 2905 is apparently a bright star cloud within the galaxy (maybe that fuzzy thing south of the bright arm below the core?).

 

1627396483_NGC290511Mar19_20_18_53.jpg.cef2914bd344d1b04baac2028754578b.jpg

 

So, to the WBLs. The great thing about this catalogue is that it is hard to find any information about them, so it is always a surprise to see what kind of configuration of galaxies awaits. Here's a close-up of WBL 324 along with a chart showing the members. Amazing to think that nearly everything in this image is galactic. This group is also known as Shakhbazian 352. It is not often that Shakhbazians have NGC galaxies amongst their members. This is a pretty bright example.

 

1858809782_ScreenShot2019-03-12at18_35_04.thumb.png.2a514fc136911247bcf2c01578227539.png

 

I then headed to WBL 353 which claims something like 72 members. This is just the Eastern part:

10630740_WBL35311Mar19_20_56_23.jpg.a97257eb476b9162087732ff06e4c066.jpg

In fact, this is part of the very rich Abell-Corwin-Olowin galaxy cluster Abell 1367. Here is most of the rest of it:

555051905_anon11Mar19_21_27_00.jpg.4bac55bddc261e96f5e0069f5a00b38c.jpg

 

I rarely feel the need for a larger sensor -- surely 0.4 Mega pixels is enough for anyone ? -- but this one would have benefitted with a wider FOV.

I find myself observing for quite long periods (this one is no exception) and make no apologies for producing such a long duration stack. In this case the clouds were visible on nearly every sub but even so, with time, it was possible to see at least 2 of the 3 quasars, indicated in the chart in this close-up of part of the Abell cluster:

 

1997309606_ScreenShot2019-03-12at19_05_43.thumb.png.860282a2aaf41c93678de042d684caab.png

 

The ones visible had mags 18.5 and 19.1. The one I can't make out is mag 20.2. But it just shows that even marginal sessions can be very rewarding.

Thanks for looking

Martin

 

 

 

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Martin 

Excellent shots. 

Have you got room for a focal reducer if you want more FOV? Possibly not worth it for occasional use and a bit of a performance putting it in refocussing etc. 

Bill 

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Lovely session Martin. Fascinating to see those quasars and using your deep maps is a great way to explore the scene. The inverted view, although not quite so pleasing to the eye, is perfect for revealing detail. Some of the stars are much brighter on the image than the map, I guess they are variables. Jocular working really well. ?

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Posted (edited)
On 12 March 2019 at 18:13, Martin Meredith said:

I rarely feel the need for a larger sensor -- surely 0.4 Mega pixels is enough for anyone ? -- but this one would have benefitted with a wider FOV.

 

Great images.  I always like to consider FOV in units of 'width in light years' at the distance of the main objects imaged. 

What would that be in these cases?

Edited by AKB

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Thanks Bill. I think I would need smaller pixels to make good use of a focal reducer. I did try one some years ago to more or less fit Markarian's Chain on to my Lodestar C. I'm not averse to looking for a wider FOV at some point although I still feel I could spend the next 5 years happily observing e.g. all the Arps with my current sensor.

Actually, I was interested to know just how many individual galaxies won't fit on the Lodestar and it turns out to be 3, one of which is M33 (which more or less fits), another being in Tucana so little hope of seeing it from these latitudes. Only 25 out of nearly 10000 non-Abell galaxy groups that I have access to in my database don't fit, and around 31of the Abell galaxy clusters.

Thanks AKB. I'm not sure what the actual width in light years would be in this case. But you've given me an idea for the future, which is to compute it and display it as one zooms in on a known cluster or object. Or perhaps colour-code by depth. Its sometimes hard to visualise the layers of distance that we are looking at in virtually any image.

Cheers Rob. I don't think they're necessarily variables -- just bad mapping! I spend ages trying to find the most appropriate mapping of star sizes on the charts. Its hard to get something that works well given the kind of stretches we habitually use but I could almost certainly make some improvements to the middle range (mag 14-17). To be honest, I'm not sure what the next steps with the charts will be. I had intended to update them with the GAIA data, but the PDF format may not be the best given that so many PDF readers are hostile to the use of internal links it seems. Certainly updates are on the back burner for the moment while I continue to develop Jocular. Hopefully the two will be marriable one day.

Martin

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Excellent work, Martin!

It’s amazing to see what the Lodestar can produce, and your Jocular program is quite remarkable.

Don

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