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Martin Meredith

Four WBL galaxy groups

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The 732-member  WBL catalogue of galaxy groupings tend to have relatively sparsely-distributed members and differ in this sense from the more compact groups such as the Hicksons (although some Hicksons are also members of the WBL catalogue, I think). Armed with nothing more than RA/Dec, I often like to dip in to the WBLs just to see what is there, as these are under-appreciated objects and don't appear on (m)any charts. The results can be quite varied, but typically consist of 3-7 galaxies that fit on my small sensor. Here are 4 from last night.

WBL 676 is very close to the bright star o AQR and consists of 5 main galaxies, though a sixth mag 18.6 galaxy is also visible as a fuzzy blob just N of a star. The lowest galaxy is NGC 7182. I'd say this is a fairly typical (not particularly exciting) WBL object type, with the galaxies strung out across the field. Seeing was quite good through most of the session but seems to have deteriorated for this object. Nearby is Shakhbazian 81, a very challenging compact group of about 11 faint galaxies.

 

1810067254_WBL67604Oct19_09_13_47.png.0ecb8ab9b8e6c5fcccc869d40d6037c7.png

 

Also in Aquarius is WBL 669, a 3-member group. Again, nothing particularly spectacular.

 

376964543_WBL66903Oct19_21_45_51.png.7aa7d8b04ee84160ffc39fd54e8abd11.png

 

Aquila contains just one WBL group, again a triplet. I enjoy looking for WBLs in star-rich constellations as the combination of a dense star field with galaxies in the distance is appealing and unusual. The 3 galaxies form a near equilateral triangle with the base composed of mag 14.2 Sc type UGC 11524 and mag 14.7 SBc UGC 11522 which are at a distance of around 250 M Lyrs and may well be interacting. 

764848409_WBL66203Oct19_21_09_26.png.fb4a81688f8998b84fa79bc9cac2b69c.png

 

Finally, back to Aquarius for WBL 666, one of the six WBLs in that constellation. This is a real beauty, with 7 individually-interesting galaxies in the field, and it is finding configurations like this that motivates me to explore the WBLs. I reckon this would make a good AP target.

Interestingly, these galaxies are all at a similar distance of 180-200 M Lyrs so may be a physical grouping. On the inverted shot I've marked the 5 NGC galaxies and a couple of quasars. Q1 is mag 19.5 with a redshift of 2.06 (8-9 billion LYs?), while Q2 is mag 19.6 but much closer, with a redshift of 0.18 (around 2 billion).

The non-inverted shot is an LRGB as I decided to add a little colour (although it is mainly luminosity so the effect is subtle).

2140079635_WBL66603Oct19_22_03_56.png.7f159ee4fbd1d83f7f1f857106291781.png

 

169451596_WBL66604Oct19_09_35_54.png.096408f24ff3600943ade73dbad62279.png

 

Thanks for looking

Martin

 

 

 

 

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Thanks for these. An interesting set of images, Martin. Good demonstration of how inversion and addition of colour draw attention to different aspects of the field.

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On 04/10/2019 at 08:55, Martin Meredith said:

I decided to add a little colour

Jocular does colour??  When did I miss that.

Tony

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HI Tony

It isn't fully finished yet but will be in the next release. It supports LRGB from mono rather than OSC. I'm still working on a few aspects as it has meant a fairly complete redesign of the way I handle the stacks as you might imagine. L, R, G and B subs can be added in any order, as they come in, and Jocular will update the relevant stacks so colour balance will always be consistent even if the noise in any one of the bands is higher than the others. Internally all is done in LAB space which means getting the live aspect working responsively has been a challenge. Its ~ 200ms per update when using colour on my 2015 MacBook Air for the small Lodestar chip which is just about OK. For instance, any changes to the luminosity channel that come from e.g. moving the B or W points also take this amount of time due to the need to go through LAB space. Beforehand those changes took ~30ms so it is quite a hit, although if the incoming subs are all L then it is as fast as before.

The idea is to really simplify the handling of colour. At present there are just 3 controls: saturation, colour stretch and colour binning. No messing around with  histograms!

One further integration I'd like to do before release is with Nebulosity, so that hitting a single control on Jocular results in a scripted capture of LRGB i.e. one-shot LRGB. At present I'm using SLL to control the filter wheel and captures and it works by simply naming the channels red, green, blue which Jocular then interprets as expected. 

Narrowband will come later still....

Here's a recent example.

Best

Martin

 

 

 

1472532237_Hickson9208Oct19_18_35_25.png.16c5870281139214543d3b71f25113ef.png

 

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On 27/10/2019 at 07:24, Martin Meredith said:

The idea is to really simplify the handling of colour. At present there are just 3 controls: saturation, colour stretch and colour binning. No messing around with  histograms!

+1 for that!

On 27/10/2019 at 07:24, Martin Meredith said:

One further integration I'd like to do before release is with Nebulosity, so that hitting a single control on Jocular results in a scripted capture of LRGB i.e. one-shot LRGB. At present I'm using SLL to control the filter wheel and captures and it works by simply naming the channels red, green, blue which Jocular then interprets as expected. 

 

Would that also mean that we could script an OSC capture / debayer / split into separate RGB, so that Jocular would see it as a mono capture with different filters?

Tony

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