Observing WBL groups in Pegasus

[Martin Meredith]

Continuing the hunt for interesting WBL groups, here are some from last night in Pegasus (which contains no fewer than 44 such groups). All are live stacks of 15s subs, no darks/flats.

WBL 726. The lower left pair is the interacting pair VV2003 (NGC 7771 + NGC 7770), while the face on Sb is NGC 7769. Four fainter galaxies bisect these brighter members in a wavy N-S line. 

 

 

 

WBL 724. This is the central part of galaxy cluster Abell 2666. Main galaxy is NGC 7768, a mag 13.3 elliptical. Field full of delicious edge-ons. Exposure time is actually 10 x 15s = 2m30 (sub exposure length is estimated based on time of arrival differences in Jocular and it sometimes overestimated...).

 

 

WBL 723. Understated group of 5 or more minor galaxies. Lovely member of the Flat Galaxy Catalogue (FGC 2527). The central (though strangely not  the brightest) galaxy is NGC 7740, a mag 15.6 E-S0. Both galaxies at the extremes of the group are brighter, oddly missed in the NGC compilation/observation process.

 

 

 

 

 

WBL 688. A group of 6 NGC galaxies, the brightest of which is NGC 7385, a mag 13.2 elliptical. Distance estimates range from 340-400 MLyrs for group members. Total exposure is 17 x 15s = 4m15.

 

WBL 692. Main group is VV 84 and consists of NGC 7433, 7435, 7736, plus other gxs, interacting at around 350 MLyrs. This is the equal of many Hickson groups and why it didn't make that list I don't know.

 

WBL 685. Tonight's star of the show for me, just the kind of jewel that WBLs sometimes throw up, with the benefit of a field rich in stars. The upper edge on is NGC 7345 and to its right is mag 15.2 type SBa NGC 7342. The group at the base have mags 14.7-15.6. One of the upper edge ones (the one to the right) appears to have a slight curve to it, or perhaps another gx. There are a bunch of fainter and/or more compact galaxies in this field too, unusually for such a star-rich area.

 

 

 

Cheers

Martin

 

 

 

[RobertI]

Great report Martin, those clusters are coming out so well with that setup - I love WBL 692 and 685 - outstanding. I really like the eyepiece view btw, makes it seems more real somehow, hard to explain.

[Martin Meredith]

Thanks Rob. I've adjusted the mount and it seems to have helped to get more useable subs too. I should have added to my report that these were taken with a 60% moon in the same quadrant, so the automatic gradient removal really seems to have helped here. Yes, I favour the eyepiece view not just because it is actually what I am seeing/manipulating on the screen, but because it allows the appropriate level of zoom (and all are rotated with N up which helps me identify objects). Some of these objects occupy quite a small region of what is already a small sensor. 

Martin

[London_David]

I tried following up on these myself last week with a SW150PDS and ASI249Pro colour and ASI290MM mono to see what I could see from my location.

Not as much as Martin is the answer! So I think this post is going to be more interesting on a technical / curiosity front.

However, to change it up I did try in one shot colour. All below are screenshots I've not fiddled with them to bring out more detail - which there definitely is on some nights - unless noted.

Transparency has been very bad here recently, making light pollution worse. I’m going to experiment with some light pollution filters. However, if anyone has any other advice, I’d interested to hear it. One thing I notice is how I very quickly blow out stars to white as soon as I start stacking. That may be because I’m trying to get really dim objects most of the time, I’m not sure.

 

WBL726

Exposure 11m32 (173@4s)

I think this was the most successful of the evening in some ways. No real detail but at least you can start to see some variation in the galaxy, rather than just a smudge. It’s still pretty smudgy though.

WBL 724

Exposure: 9m36 (18@32s)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

WBL 692

Exposure 10m8s (19@32s)

NGC 7433 is in the centre of this frame. Again, no detail.

 

WBL 685

Exposure 10m40 (35@32s)

NGC7345 is in the centre of this image. You can see some of the cluster in the lower left centre.

These are all using the a 1920x1080 sensor crop on the ASI294, the full sensor is much larger, but using it all it makes stacking and stretching slower on the m3 chip on my compute stick. I use the full sensor more on larger objects or if I’m just collecting data to look at later.

I then switched to the ASI290MM mono camera that is more sensitive than the 294Pro. However, while things are easier to see I don’t know if there’s any more depth. Also, since transparency was the issue - there’s still not really any detail. This is the full 1920x1080(ish) ASI290 sensor.

A little more on workflow for those interested.

I usually use the SharpCap brain to set an optimal exposure time for 10m of stacking time. I find that's about optimal for me to start on an object so that I can see a few different things in an evening. What the brain comes back with varies depending on the conditions and I don't always find it works. It often gives a measurement too underexposed so can't find alignment stars to stack with. Some evenings I pick my own numbers based on the analysis of the gain/sensitivity performance of the cameras. Usually this is to reducing exposure times and increase gain to combat bad seeing with short exposures. Also if I want to try and get more detail I’ll use very short exposures. I didn’t do much of that on this run since transparency was the issue not seeing.

I keep the full frame FITS images of the above in stacked and raw frames. and Martin’s excellent Jocular software has changed the way observe. I've just used screengrabs for convenience here.

I will view on SharpCap in the moment as above to acquire data. As I said, usually for about 10 minutes. Occasionally I leave it for longer, sometimes less, sometimes I leave it overnight. I save both stacks and raw frames.

Then, in more sociable hours or on cloudy nights, I take this data into Jocular and take a look to see what else is there. I used to stick data through APP but the AP workflow is time consuming and Jocular is much more fun to use.

I also plate solve and annotate the images for my own notes if I’m interested. I wish there was an easier and better way to do this. I have found no user friendly plate solving / annotation software with the exception of PixInsight which is quite frustrating since it’s so expensive and not actually that user friendly either. The best I've found is uploading to Astronometry and waiting, then copying manually which is less than fun.

Unfortunately, currently the snapshot feature isn’t working on my build of Jocular. So below is another rough Mac screengrab, though this time it is of the FITS data re-stretched in Jocular and inverted.

Again, although there is no detail you can clearly see the two 15th magnitude galaxies NGC7345 (close to centre) and PGC69406 (centre left) and NGC7342 (bottom right) without too much trouble, which I think is pretty good for central London on a bad night thanks to technology.

Edited October 30, 2019 by London_David

[Mike JW]

Hi David, I have just enjoyed reading your post. I will need to read it several times to pick up all your thoughts, experience. It is amazing what you are achieving from such a light polluted site. Your shot of  NGC 7345 is impressive. This is more than I would see using my 20" Dob under mag 5.6/5.7 skies on a good night.

Re Sharp Cap, When I have tried it I have found it way too complicated to achieve anything of worth. I much prefer Starlight Live - so simple, but it limits my choice of camera.

Thanks for posting.

Mike

[London_David]

SharpCap can seem complicated but you can safely ignore most things if you don’t need them. I’ve never used starlight live but I was tempted to buy a lodestar because it had such great reviews.

 

With SharpCap I find I generally only touch a few sliders mainly gain, exposure, plate solve, focus and the histogram. There are extra tools but I often what’sNot helping at the time.  Plate solve makes a huge difference and allows me to just jump directly to objects and they always end up in the center of the screen. 
 

There are some good SharpCap quick start guides - AstroJedi on CN has an excellent one posted. It’s worth playing around with it since you can try it free and add I understand SLL hasn’t been updated in a while. For me I didn’t want software limit hardware performance in choice of camera. 
 

Alternatively, maybe Martin can start a new business as an astro-software developer to fill the gap! I think Jocular is the best electronic observing software at the moment - even in development and problematic as it is now, it’s more fun to use because it’s designed around the things you want to do in EAA rather than ap / hardware control oriented. 

[Mike JW]

Thanks David for your thoughts and encouragement. I tried installing Jocular but failed owing to my lack of understanding computers and how software works.

Plate solving - such poor download speed I cannot download it the software.

Mike