NGC 4395

[tomato]

Is it just me or are small targets being posted less frequently these days compared to the deep wider field images?  At one time, a lot of imagers aspired to a large aperture RC but now F2 RASAs and the like seem to be more in the spotlight.  Anyway, here is another small and somewhat obscure galaxy image, it is Galaxy Season now, after all!

This is NGC 4395 in Canes Venatici, a low surface brightness galaxy some 14 million light years away from our own Milky Way.  The brighter active regions have their own NGC numbers, 4399, 4400 and 4401 but these were not picked up by PI's annotation script for some reason. Captured with the Esprit150/ASI178 rig as follows: 

Lum 166 x 2 mins

Red 83 x 2 mins

Green 85  x 2 mins

Blue 68  x 2 mins (Blue the poor relation once again) Total integration 13.4 hrs

Calibrated and stacked in APP, LRGB combination in APP, processed in PI with the (for me) obligatory RC suite of AI tools. I deliberately eased off on NoiseXterminator to try and emphasise the structural detail, such as it is. Now is that 'swastika' structure in the spiral arm at 4 o'clock real or an artefact? I've seen something similar on other images but I suspect BXT has joined the dots, but hey, it can only work with what it is given.

Thanks for looking.

 

[ONIKKINEN]

Never heard of this one, added to my ever growing list of things to image 👍.

Interesting looking galaxy, all kinds of messed up and a lot of different types of signal to be captured in spiral arms, H2 regions etc. I think the aversion to small and faint targets is  somewhat easily explained by the typical weather a typical imager posting here on SGL experiences which greatly demotivates most of them from dumping dozens of hours on a target that may or may not be worth it in the end.

[Moonshed]

All I know about the new RASA f2 scopes is that a lot of amazing images have been posted, and I do mean amazing! I’m aware that I am somewhat jealous of the images they produce, I can’t compete with my ancient 8” f10 ( improved to f5 with EasyGuider) Celestron but nonetheless I am proud of the very average images I have managed to produce with it.
I can’t help thinking though that using a RASA makes it so easy that less skill is needed by the operator, maybe I’m wrong in which case I’ve no doubt I shall soon be corrected 😊.

This is probably just me ‘cos I can’t afford one myself 😩

 

Edited February 27, 2023 by Moonshed

[Radec]

Wow, what an excellent image - never imaged it nor seen anyone else do it, so well done on a great first.

 

[tomato]

1 hour ago, Moonshed said:

All I know about the new RASA f2 scopes is that a lot of amazing images have been posted, and I do mean amazing! I’m aware that I am somewhat jealous of the images they produce, I can’t compete with my ancient 8” f5 Celestron but nonetheless I am proud of the very average images I have managed to produce with it.
I can’t help thinking though that using a RASA makes it so easy that less skill is needed by the operator, maybe I’m wrong in which case I’ve no doubt I shall soon be corrected 😊.

This is probably just me ‘cos I can’t afford one myself 😩

 

Having experience of imaging with a RASA8/OSC IMX571 combination, I would say that once you have the camera aligned, imaging with it is reasonably straightforward. It holds focus well, doesn’t need a high cost mount with precise guiding, the corrector plate doesn’t dew up with a camera blowing warm air across it, and deep images can be completed in a single session, so I guess it is no surprise that they are now a popular choice in that budget range.

But… they aren’t really meant for small targets, of which there are literally hundreds to go at. The trouble is imaging them is always going to be a challenge from the UK given our weather and poor seeing, but how does the quote go, “We choose to do these things…”

[wimvb]

Great capture. Re the "swastika", I think it's an artifact from deconvolution. Whenever I get this kind of ridges, I back off on the amount of deconvolution I apply. In the "classic" decon routine in PI, I would increase the Global Dark and Global Bright settings. In BXT, I would reduce the strength or play around with the psf settings. Here's a reference image with good resolution.

https://www.astrobin.com/lmdzt0/B/?q=Ngc 4395&camera=

Btw, have you considered adding Ha? Will be a real boost.

https://www.astrobin.com/full/gvdyz4/C/

Edited February 28, 2023 by wimvb

[tomato]

Thanks @wimvb, I will look at the BXT settings, all I did was use a manual PSF value from the image, everything else was set at default.

Thanks also for the image link, I was using an image taken with a 400 mm reflector, although there is some filamentary structure, it doesn’t make the distinctive pattern present in my image.

Ha is a great idea, especially as the moon is now butting in, big style.

[DaveS]

Oh no, yet another galaxy to image lol

As for small targets I'm starting out on my quest to image as many of the HCGs as I can. I won't get all of them, but we'll see how many I end up with. I've already got my Trius 694 on the ODK 12 for a totally bonkers 0.46"/px.

Regarding RASAs, given that you really want about 1000 mm FL with today's small pixel cameras, that implies a clear aperture of 500 mm. Anyone want to hazard a guess at how many figures in the price?

[CCD Imager]

It is a refreshing change to see a smaller higher resolution object and you have captured it well. Maybe you should offer a challenge to imagers on SGL - planetary nebula!! Watch em struggle with those

Adrian