Abell 31 WIP

[KathyNS]

"Abell 31 is a very large, and very low surface brightness planetary nebula in Cancer, about 3 degrees south of the open cluster M 67. The magnitude is quoted as 12.2, but the light is spread out over an area 16.2 arc minutes in diameter."

They are'nt kidding about very low surface brightness! I can barely pick this out from the background noise. Even Ha has to be shot on moonless nights, it is that dim.

After a couple of tries under moonlight ("Hey, it's Ha, it'll be fine..." ), I tossed a lot of data and started over on some recent moonless nights. Unfortunately, this target is already past the meridian at sunset, so I only get a few hours per night on it. I figure another three or four nights will give me enough data for a decent image. But that may have to wait until next season. It is worth pursuing, because it is BIG, much bigger than run-of-the-mill planetary nebulae.

So, this is Abell 31.

Orion 200mm f/4 Newtonian
Atik 383L+

19x 600s Ha, 1x1
14x 900s O3, 1x1

Total exposure time so far: 6h40m.

[Peppy]

Very nice, well done.

[BABOafrica]

Never even heard of this one before.

Excellent capture. I especially love the color.

BTW, you said "big". You mean like Trifid Nebula .... That kind of size ???

BABO

[MariusD69]

Wonderful! Well done!

[KathyNS]

BTW, you said "big". You mean like Trifid Nebula .... That kind of size ???

It is 16.2 arc-minutes across, so more than half the size of the full Moon.

[metastable]

How’d the stars end up white? Did you superimpose the narrowband over rgb?

[Gordon]

Congratulations Kathy on having your image selected as todays TSS APOD!

app.php/article/4-16-2021-tss-astrophot ... of-the-day

[messier 111]

superb , love the details , thx

[Juno16]

Pretty cool Kathy!

Amazing that you can pull off an image like this from such a dim target. Great capture and congratulations!

[helicon]

Great image Kathy and the colors are wonderful. Congrats on winning the APOD for today.

[Makuser]

Hi Kathy. A superb Abell 31 image. Although it is somewhat faint, you did a great job on capturing the bi color nebulosity and details. Thanks for taking the time to put this work up on here for us to enjoy Kathy, and congratulations on winning the TSS APOD Award today.

[j.gardavsky]

Hello Kathy,

and thank you for this amazing bicolor astrophoto with a very nice color rendition.

It brings back my memories how difficult has been this nebula visually through the 15x85 binoculars, due to its uneven distribution of light.
The star hopping is to the parallelogram of the faint stars, well visible on the astrophoto.

Clear skies,
JG

[KathyNS]

How’d the stars end up white? Did you superimpose the narrowband over rgb?

I extracted the stars from both the Ha and Oiii images using Starnet++. I did my colour processing on the starless nebula images, then I re-inserted the stars from the Ha image, which were cleaner than those from the Oiii image. When I get this to a final image, probably next season, I will shoot some RGB to get realistic star colours.

[Ruud]

Ooh! That's beautiful!

[KathyNS]

Hello Kathy,

and thank you for this amazing bicolor astrophoto with a very nice color rendition.

It brings back my memories how difficult has been this nebula visually through the 15x85 binoculars, due to its uneven distribution of light.
The star hopping is to the parallelogram of the faint stars, well visible on the astrophoto.

Clear skies,
JG

Wow! You saw it in binos??! That is amazing! Those must be some seriously dark skies you were viewing under!

I was astounded at how dim this object was. It is barely above the noise threshhold in my subs.

[STEVE333]

That's really pretty Kathy. Well done on a tough target. Look forward to next year's version.

Steve

[TheButcher]

Excellent Image Kathy and Congrats on the APOD!

[ic_1101]

Nice capture Kathy, congratulations on the TSS APOD!

[j.gardavsky]

Hello Kathy,

and thank you for this amazing bicolor astrophoto with a very nice color rendition.

It brings back my memories how difficult has been this nebula visually through the 15x85 binoculars, due to its uneven distribution of light.
The star hopping is to the parallelogram of the faint stars, well visible on the astrophoto.

Clear skies,
JG

Wow! You saw it in binos??! That is amazing! Those must be some seriously dark skies you were viewing under!

I was astounded at how dim this object was. It is barely above the noise threshhold in my subs.

Hello Kathy,

and first of all, congratulations on the APOD!

From my observing notes: Binoculars 15x85, filters blue(RGB)CCD: very faint disc, slightly irregular, averted to direct vision, 27th February, 2019,
and on the 30th March 2019 confirmed through my 6" F/5 achro.

As Scott on CN is collectingg the observing reports of the Abell planetaries through the smallest apertures, these 85mm binoculars may be the smallest ones.

Technically,
I have got very good and often unexpected views with the blue(RGB)CCD filters, but the sensitivity of my dark adapted vision has moved with age towards the shorter wavelengths.

Thank you for your kind words,
JG

[kt4hx]

Very nice indeed Kathy, and congrats on the APOD.

I re-observed the so-called Medusa Nebula over a year ago at our dark site with the 17.5 inch. There seems to be variations in its listed visual magnitude and angular size. Using the data I have for it, the visual magnitude is 11.3 and its size is 10.0'. That works out to a mean surface brightness of around 16.04. So yeah, quite dim. Well done.