TheSkySearchers

M33 is relatively close at about 2.73 million light years distant. The three 'majors' in the Local Group are M31 (Andromeda), M33 (Triangulum), and the Milky Way. M33 is the smallest of the three at a diameter of about 61,000 light years; Milky Way - about 87,000 light years; and Andromeda - about 152,000 light years.

M33 is a well studied galaxy and has many prominent emission structures with multiple survey catalogs of these structures. I focused on four catalogs (BCLMP, CPSDP, [LHK2017], and [RVP2013]) for the annotated image. I grouped them (circled) into similar parts of M33 and listed the contained emission items. There are also emission structures of M33 in the NGC and IC catalogs.

There are also several background galaxies and Quasars in this image that can be seen in the full size and annotated images.

Click the image below - it links to the main page with image and additional information. There is also a link below to the full FOV and annotated image. The full resolution image has a horizontal FOV of 1.38 degrees and an image scale of about 0.73 "/pixel.

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  M33 with Emission Structures

Full FOV image (Pan and Zoom):
M33 with Emission Structures(Sh2-221)

Annotated Image (Pan and Zoom):
M33 with Emission Structures Annotated

Images also available on astrobin -M33 with Emission Structures

Scope: FSQ-106N at f/5
Camera: ASI2600MM (Astronomik type 2c Ha OIII, LRGB, filters)
Location: DAA Observatory, Shelter Valley, CA

Breathtaking image, full size is a keeper!

But, I can't sit still for the 20 hours to get this,
Steve

Great Image Jim,

The Ha looks awesome in this shot...

Looks amazing! Great work, Jim!!

Yes, the HA in this image is very well done. Great image!

Fantastic image Jim.

I'm curious about your observatory. I went to your website and saw the build photos. Are you imaging remotely now or do you have to go to this location to do your imaging?

Amazing image of M33! Nicely done!

Congratulations Jim on having your image selected as our TSS APOD!

app.php/article/4-18-2024-tss-astrophot ... of-the-day

sdbodin wrote: ↑Wed Apr 17, 2024 1:20 am Breathtaking image, full size is a keeper!

But, I can't sit still for the 20 hours to get this,
Steve

Thanks for your comment Steve! I have to say (with a guilty look) that I slept for a good deal of the capture. That's nice, but I find I am trading off time watching the camera capture with planning the composition andsequence during daylight hours. I still enjoy being out under the stars. I am on location for all my exposures - just some of the time I am sleeping.

StarHugger wrote: ↑Wed Apr 17, 2024 8:14 am Great Image Jim,

The Ha looks awesome in this shot...

Thanks for your comment! Much appreciated.

MariusD69 wrote: ↑Wed Apr 17, 2024 3:01 pm Looks amazing! Great work, Jim!!

Thanks for your comment Marius!

this is probably the nicest version of m33 i have seen, thx.

Amazing Jim, simply amazing!

Congrats, Jim. Really special image. How did you go about blending in the HA. It turned out so natural and is really seamless.

--Steve

Congrats on the TSS APOD. That really is a beauty!

Thanks for your comments and congrats folks! I appreciate them.

starfield wrote: ↑Fri Apr 19, 2024 4:19 pm Congrats, Jim. Really special image. How did you go about blending in the HA. It turned out so natural and is really seamless.

--Steve

Thanks Steve!
So I did data acquisition on Ha and O3. With the two NB stacks reasonably normalized, I did a pretty standardized HOO color map on the starless Ha / O3 stretched stacks. I black clipped the starless NB color mapping and then just did a straight screen blend into the LRGB broad band final image. I actually think that you had described a similar technique that you picked up from Adam Block. Anyway, I kinda did what I thought you were describing and got this result. Also, I had some comments on astrobin that suggested that maybe the O3 data combined with the Ha produced this natural look - I don't know, maybe. I did the O3 acquisition because I knew (and had seen) that there was quite a bit of O3 content in the M33 emission structures.

I put the starless NB color image on astrobin (Rev D) - this was the 'natural' image before black clipping. You can look it up there and blink between the broad band image and NB starless image to see the difference with NB added.

https://www.astrobin.com/6dcr6b/D/

very nice, worth the click for full screen version, good details in the surrounding nebula

jthommes wrote: ↑Fri Apr 19, 2024 11:31 pm Thanks for your comments and congrats folks! I appreciate them.

starfield wrote: ↑Fri Apr 19, 2024 4:19 pm Congrats, Jim. Really special image. How did you go about blending in the HA. It turned out so natural and is really seamless.

--Steve

Thanks Steve!
So I did data acquisition on Ha and O3. With the two NB stacks reasonably normalized, I did a pretty standardized HOO color map on the starless Ha / O3 stretched stacks. I black clipped the starless NB color mapping and then just did a straight screen blend into the LRGB broad band final image. I actually think that you had described a similar technique that you picked up from Adam Block. Anyway, I kinda did what I thought you were describing and got this result. Also, I had some comments on astrobin that suggested that maybe the O3 data combined with the Ha produced this natural look - I don't know, maybe. I did the O3 acquisition because I knew (and had seen) that there was quite a bit of O3 content in the M33 emission structures.

I put the starless NB color image on astrobin (Rev D) - this was the 'natural' image before black clipping. You can look it up there and blink between the broad band image and NB starless image to see the difference with NB added.

https://www.astrobin.com/6dcr6b/D/

I think you nailed what makes this look so good - bet it's the O3. Looking at your NB starless it doesn't look like it doesn't impart the same red cast that you'd get with just HA. Maybe I'll give this a try with M101. --Steve

Very impressive work, Jim!

best,
Bernhard

Congratulations Jim on the well deserved APOD!