TheSkySearchers

Last night was our first clear moonless night in a while so a few buddies and I took advantage of the conditions and headed to a location in the Mojave National Preserve that is about 25 miles outside of Baker, CA.
Conditions were excellent and my SQM-L meter gave an overhead reading of 21.35. I'm not sure what that converts to on the Bortle scale but we all seemed to agree that it was a strong Bortle 2 sky. To the northeast, over 70 miles away, we could still see the lights of Las Vegas, NV, and the same with Barstow, CA, 70 miles to the west of our location.
I started out capturing 15 minutes of 60second subs for each of the LRGB channels and then proceeded to capture 200 minutes of Ha data with 5-minute subs. Finally, I started the OIII channel and managed to capture 65 minutes worth of 5-minute subs before my target reach 20°above the horizon and I called it quits for the morning around 1:30 am. That nearly 2-hour drive home is a killer after a long day of projects around the house followed by a long evening of imaging.
I'm hoping to get some more dark time in and add another hour or two of OIII data and see if there's any SII data in this target as well.

Explore Scientific ED127mm refractor with .7x reducer/corrector = 652mm f5.25
ASI ZWO1600mm camera - Gain 139: Offset 10: cooling to -10°
CGX Mount
NINA capture software handled everything like a champ, framing, guiding, auto-focusing, Meridian flip
Processed in Astro Pixel Processor and PhotoShopCC.

I am not a good post-processor and have little desire or tolerance to learn PixInsight. Processing took me 15 minutes. I'm planning on giving the individual masters for the channels to my buddy that is a PixInsight guru and let him have a go at the data to see what he comes up with. I'll post his results, which I'm absolutely positive will be much better than mine, later on in this same post. I'm still not happy with the green stars...

Nice tight stars and lots of color. Pretty version of this target.

Steve

magnificent picture.

thx.

One word: Sweet!

All the best,

Excellent image Greg. The stars look very nice and I particularly like the delicate pink fringing of the nebular structure.

Regarding your comment about your SQM-L reading as it relates to the Bortle scale, there is no relationship between them actually. The Bortle scale was developed by John as an in the moment method to assess one's conditions using the naked eye only over 20 years ago. It is a fluid scale that can vary night to night at a location, or even hour to hour. The SQM meters of course measure sky brightness. The Bortle scale, SQM and colored LP maps are all based on differing criteria and methodology. They are all valuable tools, but not directly interchangeable, though they do compliment one another. I know John does not like people attempting to correlate his scale to either the maps or SQM - gets his dander up a bit!

kt4hx wrote: ↑Sun Feb 07, 2021 3:21 am Excellent image Greg. The stars look very nice and I particularly like the delicate pink fringing of the nebular structure.

Regarding your comment about your SQM-L reading as it relates to the Bortle scale, there is no relationship between them actually. The Bortle scale was developed by John as an in the moment method to assess one's conditions using the naked eye only over 20 years ago. It is a fluid scale that can vary night to night at a location, or even hour to hour. The SQM meters of course measure sky brightness. The Bortle scale, SQM and colored LP maps are all based on differing criteria and methodology. They are all valuable tools, but not directly interchangeable, though they do compliment one another. I know John does not like people attempting to correlate his scale to either the maps or SQM - gets his dander up a bit!

Thanks for the compliment on the photo and thanks for the info regarding the SQM-L reading. Good to know and no dander riling was meant.

That's beautiful

Looks great! Well done!

AstroBee wrote: ↑Sun Feb 07, 2021 3:58 am

kt4hx wrote: ↑Sun Feb 07, 2021 3:21 am Excellent image Greg. The stars look very nice and I particularly like the delicate pink fringing of the nebular structure.

Regarding your comment about your SQM-L reading as it relates to the Bortle scale, there is no relationship between them actually. The Bortle scale was developed by John as an in the moment method to assess one's conditions using the naked eye only over 20 years ago. It is a fluid scale that can vary night to night at a location, or even hour to hour. The SQM meters of course measure sky brightness. The Bortle scale, SQM and colored LP maps are all based on differing criteria and methodology. They are all valuable tools, but not directly interchangeable, though they do compliment one another. I know John does not like people attempting to correlate his scale to either the maps or SQM - gets his dander up a bit!

Thanks for the compliment on the photo and thanks for the info regarding the SQM-L reading. Good to know and no dander riling was meant.

You are quite welcome Greg.

Regarding Bortle, no problems at all. There is a lot of erroneous info out on the internet about how the Bortle scale tracks with other methodologies then is repeated through no fault of the speaker. Different individuals have attempted to forge some correlation between Bortle and SQM/maps which is then proliferated through the internet. Whenever I see it, I just try to illuminate the fact that they cannot be consistently and accurately correlated one to another. Rather they are complimentary. When John's scale first appeared in the February 2001 edition of Sky & Telescope and we didn't have the SQM or colored LP maps around yet. They all assess things differently.

Just FYI, in a conversation that John was participating in at another site, someone made the following statement:

I live in a 5, with level 4 beginning about 10 minuets away, and level 3 a bout an hour and a half or so.

To which John replied:

Point of information, don't delude yourself. No one can claim that they live in one Bortle class zone of sky darkness, but have the next darker (or brighter class) region only a few minutes away. The odds are that in making that ten minute drive you will actually find that the skies there will be little to absolutely no different than at home. The sharp demarcations between class zones depicted on light pollution maps are at best a generalization. There actually will always be broad transition zones that separate where the relative darkness increases ever so slowly from the one zone to the next. At the same time , prevailing conditions at just about any site are changing from night to night, so there can be no absolute guarantee that the assumed class conditions will prevail upon arrival at a site, unless it is a pristine night to begin with.

Yeah, LOTS of color in there. And it's hard to get all that detail. DARK sites trump all the rest.

BABO

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

app.php/article/2-7-2021-tss-astrophoto ... of-the-day

Hi Greg. A wonderful Thor's Helmet image from you. I enjoyed the bi-color nebulosities and fine details in your capture. Thanks for posting this on here Greg, and congratulations on winning the TSS APOD Award today.

Congratulations on the APOD.

Hi Greg

Lovely image.

I agree with Alan's comments about Bortle /SQM although I too have been guilty of saying that Bortle 1 is a mile down the road. I don't want to hijack your thread or steal your thunder with so I'll just say congratulations on the TSS APOD.

Cheers

Joe

Wow, thanks again for the APOD recognition. I always appreciate it.
I'm eager to see my friend's version of the same data processed with PixInsight and way more skills than I have.
My goals are to try and master, if that's even possible, the data acquisition part of this hobby with the gear I have. Then eventually work on improving my data processing skills. I keep waiting for that next version of PixInsight to come out that does everything to perfection with 3 clicks of the mouse...

@OzEclipse I always encourage conversation, even if it changes the topic direction. Just since my initial post, I've done lots of reading and research myself on the whole Bortle/SQM topic so I'm always learning.

Nice image of Thor's Helmet Greg. Reminds me that I watched "The Dig" last night on Netflix since the skies were not cooperative. It's the story of the Sutton Hoo excavation back in 1939 in the south of England where a 6th century (probably) Anglo-Saxon ship was recovered along with a majestic helmet, surely belonging to a king, powerful chief, or warleader along with some other grave goods. The ship very much approximated Viking ship design, just a couple of hundred years earlier.

AstroBee wrote: ↑Sun Feb 07, 2021 10:00 pm Wow, thanks again for the APOD recognition. I always appreciate it.

@OzEclipse I always encourage conversation, even if it changes the topic direction. Just since my initial post, I've done lots of reading and research myself on the whole Bortle/SQM topic so I'm always learning.

It is an interesting topic but perhaps a topic for its own dedicated thread in a different sub-forum. I may start one.

Joe

Same data, re-processed to work on the star colors. I felt like v1 had too many green stars in it. I'm always looking for improvement.

Beautiful, the star colors look great too.

My friend Patrick finally had a go at my data on Thor's Helmet. I gave him the master calibrated files from each color channel, LRGB, Ha, OII, and here's his explanation of what he did with it in PixInsight and PS.

"I used a tone mapping approach - short version, MureDenoise on all channels, extracted the stars from HA/Oiii/R/G/B (didn't use the Lum), combined the RGB stars for the colors. Combined the starless H and O, re-linearized then heavily denoised and stretched for the chrominance. Combined the starless H and O to create a synthetic superluminance, re-linearized, usual masking, deconvolution, stretching, etc. Added the Ha stars back in, recombined with chrominance image. Extracted the a* and b* channels from RGB stars and recombined them with the main image through a mask created from the Ha stars. More tweaks, final color tweaking in Photoshop.
Used Starnet to create the starless images. Did some tweaking of the stretch and resulting images to reduce the Starnet artifacts."

Be sure to give Patrick some love and follow him on Astrobin. Check out his wide-field of Orion! https://www.astrobin.com/users/FlankerOneTwo/



I love the way the stars seem so much more realistic in size and brightness.