NGC 3293 in HaRGB

[Placidus]

Greatly inspired by Mike Sidonio's version, thrilled to notice that our brand new replacement generator (with remote start/stop) had just arrived from Melbourne, but aware of the full moon, we thought we'd do something very bright to celebrate.

Hydrogen alpha 1x1 hour (mapped to red), and RGB 15x60 sec each. Each pixel is the brighter of the H-alpha and the RGB images.

Original image here (https://photos.smugmug.com/Category/Clusters/i-fB5v8q8/0/5372328d/O/Gem%20Cluster%20Ha%201hr%20RGB%2015 %20min%20each.jpg)

There is a great deal of fine wispy detail in the H-alpha. We are guessing that the very orange star in the cluster is a red giant nearing the end of its days.

In the RGB-only image, we noticed some very faint blue reflection nebulosity which is not visible in the combined image. We have pushed the attached RGB-only thumb to bring it out. In previous work, an OIII filter shows it is reflection nebulosity rather than OIII, which is extremely sparse in this field.

Edit: We've just noticed the reflection nebulosity is quite clear in Mike Sidonio's (www.iceinspace.com.au/forum/showthread.php?t=166476) HaRGB image, so we just need more hours and a more thoughtful way of combining the Ha with the RGB.

Further edit: Here we've increased the blue channel, but using the luminance as a mask, so the reflection nebulosity is brighter, but the H-alpha and the stars are unchanged.

Best,
Mike and Trish

[RickS]

Very pretty, M&T. With some more data perhaps it would be possible to show the Ha and reflection nebula together? That would be cool...

Cheers,
Rick.

[gregbradley]

Very nice Mike. the ha version turned out a bit better.

I have an image of the same area but widefield. It definitely does have wispy Ha filaments around the Pendant.

Greg.

[Placidus]

Thanks, Rick. This would have to be our shortest image ever, and yes, we'd love to get the Ha and the reflection nebula simultaneously.

The story of the generator dying: During the 4 months (120 beautiful nights) that the camera was off being repaired, we didn't use the system. Mud wasps got into the generator house, and glued up the housing fans. We started the mighty Honda EU30iS generator, about the only beast in the 1-3 KVA range that has a 20 hour run time on a single tank. We were
concentrating on the camera instead of our usual safety checks and didn't notice that the fans were performing feebly. The generator hummed away inside a closed box, sooting everything including its air filter, making it run richer and richer, smokier and smokier, hotter and hotter ... until it sooted up its own innards like a 1952 Ford Prefect running on two stroke. It probably also cooked some of its control electronics. Luckily it didn't catch fire.

We had seriously modified the generator ignition and start circuits so that we could stop it remotely under computer control. I was therefore too embarrassed to take it to the doctors to say, please save the patient, she is very ill and it's all my fault.

The Generator Shop in Melbourne now sells an EU30iS with a remote start-stop kit, with both wireless (100 meters) and two-wire interfaces. The two-wire interface is just about plug compatible with our old system for stopping under computer control (yippee!) and semi-kosher so no more having to service it in shame and privacy ourselves. (The remote start is for the far future. We will need big batteries, and some sort of wireless link from the house which is 350 meters away and only just line of sight. It's not relevant for now). We also fitted a ducted exhaust vent, so no more fans, and wire mesh, no more mud wasps practicing architecture in secret and without permission.

So you can see we were busting to try things out.

Best,
MnT

[Placidus]

Thanks, Greg.

We've searched high and low for your image (search terms: gregbradley plus one of gem, cluster, carina, 3293), but you do so much superb stuff that we can't find it. Can you give us a link?

Andy Campbell also did a fine widefield shot showing much H-alpha detail.

[gregbradley]

I set my Yamaha 3.7kva with a 22 hour tank time on fire by accident "servicing it". A great generator but its a writeoff. I got a smaller Yamaha 3kva and 20 hour tank time but no electric start.

With the cost of petrol up and solar down a solar system to run your observatory would make long term economic sense at some point. A petrol generator costs around $30 a night to run plus oil changes etc.

Greg.

[PKay]

Inspirational image MnT :thumbsup:

For me a real benchmark, something to aspire too...

And maybe keep a fire extinguisher handy!

[Geoff45]

Great picture there M&T. I actually prefer the RGB with its colour variation. Using max(Ha,R) does seem a bit heavy-handed. Perhaps just blend in a smaller percentage of the Ha.

[Placidus]

Scary story! Fuel-wise, the Honda has an "Eco" mode, where it sits at idle most of the time and only uses about 10 litres a night. Its biggest disadvantage for us is its lovely red super-compact cabinet, which makes it hard to get at the gizzards, and its elaborate silencing system which makes it a heroic job to fit an exhaust duct to suit a lift-off enclosure.



Thanks, P, glad you like it. We have 20,000 litres of water set aside for fire fighting, and a mobile pump with a 400 litre tank, but neither's much good for petrol of course, so we try to keep the area around the unattended midnight beast flame-proof. It really is something to think about. As Greg says, in the future, solar will be the way to go.

[Placidus]

Thanks, Geoff. You are right of course. This is our very first attempt at combining Ha and RGB, and all hints are welcome. It was 1:30 am when we processed the image, and we weren't thinking straight.

It's off to the Orange Show (a kind of harvest festival). We'll practice being subtle when we get back.

Again, any hints on how to combine Ha with RGB (concentrating on the maths, not someone's impenetrable proprietary script) is most welcome.

Best,
MnT

[RickS]

You may find Ha-(R-med(R))*F helpful, where F can be calculated from the bandwidth of the two filters but usually ends up being tweaked until it looks right :) Somewhere between 0.1 and 0.2 usually works for my data.

This is a poor man's continuum filter...

Cheers,
Rick.

[Placidus]

Thanks, Rick. I'll digest that over a glass or two tonght. Meanwhile, here is a version where I've enhanced the blue channel of the RGB, but using the luminosity as a mask, so the star colours remain untouched.

[RickS]

Wow! Lovely rich colours, M&T.

[Atmos]

For such a small amount of data this really shows how many photons get sucked up with 20" of aperture!

One thing I have learned from PixInsight is that what you select as the normalisation frame makes a difference.
When I use LinearFit I usually use Ha as the reference as it is the cleanest and has the most exposure time. This leads to very red dominant (Ha dominant) images where any of the Hb signal or reflection nebula is lost.

If I LinearFit all the frames to the Red channel however it helps preserve the correct colour balance while adding the Ha signal to the dimmest red areas.
I believe that fitting everything to Ha gives a better SNR but at the cost of colour balance.

I do a Max(Ha,R) function for creating the red channel. It adds Ha to the dim areas while keeping the bigger fatter R stars.

[Geoff45]

Looking good Mike

[atalas]

Nice work on a wonderful cluster guys!

[strongmanmike]

He he this looks familiar..."The test shot in Moonlight cluster" :lol:

Yeah the blue is there for sure and I think shooting RGB (at least) under a dark New Moon, is the best way to tackle showing this properly, not to mention the other colours in the region...and plenty of exposure of course :) I found it difficult to show the blue well too and it was due to these two factors for sure.

Mike

[Placidus]

Cheers, Rick. A technique new for us.



Thanks, Colin. That's helpful advice.





Thanks Geoff and Louie.



Hi, Mike! Yes, "Test shot by moonlight" can only be a taste test, but now we're hooked. Next new moon there will be a fight over whether to do this or the Sombrero.

Best,
MnT

[SimmoW]

Lovely cluster and ha detail Team, you should try and combine 1 and 2.

Wow that generator story sounds bad, and thanks for the tip off 're the mud wasps. Though once I left my mount out for a few weeks, and yes they started nesting on the mount! I dreaded looking looking into the scope!!

[Placidus]

Thanks muchly Simon.

Your mud wasp story reminds us of Greg Priestley's story of the Huntsman Nebula. There was a huntsman on the lens of his Canon.

[John K]

Great image and a beautiful field.

Clear skies and hope the new generator delivers!

John K.

[Andy01]

Nice work guys - :D THIS THREAD (http://www.iceinspace.com.au/forum/showthread.php?t=138473) is Gold for blending Ha & LRGB.

Hope that's useful ;)

[Placidus]

Thanks John!



Cheers, Andy! I read through Marco's methods, and it made complete sense.

Best,
Mike

[multiweb]

Missed that one. Another great shot Mike. :thumbsup:

[Placidus]

Thanks, Marc, that's kind.