Author Topic: Horsehead nebula from Bromley 2nd try  (Read 420 times)

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Carole

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Horsehead nebula from Bromley 2nd try
« on: Dec 30, 2017, 11:22:47 »
Further to my other thread, I have reprocessed the RGB data removing as much gradient as I could and I think I have made a better job of it this time.  Still unable to use the Luminance. 

Same info as before:
Ha 21 x 900secs + 10 x 600secs - Almost 7 hours
RGB 32 x 150 binned total 1hour 20mins
Grand total 8 1/4 hours
SW130PDS & Atik460EX, HEQ5

« Last Edit: Jan 01, 2018, 17:26:28 by Carole »

The Thing

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Re: Horsehead nebula from Bromley 2nd try
« Reply #1 on: Dec 30, 2017, 13:35:11 »
This is looking good Carole. It's never going to look as smooth as a monochrome frame with the RGB added, you've got some nice Ha detail and it's interesting to compare the dust below the Horsehead to my slightly over MMT transformed version.

Carole

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Re: Horsehead nebula from Bromley 2nd try
« Reply #2 on: Dec 30, 2017, 13:42:34 »
Thanks Duncan, I guess I am never going to get the detail you have managed from my location.  Trouble is getting to a dark site in the winter is not really easy.

Carole

Carole

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Re: Horsehead nebula from Bromley 2nd try
« Reply #3 on: Dec 30, 2017, 17:26:33 »
I forgot to mention. 

The target went behind next door's tree and I was waiting for the guiding or imaging to go weird before I stopped it (as I was indoors doing it remotely).  Was very surprised to find that with one exception, the guiding managed to keep going as did the images.  The branches are quite thin, so I guess the 900sec exposures evened themselves out, but I was surprised that the guiding didn't throw a hissy fit.

So that was interesting.

Carole

JohnP

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Re: Horsehead nebula from Bromley 2nd try
« Reply #4 on: Jan 01, 2018, 11:50:21 »
Blimey that is amazing from Bromley Carole - well done & shows just what can still be done despite the light pollution - John

The Thing

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Re: Horsehead nebula from Bromley 2nd try
« Reply #5 on: Jan 01, 2018, 13:03:23 »
Just a thought Carole, you've got lots of detail in the emission nebulae but a lot less in the reflection nebulae. This must be because you have a lot of Ha data compared to RGB, maybe you could up the percentage of RGB and spend a little less time on the Ha? As I only shoot RGB I have found lots and lots of shorter subs have improved my images no end - 300s vs. 120s, half the subs in my latest stack were done with light pollution and only a UV-IR filter and these are mixed with subs taken after 'lights out' at 23:00 CET (I'm very lucky on that front!) but because of the number of subs it doesn't seem to matter too much.

Carole

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Re: Horsehead nebula from Bromley 2nd try
« Reply #6 on: Jan 01, 2018, 14:36:39 »
Thanks very much John.

Quote
Just a thought Carole, you've got lots of detail in the emission nebulae but a lot less in the reflection nebulae. This must be because you have a lot of Ha data compared to RGB, maybe you could up the percentage of RGB and spend a little less time on the Ha? As I only shoot RGB I have found lots and lots of shorter subs have improved my images no end - 300s vs. 120s, half the subs in my latest stack were done with light pollution and only a UV-IR filter and these are mixed with subs taken after 'lights out' at 23:00 CET (I'm very lucky on that front!) but because of the number of subs it doesn't seem to matter too much.

The reason I didn't take so much RGB Duncan is because I tried it while the Moon was up, and the data was quite awful, so had to wait until the Moon had disappeared and then I only had a short window before the HH disappeared behind the trees.  On the 2nd night, I didn't have that window as with the Moon coming up that much later that cut it down to even less, but then clouds came in anyway. 

I must confess, that I have a LP filter, but because I do so little RGB from Bromley, I keep forgetting to put it on.  So this was done entirely without a LP filter, which of course doesn't matter for the Ha.

Lastly, I would have got more detail on the emission nebula if I could have used Luminance as well, but I started to take it but it was quite awful. 

If I get a chance I will try to get Luminance and some more RGB using a LP filter, though how effective it will be with LED lighting I am not sure, but there is probably still a lot of sodium lighting around as some nights I look at the sky with averted vision, and the whole sky looks red.

Thanks for the thoughts though, gives me something to think about.

Carole


The Thing

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Re: Horsehead nebula from Bromley 2nd try
« Reply #7 on: Jan 02, 2018, 10:37:52 »
Ah yes Carole, but plenty of awful data can add up to a decent image in the end. Hence why I now try to take 100+ short subs rather than 30 long ones.

Carole

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Re: Horsehead nebula from Bromley 2nd try
« Reply #8 on: Jan 02, 2018, 12:04:06 »
I'll post up the rubbish Luminance to give you some idea of what I am talking about. 

I am taking shorter RGB these days, I find 150secs binned works quite well.

BRB

Carole

Carole

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Re: Horsehead nebula from Bromley 2nd try
« Reply #9 on: Jan 02, 2018, 12:27:03 »
This is 3 x 600secs Luminance.  After examining the subs I decided to give up capturing any more.


MarkS

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Re: Horsehead nebula from Bromley 2nd try
« Reply #10 on: Jan 02, 2018, 22:50:14 »
Which night did you take them?

If the moon was out then there's no surprise you have gradients.

Mark

Carole

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Re: Horsehead nebula from Bromley 2nd try
« Reply #11 on: Jan 02, 2018, 22:56:52 »
I waited until after the Moon had set Mark to take the RGB and Luminance.

Carole