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B33 (horsehead) and NGC2024 (flame) in Ha


ottUp
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This image of IC434, Barnard 33 (the Horse Head Nebula), and NGC2024 (the Flame Nebula) is the start of a project. This monochrome image was taken in Hydrogen Alpha during a nearly full moon.

This is 1.5 hours of H-Alpha exposure (6 x 10 minute + 2 x 15 minute), calibrated with darks, flats, and bias frames. SXV-H9 camera with Astronomik H-Alpha filter, on SV80S refractor, on pier-mounted Losmandy G11 mount, guided by SXV guider on a Pronto.

Considering I could read by the moonlight, and that it was minus 18 degrees, I'm quite pleased with this result. More light and more colours to be added as skies permit.

- Richard

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Edited by ottUp
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Very cold!! Where are you?

The image as presented is a little overexposed but I doubt that the original data is really burned out. Could you not get more out of it by dropping the high part of the curves? I'd be inclined to have another go at stretching the image open, maybe not lifting the curve so high at the top?

Olly

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The image as presented is a little overexposed but I doubt that the original data is really burned out. . . . I'd be inclined to have another go at stretching the image open, maybe not lifting the curve so high at the top?

Olly

Hi Olly.

Thanks for the feedback. I'm just starting this black art and stretching, histogram management, etc., is still pretty much a mystery, so I welcome any advice.

I tried adjusting the upper threshold a bit to allow more top-end brightness in and you're right - it seems to allow more detail through in the bright clouds. Is this the kind of thing you meant?

- Richard

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Hi Richard,

That's a bit better, although you are still over exposed on the flame neb. Here is something I do to control bright detail that may work for you:

Use curves to roll off the top end, then pull the level down in the histogram. This compresses the top end rather than cutting it off, and hopefully there should still be detail in there while still being bright.

The flame is quite hard to control in a pic like this as it's so much brighter than the clouds behind the horsehead, and the tempation is to concentrate on the clouds

Thanks

Euan

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Thanks for the pointers, Euan. There is so much to learn in this field. I haven't taken the time yet to learn how to use Curves, and your advice tells me it's time to do that. A next attempt:

- Richard

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Edited by ottUp
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