Pelican Nebula in narrowband

[timc]

Attached is a narrowband image of the Pelican Nebula IC5070 in the constellation of Cygnus.  The nebula lies approximately 1,500 light years from us and is part of an enormous cloud of hydrogen gas which lies in this region and which is being illuminated by nearby stars.  This nebula is very popular with astro-imagers as it is large and relatively bright. The Ha channel is particularly strong and makes for wonderful monochrome images.  I’ve imaged this target previously, but this time I thought I would experiment a bit and remove the stars to focus the eye on the textures in the clouds of gas and the various shades of blues and yellows produced by using the Hubble narrowband palette.

 

I used a remote robotic telescope in Siding Spring Observatory, Australia, operated by itelescope.net on 18th 19th and 20th June 2018 to capture the data for the image.  The image consists of the following exposures: Ha 300s x 11, OIII 600s x 12 and SII 600s x12 all binned x2, giving a total of 4 hours and 55 minutes imaging time. The telescope I used was a Planewave 431mm (17 inch) Corrected Dall-Kirkham astrograph at f/4.5 mounted on a Planewave Ascension 200HR mount with a FLI Proline 6303E CCD camera.  I processed the downloaded calibrated sub-exposures in CCD Stack2 with further processing in Photoshop CS5 using the Hubble palette (ie Ha channel mapped to green, SII to Red and OIII to blue). Thanks for looking.

 

Tim C

[Brian Mills]

Hi Tim,

I can't fault the quality of the image (or of the equipment used to take it) nor your processing skills but for me (personally) the loss of the stars means the image loses a lot of it's context.

It could easily be many other things other than a nebulous object in the depths of space.

Cheers

Brian

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[JR]

Hi Tim

That is amazing.  I particularly like the right hand side of the nebula which really does look like it's being illuminated by some huge celestial light bulb.  It's good to see the structure unimpeded.  The images of the associated N American nebula often seem to suffer from star overload.   

What would be nice is an interactive facility to fade the stars in and out to taste, using some sort of layer arrangement and a viewer accessible transparent slider.

James

Sent from my iPad

On 28 Mar 2021, at 12:07, timc <tcos...@gmail.com> wrote:



Attached is a narrowband image of the Pelican Nebula IC5070 in the constellation of Cygnus.  The nebula lies approximately 1,500 light years from us and is part of an enormous cloud of hydrogen gas which lies in this region and which is being illuminated by nearby stars.  This nebula is very popular with astro-imagers as it is large and relatively bright. The Ha channel is particularly strong and makes for wonderful monochrome images.  I’ve imaged this target previously, but this time I thought I would experiment a bit and remove the stars to focus the eye on the textures in the clouds of gas and the various shades of blues and yellows produced by using the Hubble narrowband palette.

 

I used a remote robotic telescope in Siding Spring Observatory, Australia, operated by itelescope.net on 18th 19th and 20th June 2018 to capture the data for the image.  The image consists of the following exposures: Ha 300s x 11, OIII 600s x 12 and SII 600s x12 all binned x2, giving a total of 4 hours and 55 minutes imaging time. The telescope I used was a Planewave 431mm (17 inch) Corrected Dall-Kirkham astrograph at f/4.5 mounted on a Planewave Ascension 200HR mount with a FLI Proline 6303E CCD camera.  I processed the downloaded calibrated sub-exposures in CCD Stack2 with further processing in Photoshop CS5 using the Hubble palette (ie Ha channel mapped to green, SII to Red and OIII to blue). Thanks for looking.

 

Tim C

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[tcos...@gmail.com]

Thanks for your kind comments gents, they are much appreciated.

@Brian,  generally speaking I agree with you regarding removal of stars from astro-images. I have seen this done on images of other targets and sometimes felt that it works but other times not, for the very reasons you state (ie placing the object out of context, total dissociation from space and the universe). However, given this nebula is so well known I thought it would be interesting to try the technique for the first time and I am pleased with the end result. Reduction of the sizes and numbers of stars is a common step in narrowband image processing as, depending on the target and the star field it is sitting in, the stars can sometimes overwhelm the nebulosity which is the subject of these images.  Very large stars are also sometimes reduced in broadband images for the same reason. Of course, this is all subjective and a matter of personal preference.

@James, I like your idea of an image where the viewer could vary the amount of stars. I think some special web-page functionality would be required which is quite beyond me! However, I was going to produce a ‘with stars’ version of this image in any event, so I will get on and do that, hopefully over Easter.  Forgive me, but I could not resist the temptation to post this ‘without stars’ version as soon as it was finished!

Best wishes

Tim

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[Trev S]

Tim, Wow!  That is in a completely different league.  I guess a combination of dark skies, large aperture and skillful processing are involved?  Trying to determine which part of the pelican it is, is that the head/beak area?

[JR]

Beyond me too Tim.  It seems a common enough thing using 'hover mouse' over web images to see before and afters, or enlargements.  There must be an app for that by now!

James

James

Sent from my iPad

On 28 Mar 2021, at 20:18, tcos...@gmail.com wrote:



<image001.jpg>

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[tcos...@gmail.com]

Hi Trev thanks for your kind comments. All the factors you mention (dark skies, telescope aperture and processing skills) all play a part, although I would say that it is possible to get nice images of this nebula from the UK as it is strong in Ha and also OIII. See attached a Ha monochrome image I took from Oxted back in 2017 with a 4 inch refractor. Hopefully you can get a better sense of which bits of the pelican are what from the Ha image! The round dark spot is the eye with the bill pointing down to the left and the head extending up and to the right. I always think it looks a bit like the flying dinosaur Pteranodon, but we each see different things in these images!

Best wishes

Tim C

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