Astro-Images | Doing Cartwheels

Like many people these days, I have a lot of spare time. One project I enjoy is taking three grey-scale images from the Hubble Telescope archive and combining them to produce color versions. The Hubble Legacy Archive (HLA) collects the vast array of images from the telescope into a searchable site available to the public. Knowing the name of the object or keywords, one can search for images made by a variety of instruments and filters.

The oval object below is an unusual galaxy called the Cartwheel. It was imaged with a grey-scale sensor as the light passed through a green wavelength filter. Imaging was also done with red and blue wavelength filters not show here. But, they look similar.

Hubble Legacy Archive

Desktop computer software lets me open the red, green, and blue images simultaneously and combine them into a color RGB version. The balance of colors is adjustable for the look I want.

Hubble Legacy Archive | My version

Hubble Legacy Archive | My version

This Hubble grey-scale filtered image is NGC 4826 of a distant galaxy with dark dust clouds around it. NGC stands for New General Catalogue. The NGC includes many types of deep space objects, including galaxies, star clusters, emission nebulae and absorption nebulae.

NGC 4826 | Hubble Legacy Archive

NGC 4826 | Hubble Legacy Archive | My version

Lastly, NGC 5307 is a nebula of expanding gas around a star that has collapsed near the end of its lifetime.

NGC 5307 | Hubble Legacy Archive

NGC 5307 | Hubble Legacy Archive | My version

There are enough images in the HLA to keep me occupied for the rest of my life. I hope this virus isolation doesn’t cause me to exhaust that library.

3 thoughts on “Astro-Images | Doing Cartwheels

  1. I’ve seen instances, on Flickr and Twitter, of people doing just what you are doing and – as you imply – it seems to be very addictive, especially as all the Hubble images are such high quality.

    I’m going to stick with my own much more modest colour camera for now but maybe down the track I’ll give it a go.

    Some people are critical of the way astronomical images are manipulated, not using “true colours”. Very often two images of the same object can look quite different. The concept is to use colours to bring out the details, which you have done very well. The concept of true colours is irrelevant anyway as astro-imaging cover the full spectrum from radio waves and infrared to UV, X-ray and gamma rays, where “colour” is arbitrary.

    I look forward to seeing more like this from you.

    Regards from Oz 🙃

    • Thank you for your comments. I agree with you about the use of color. It has limited use in showing the true way something would look to the eye. We ‘see’ such a small part of the spectrum.

      I will post a few more over time. There is a heading on my blog called Astro Images showing past attempts.

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