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NGC2237 “Rosette” in Monoceros
 We have already seen the NGC 2237 “Rosette” nebula imaged by Martin Myslivec in real colors. Well, almost real colors, as this image was acquired through two narrow-band filers, passing only very small portions of the visible spectrum (deep-red Hα line and blue-green OIII line). But because the nebula shines mainly in these two colors, its appearance is close to how humanís eye could see it. Now Martin added another exposure, taken in near infra-red SII line, which is even redder that Hα line and human eye cannot see it. So, it is not possible present such images in real colors and so-called “false colors” are used instead.

There are many ways how to assign visible and invisible colors captured by CCD camera to red, green and blue colors visible to humans. On such combination is called “HST palette”, because images captured by Hubble Space Telescope (HST) made such images popular.

Once we get used to the fact, that the image is colored to be aesthetically pleasant despite completely differently than is its real appearance, we can further play with colors. The image above in fact does not follow the HST palette, but uses its variant called “gold”. Just to illustrate how the original HST palette looks, Martin provided also image strictly adhering to this standard.

Martin used his G3-16200 camera on 30†cm, f/3.8 Newtonian astrograph telescope. Total exposure time achieved 31 hours. We encourage everyone to click on respective images to explore them in details. True quality of astronomical photographs is hidden is details and is revealed when we examine them in high resolution. Perfectly focused, round stars and rich details in nebulosity make these images state-of-the-arts.

To save our readersí time, we also provide the real-color-like bicolor image of the NGC 2237 “Rosette” nebula here despite we already presented it in separate article on our web site.

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