Good morning. It’s November 10, and today’s image reveals a faint supernova.
It has the official name CTB-1, and after its discovery in the 1950s, it was thought to be a planetary nebula. (Regular readers will remember that planetary nebulae turn out to have nothing to do with planets.) CTB, in case you’re wondering, stands for “Cal Tech Observatory Catalog B.”
The object has since been identified as a supernova remnant about 10,000 years old and known colloquially as the “Garlic Nebula.” The reason should be fairly obvious. It also happens to be a difficult astronomical object to photograph, which is why I think Ken Bates’ presentation today is so great.
“It’s a very faint object, and without narrowband filters, it’s almost impossible to image,” Bates told me. Narrow band filters capture specific wavelengths of light. “Narrow gamut images often result in purple stars, and since I don’t really care what that looks like, I took additional exposures of about 2.5 hours at wide range using RGB filters. I removed the stars from the gamut image Narrowband then extracted the starlight from the RGB image, calibrated the colors using data from the GAIA satellite database, and then combined the color-calibrated stars into the narrowband image to give this result.
The image itself consists of approximately 51.5 hours of total exposure time taken over a two-week period in late September and early October. Bates shot the Garlic Nebula from his home in the Black Forest north of Colorado Springs.
Source: Ken Bates.
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