NGC 3372-Caldwell 92 (core region)

NGC 3372 is also known as the Eta Carina nebula, an object that is already described here. This image is a much closer view, taken with the 20 inch telescope. This image was taken in narrowband, except the stars, that were imaged in RGB. The surprising novelty in this image is the filter-color pairing. The filters have been assigned colors so as to better mimic the “natural” spectrum of this nebula. The red color has been obtained by blending (at different proportions) Hydrogen alpha (bright red) and Sulphur II (this one is a natural dark red). Green has been obtained with only Oxygen III. Blue has been obtained by blending OIII and a small proportion of Halpha, in order to account for Hydrogen beta, well into the blue part of the spectrum and responsible for the pinkish-magenta appearance of the pure Hydrogen emission regions. In this image, pure red colored regions mean that they appear in the SII images, but not in the Halpha or OIII. The use of narrowband filters (and the telescope/camera) account for the extreme amount and quality of the details that can be seen in this image. The Homunculus Nebula (just around Eta Carina, the bright star off to the left of center) is not visible in detail, but a small elongated blob marks its presence.

This image has been selected as AAPOD (Amateur Astronomy Picture of the Day) on July 17, 2016: http://www.aapodx2.com/2016/20160717.html

Recently, I started a project to get an image of the Homunculus Nebula. The result is shown in the image at center and its blending with the complete image is shown on the right. The Homunculus has been taken only in Narrowband (all RGB attempts were unsuccessful) and mapped to natural color. Exposure times ranged from 0.1 sec to 1 second.

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