NGC 3372-Caldwell 92 (core region)

Image with the Homunculus Nebula

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:

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.

Additional Information


Name(s): NGC 3372; Caldwell 92; Eta Carina nebula

Type: Emission Nebula

RA:  10h 45m 04s

Dec: -59ΒΊ 41’ 21”

Constellation: Carina

Size (arcmin): 120×120

Magnitude: +1

Distance: 10,000 ly


Date: Several nights between 2016-02-21 and 2016-03-18

Location:, SSO near Coonabarabran, NSW Australia

Size (arcmin): 37×37

Telescope: Planewave CDK 20” f/6.8

Camera: SBIG STX16803 (4096x4096pix)

Guiding: Astrodon MonsterMOAG off-axis guider

Total exposure: 23 hours (Ha: 7.5h; OIII: 8.5h; SII: 5.5h; RGB: 1.5h)

Processing: CCDStack, Photoshop CC 2016

Leave a comment

Your email address will not be published. Required fields are marked *

error: Content is protected !!