The Rosette Nebula, NGC 2237,  is an amazing large HII region located in the Monoceros constellation. We call this object a “star nursery” because new stars are being born in it.

The nebula lays some 5.000 light years away from us and measures 130 light years in diameter spanning over 5 times the angular diameter of a full moon.

In the core of the Rosette Nebula can we find the open cluster NGC 2244 that sculpts, with its strong winds and radiation, the entire nebula creating this characteristic and aesthetic shape.  

This starless image, with a total exposure of 13.5 hours, is the result of combining narrow band data, with the use of [SII], Hα, [OIII] filters, and broad band data, with the use of Red, Green and Blue filters. The blue colors correspond to the oxygen emissions, while the reddish regions correspond to the hydrogen and sulfur emissions.

Image Details

Hα: 32×600″

[SII]: 9×600″

[OIII]: 18×600″

R: 18×300″ – G: 12×300″ – B: 18×300″


Calibration: 50 darks, 50 bias


All images taken at 0Gain Bin1 -25ºC


Total exposure:  13,5h

Data acquisition 2018


FSQ85ED telescope

Mesu200 mount

ASI1600MM Pro camera with ZWO EFW 8 pos

Guiding with ASI174MC and ZWO OAG

Baader filters



Aleix Roig – Prades, Tarragona (Catalonia, Spain), May 2021.

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