NGC7635 – The Bubble Nebula Wide-field

NGC7635 – The Bubble Nebula Wide-field

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Revisiting the Bubble Nebula from last year, the area surrounding the Bubble is rich with nebulosity and cluster M52, making it a fine wide-field target.  In this case, I decided to shoot narrowband — typically, narrowband star colors are purple or off-color depending on the palette used, and for this particular image, I decided to mix in natural color RGB stars to make the M52 cluster look more natural.

The Bubble Nebula, NGC7635 and Sh2-162, is an emission nebula in Cassiopeia about 10,000 light years away.  The bubble itself (about 10 light years across) is formed and pushed out by a massive star in the middle of the bubble — its stellar wind irradiating the gas and causing it to glow.  M52, the nearby open cluster, is roughly 5,000 light years away.

Bubble Nebula and M52 (Annotated)
Bubble Nebula and M52 (Annotated)


The narrowband images consist of 24 1200s Ha, 16 1200s OIII, and 16 1200s SII with a Tak FSQ106 and QSI683 camera.

For RGB stars, I took 8 180s exposures each of R, G, and B.  The short exposures are sufficient as stars saturate quickly, but typically, longer exposures are needed to bring out the faint nebulosity (not needed in this case).  While the RGB stars image was intended only for star color, the image below is what the area looks like in natural light.  Despite the short exposure, the Bubble itself is reasonably bright!

NGC7635 - The Bubble Nebula (short RGB exposures for star color)
NGC7635 – The Bubble Nebula (short RGB exposures for star color)


Resolution ........ 2.103 arcsec/pix
Rotation .......... -84.787 deg
Focal ............. 529.66 mm
Pixel size ........ 5.40 um
Field of view ..... 1d 55' 39.6" x 1d 26' 27.9"
Image center ...... RA: 23 21 15.462  Dec: +61 10 53.65