November 21, 2024

NGC 7635 – The Bubble Nebula in Cassiopeia

NGC 7635 – The Bubble Nebula in Cassiopeia

Telescope: Astro-Tech 8” f/8 Ritchey-Chretien, Orion Atlas EQ-G

Camera: QHY 367c Pro, 0C, Baader Mk III MPCC

Filter: GSO IR Blocking Filter

Guide scope: Astro-Tech 60mm, ZWO ASI120MM mini, PHD2

Exposure: 33x300sec, gain 2800, offset 50, saved as FITS, dithered every 2 images

Darks: 32, 0C, gain 2800, offset 50, saved as FITS

Flats: 64x500ms, Tee shirt flats taken at dusk

Average Light Pollution: Red zone, Bortle 8, fair transparency

Lensed Sky Quality Meter: 18.6

Stacking: Average, 1 sigma clip

White Balance: Nebulosity Automatic

Software: SharpCap Pro, Deep Sky Stacker, Nebulosity, Photoshop

This is NGC 7635 is almost the inverse of a planetary nebula. Planetaries are expanding shells of gas shed from a dying star. The Bubble is formed from the intense radiation a hot blue star pushing out a spherical void in the surrounding gas and setting the hydrogen aglow with a beautiful red color. The Bubble looks like a delicate Christmas ornament on an unimaginable scale.

NGC 7635 rises in the northeast in the early evening and is high overhead at dawn.