Date: 4 August 2022

Altitude: 52 - 56 degrees

Angular Size: 1° 00' x 0° 45'

Position Angle: 1° 04' from north through east

Orientation: North up; East left

Pixel scale: 1.30" per pixel

Total exposure time: 61 minutes

B filter: 32 x 47 seconds

V filter: 32 x 37 seconds

R filter: 32 x 31 seconds

Caldwell 9 is also known as Sharpless 155 and the ”Cave nebula”

Emission nebula

Constellation: Cepheus

Diamater: 35 light years

Distance: 2,400 light years

Notes

Sh2-155 lies at the edge of the Cepheus B cloud (part of the Cepheus molecular cloud), and is

ionized by young stars from the Cep OB3 association. It has been suggested that radiation

from the hot O-type star HD 217086 is compressing the region, triggering the formation of a

new generation of stars.