Bubble Nebula NGC 7635 and M52

This view to the north of Cassiopeia spans about 3 times the apparent size of the full moon. It frames the Bubble Nebula to the lower right and the open Salt-and-Pepper star cluster to the top left. The Bubble Nebula’s shape comes from the interaction of the stellar wind off the bright star within, SAO 20575 (BD+60°2522), with the giant surrounding molecular cloud.

The relative distances and sizes in this photograph are quite interesting. The M52 cluster is roughly twice as close to us at the Bubble Nebula (about 4600 light-years vs 8500), and it is also roughly twice the size (about 25 light-years vs 10). I think this makes for a nicely balanced composition.


  • 106× 150-s light frames (Gain 900) from 133 overall (best 80%)
  • 4 h 25 min total exposure time
  • Full use of calibration frames (darks, flats, dark flats and bias)


  • Explore Scientific ED 102 mm Apo f/7 refractor
  • Revelation Adjustable Field Flattener
  • Sky-Watcher EQ6-R PRO SynScan GOTO equatorial mount
  • Altair Hypercam 294C PRO colour fan-cooled camera
  • Altair quad-band one-shot colour (OSC) 2″ filter
  • Pegasus FocusCube v2
  • Altair 60mm guide scope
  • Altair GPCAM2 AR0130 mono guide camera
  • Hystou Rugged Fanless Mini PC i5 7260U


  • SharpCap 4.0
  • PHD2
  • DeepSkyStacker
  • Photoshop

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