• NGC 7331 and Stephan's Quintet in Pegasus
    • NGC 7331 and Stephan's Quintet
    Annotated image
  • Arp 319, or Stephan's Quintet, is a visual group of five galaxies.
  • The brightest galaxy, NGC 7320, is much closer to us and is not
  • a gravitational member of the group.  The other four galaxies,
  • NGC 7318a, NGC 7318b, NGC 7319, and NGC 7320, are
  • gravitationally bound and are located 280 Mly from us.
  • NGC 7331 is the larger spiral galaxy in the top right.
  • It is located approximately 40 Mly from us.
  • Hover over the picture for an annotated version
  • Date:  29 September, 18 and 27 October 2022, and 15 September 2023
  • FOV:  cropped to 75' × 50'; the long axis of Stephan's Quintet is about 5'
  • Telescope:  Stellarvue SVX102T + SFFX-1 flattener (714mm, f/7)
  • Guiding:  ZWO ASI120MM mini mono guide camera,
  • Stellarvue F050G 50mm guide scope
  • Computer:  ASIair pro Raspberry Pi
  • Mount:  iOptron CEM40
  • Camera:  ZWO ASI071MC Pro Cooled (-10°C) Color CMOS with gain 240
  • Pixel size:  4.78 μm
  • Resolution:  1.337 arcsec/pixel
  • Frames:29 Sept 2231 × 240 seconds,
  • 18 Oct 2244 × 240 seconds,
  • 27 Oct 2252 × 240 seconds,
  • 15 Sept 2394 × 240 seconds
  • Filter:  Baader Light Pollution Moonglow filter with IR cut
  • Stacking:  Two-hundred-twenty-one 240 second frames using Pixinsight
  • Calibration frames:  20 dark, 20 flat, 20 dark flat for each session
  • Total Time:  14 hours 44 minutes
  • Processing:  Pixinsight – SPPC, DBE, SPCC, BlurXT, NoiseXT, DynCrop → Linear
  • MStr, GHS, HST, PMath MStr + GHS + HST → Stars, Sat,
  • StarXT, MStr, GHS, HST, PMath MStr + GHS + HST → Starless,
  • HDR444PhLm, Sat, PMath ~(~Stars*~Starless) → Blend, scale
  • Location:  Darling Hill Observatory near Vesper, NY