Collinder 399 – Brocchi’s Cluster

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Collinder 399 - Brocchi's Cluster

Collinder 399 (also known as Brocchi’s Cluster) is pretty unusual.  6 bright stars appear in a row with three below.  Most of the bright blue stars are type A stars while the lower 2 are a M type star and a K type star.  I was able to capture a bit of Spectra from them as well , across HIP95560, HIP95582 and HIP95498.  Several dark nebulae sit in the surrounding area as well.

Location

Location:  Pendleton, Oregon
Observatory:  ASG Dual Dome Observatory
Bortle:  4

Equipment

Telescope: Celestron RASA 11 (620mm focal @ f/2.2)
Filters:  Astronomik MaxFR 50x50mm Square SHO & Deep Sky RGB
Main Camera:  ZWO ASI 6200mm-pro Monochrome
Tilt & BackFocus Adjuster:  ASG Electronically Assisted Tilt (EAT)
Mount:  iOptron CEM 120EC
Guide Scope:  William Optics 50mm Uniguide
Guide Camera:  ZWO ASI 290mm-mini
Processing Software:   Captured with NINA, Stacked with Astro Pixel Processor,  Processed in PixInsight

Acquisition

Date:  June, 2025

R:  60 x 180 seconds
G:  60 x 180 seconds
B:  60 x 180 seconds

Total Integration time ~9 hrs

Calibration Bias: 20
Calibration Dark: 20
Calibration Flats: 20 for each filter