“the other Veil”
Sh2-91 is a faint and intricate supernova remnant located in the constellation Cygnus, sometimes called “the other Veil” or the Network Nebula. It forms part of the larger remnant SNR G65.3+5.7 (also cataloged as SNR 065.2+05.7), which stretches across approximately 310 × 240 arcminutes and is much larger than the well-known Veil Nebula nearby.
Key facts:
• Type: Supernova remnant (often misclassified in older catalogs as an H II region).
• Location: Cygnus, near the colorful star Albireo.
• Coordinates: RA 19h 35m 36s, Dec +29° 36’ 00” (J2000).
• Distance: Estimated between 800 parsecs (2,610 light-years) and 1,500 parsecs (4,890 light-years), based on different optical and extinction studies.
• Diameter: The whole SNR is about 70 parsecs (230 light-years) wide, and Sh2-91 is one of its prominent western filaments.
• Age: Estimated ~20,000 years old.
• Brightness: Much fainter than the Veil Nebula, requiring long exposures with narrowband filters to capture in detail.
• Notable star: Campbell’s Hydrogen Star (a rare WC-type star) appears near the center in many deep images.
Observation:
• Best seen from March to December, culminating at midnight in mid-July.
• Visible in deep astrophotography with prominent tangled filaments, especially using H-alpha and OIII filters.
Scientific notes:
• Sh2-91 is just a segment of the much larger supernova remnant, with other filaments labeled as Sh2-94 and Sh2-96.
• Proper motion and shock velocities indicate the remnant is still interacting with the surrounding interstellar medium, providing clues to both supernova physics and the structure of the galactic plane.
Photographic tips:
• Astrophotographers often dedicate many hours of exposure (10+ hours), primarily in H-alpha and OIII, to reveal its structure.
Sh2-91 offers a challenging but rewarding target for advanced imagers interested in rarely photographed, faint supernova remnants in the rich star fields of Cygnus.
ScopeHut Observatory 