Hoag's object (Serpens)

Object image
Fig.1 - Puzzling ring of fire: Hoag's object PGC 54559 in Serpens, photographed with a 16-inch f/4.5 Dob on an equatorial platform.
Object name: Constellation: Coordinates: Apparent size: Visual brightness:
Hoag's object (PGC 54559) Serpens 15h17m / +21°35' 0.28' x 0.28' 16.4 mag

The ring galaxy PGC 54559 (Hoag's object) in the constellation Serpens. The non-typical galaxy is named after the American astronomer Arthur Hoag (1921-1999) who discovered it in 1950 and identified it as either a planetary nebula or a peculiar galaxy.

A ring of young hot blue stars with an apparent outer diameter of 45" (121,000 light-years) circles the older yellow nucleus with an apparent outer diameter of 6" (17,000 light-years) of this ring galaxy. Hoag's object is approximately 600 million light-years from Earth (source: Wikipedia).

Forty-eight 3-minute exposures (146 minutes total exposure) at ISO 800 taken on May 25 / 26, 2020 were added for this shot with the DeepSkyStacker software and the final image processing was done in Photoshop.

Equipment: Canon EOS 450D Baader modified camera, TeleVue Paracorr Type II coma corrector, 16" f/4.5 "Ninja" dobsonian telescope riding on a dual-axis Tom Osypowski equatorial platform, Lacerta MGEN autoguider, Lacerta off axis system (field of view comparison: image of the moon with the same equipment).

Search chart
Fig.2 - Overview star chart for Hoag's object. Map © 2020 "The Mag-7 Star Atlas Project", www.siaris.net. Map is slightly modified. The star map can be downloaded here. Use the more detailled chart below (Fig.3) to find Hoag's object.
Search chart
Fig.3 - More detailled chart for Hoag's object: Star hopping from the constellation Corona Borealis to Hoag's object with a 50 mm finder scope. Use this chart to center Hoag's object. Then use Fig.1 (which measures just 24' x 36') to identify stars close to the object. Note: None of the stars in Fig.3 can be seen in Fig.1 (the field of view of the photograph is too small).