Key Takeaways:
- The article identifies the California Nebula (NGC 1499) in southern Perseus as a primary observational target, noting its optimal viewing period when it reaches 45° altitude by 11 P.M. local daylight time, peaking around 3 A.M.
- Illuminated by the 4th-magnitude star Xi (ξ) Persei, this nebula spans approximately 2.5° by 0.5° and possesses a low surface brightness despite its overall magnitude 6.
- Effective visual observation of NGC 1499 necessitates dark skies and is considerably aided by a Hydrogen-alpha filter, while also being a favored subject for astrophotography.
- Additional celestial events for October 21 include the peak of the Orionids meteor shower, Comet Lemmon's closest approach to Earth, and a Titan transit, alongside local ephemeris data featuring a 3% waxing crescent Moon.
Looking for a sky event this week? Check out our full Sky This Week column.
October 21: The Orionids peak, Comet Lemmon is closest to Earth, and Titan makes a transit
With the sky clear of the nighttime Moon, try checking out the California Nebula (NGC 1499), located in southern Perseus. It reaches 45° in altitude by 11 P.M. local daylight time and is highest a few hours later, around 3 A.M.
You’ll find the California Nebula just 1° northeast of 4th-magnitude Xi (ξ) Persei — in fact, this star is the nebula’s light source, energizing the atoms of the cloud and making it glow. This huge nebula covers some 2.5° of sky along its long axis, and is 0.5° wide. Because it is so big, however, its overall surface brightness is very low; even though it glows at magnitude 6, you’ll need dark skies to capture it. Use a Hydrogen-alpha filter with your telescope to boost the nebula’s brightness against the background sky.
Although it is a bit difficult to observe visually, the California Nebula is a popular target for astrophotographers, so if you’ve got the setup, give capturing it a try.
Sunrise: 7:19 A.M.
Sunset: 6:10 P.M.
Moonrise: 8:31 A.M.
Moonset: 6:26 P.M.
Moon Phase: Waxing crescent (3%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. local time from the same location.
