OBSERVERS CHALLENGE – JANUARY, 2021
by Glenn Chaple
IC 348– Cluster and Reflection Nebula in Perseus (Mag: 7.3, Size: 8’)
IC 348 is a star-forming region in Perseus, located just 7 arc-minutes south and slightly east of the magnitude 3.8 star omicron (ο) Persei. It contains several hundred stars, most of which are too faint to be seen with typical backyard scopes. The cluster illuminates the surrounding reflection nebula VdB 19. Visually, a small-aperture scope will capture a dozen or so of the brighter cluster members, while the nebulosity mandates medium to large apertures and a dark-sky location.
In her book Deep-Sky Wonders, Sue French mentions a triple star, Σ439, and a double star, Σ437, that are associated with IC 348. In most scopes, Σ439 appears as a magnitude 8.8 and 10,3 double separated by 23.4”. The brighter star is actually a tight binary system (BD+31°643) whose magnitude 9.3 and 9.5 components, both hot B5-type main sequence stars, are just 0.6” apart. Σ437 is a near twin system comprised of magnitude 9.8 and 10.0 stars separated by 11.4”.
IC 348 is a young open cluster, perhaps no more than 2 million years old. Cluster and nebula are 900 to 1000 light years away.
*The purpose of the Observer’s Challenge is to encourage the pursuit of visual observing. It is open to everyone who is interested. If you’d like to contribute notes, drawings, or photographs, we’ll be happy to include them in our monthly summary. Submit your observing notes, sketches, and/or images to Roger Ivester (rogerivester@me.com). To find out more about the Observer’s Challenge or access past reports, log on to rogerivester.com/category/observers-challenge-reports-complete.
IC 348 Finder Charts
IAU and Sky and Telescope
Chart made using AAVSO’s Variable Star Plotter. Numbers are magnitudes, decimals omitted. Field of view is 1.0 by 0.5 degrees. North is up. Bright star is omicron Persei.
Taken with 32-inch scope using asi6200 camera. About 90 minutes total imaging, 30 minutes each red/green/blue. North is up. Image by Mario Motta (ATMoB)
IC 348, as seen with 10-inch f/5 reflector at 141X. Field is o0.6 degrees across. Sketch by Glenn Chaple (ATMoB)