S Coronae Borealis (S CrB)
Description and References
S Coronae Borealis is one of several well-known variable stars in the Northern Crown. A Mira-type variable, S CrB has a visual magnitude range 5.3-13.6 and a period of 360 days. This M6.5-8e star is an easy one to monitor over the course of a year. I have labeled five reference stars in the Origin image in order of decreasing visual magnitude. The action buttons will take you to detailed information on all six stars in the Simbad Database. Here are two references for S CrB:
- S and U Coronae Borealis, Sky & Telescope Volume 75(6), June 1988, p. 631
- Observing Variable Stars, David H. Levy, Cambridge University Press, Cambridge, UK, 1989, p. 142
Logbook
- Date & Time: August 11, 2024, 10:46 pm
- Location: Kempt Shore, Nova Scotia, Canada, 45°N
- Conditions: Clear, calm
- Moon: Waxing crescent (41%), moonset 10:48 am
- Technical: 10-sec exposures, 10-min integration, line power, no filter, no post-processing
S CrB dimming
After 216 days S CrB has become very faint. It was similar in magnitude to reference star 2 (HD 1366544) back in August 2024 when it was near its maximum, but now it is closer to reference star 4 (BD+31 2726A). It will continue to dim for another 3 months or so before increasing in magnitude faster than it dimed.
Logbook
- Date & Time: March 14, 2025, 5:14 am
- Location: Kempt Shore, Nova Scotia, Canada, 45°N
- Conditions: Partly cloudy, calm, -4°C
- Moon: Full moon (100%), moonset 7:23 am
- Technical: 10-sec exposures, 10-min integration, line power, no filter, no post-processing