RW Cephei 12th and 24th December 2022

I decided to have a go at observing a different variable star this month and that is RW Cephei. The star is located near the triangle of stars made by zeta, delta and epsilon Cephei (the "foot" at the base of the constellation's main rhombus of stars). RW is a red hypergiant whose apparent brightness ranges between 6.0 and 7.6 over a period of about 346 days. It is classified as a semi-regular SRd type. Earlier this month this star has become the focus of attention because it may be going through a period of exceptional dimming as did Betelgeuse in Orion in January 2020.

I had a look at this star on Monday the 12th December 2022 in the early evening. At this time the moon was 4 days past full and not due to rise until 19:32 UT. At 18:30 the sky was clear and dark and astronomical twilight had just ended.

At 18:32 UT RW was fainter than star E (=7.3 mag.) on chart 312.02. At 18:50 UT I thought it was marginally brighter than star H (=7.8 mag.) and my estimate was E(2)V(1)H or magnitude 7.6 (to 1 d.p.).

I had another go at this star a few days ago on Christmas Eve (24th December). Then it was just one day past new moon and again the sky was clear and dark but there may have been a slight mist.

At 18:45 UT RW was again fainter than star E (=7.3 mag.) but this time it was closer brightness to this star than star H (=7.8 mag.). My estimate at 18:55 UT was that it was E(1)V(2)H or magnitude 7.5. So not much different to 12 days ago.

I don't have much to compare my results to as there hasn't been any further data added to the BAA VSS database by other observers since the 10th December, though one BAA VSS member did say that he had measured it to be visual magnitude 7.7 on the 21st December (via baavss-alert).

All text and images © Duncan Hale-Sutton 2022