U Sco unexpected 2022 eruption

Observed: 10, 11 Jun, 2 Jul 2022

Michel Bonnardeau
13 Jun 2022
Updated 3 Jul 2022

Abstract

A few photometric light curves are presented for the well known recurrent nova U Sco that went in eruption in June 2022.

Introduction

U Sco, a well known recurrent nova, was observed as going into an eruption on 6 Jun 2022. This was somewhat unexpected as the recurrence interval is around 10 years and the previous erruption was in 2016. Actually, the last eruptions were 1999, 2010, 2010, 2016 (lost inside the solar gap, but kink in the eclipse O-C, see AAVSO, 2022), and now 2022, so the last 2 eruptions are 6 years apart.

Observations

The observations were carried out with a 203 mm f/6.3 Schmidt-Cassegrain telescope, a Johnson V filter, and a camera with a KAF401E CCD. I made time series with individual exposures of 200 s.

For the differential photometry, the comparison star is GSC 6205-00320 with the UCAC4/APASS magnitudes V=10.592 and B-V=0.648 (so the spectral type should be G0-G5). The check star is GSC 6206-01000.

I obtained 158 measurements, in 3sessions. The results are shown in the figures below:

Green: U Sco, Black: check star, shifted by -0.3 mag. The error bars are ± the 1-σ statistical uncertainties. The Moon, 3.x days past First Quarter, is at 36°.

The check star is shifted by +0.3 mag. The Moon is at 23°. The short interruption was due to haze/cloud.