Richard, the 2024.4 (+/- 0.3) estimate does not come from Brad’s analysis of the intervals from these earlier eruptions, but from a comparison of the light curve over the last ~10 years with that leading up to the 1946 eruption. They show common features, like a “super active state”, pre-eruption dip. This is described here:
https://ui.adsabs.harvard.edu/abs/2023MNRAS.524.3146S/abstract
And refined here:
B.E. Schaefer, B. Kloppenborg, E.O. Waagen, “Recurrent Nova T CrB Has Just Started Its Pre-eruption Dip in March/April 2023, so the Eruption Should Occur Around 2024.4 +- 0.3,” The Astronomer’s Telegram, No. 16107 (2023). The SAO/NASA Astrophysics Data System.
His paper concerning his identification of much earlier outbursts ( https://ui.adsabs.harvard.edu/abs/2023JHA….54..436S/abstract ) says:
“T CrB has four observed eruptions in the years 1217.8, 1787.9, 1866.4, and 1946.1, plus one more expected upcoming in 2024.4 ± 0.3. The recurrence timescales are 7 × 81.4, 78.5, 79.7, and likely 78.3 ± 0.3 years. With nine eruptions from 1217.8 to 1946.1, the average recurrence timescale is 80.9 years.”
So the 78.3 +/-0.3 error bar comes from the first paper, not his analysis of the interval between the 4 known eruptions. This average timescale is 80.9 years (no error bar given).
Brad’s predictions are based on his assumption that the next eruption will unfold in the same way as the last two (which appear to have identical light curves). But there is no strong astrophysical reason that this should be the case a third time. As I’ve reported previously, other researchers have made predictions for later in 2024 or even Nov 2025. We shall just have to keep on looking.
