01 Oct – zodiacal light for the next two weeks – a broad triangular patch of light extending up and right from the eastern horizon before sunrise

02 Oct 04:14 UTC minor planet Asponna (246) mag 13 occults star UCAC4 440-003139 mag 12.2 for up to 4.6 seocnds

02 Oct – New Moon (14:49EDT)

05 Oct – Thin crescent Moon 4º below Venus (mag -3.9) very low in the SW sky after sunset

06 Oct 09:17UT minor planet (812) Adele occults star TYC 2417-00070-1 (mag 10.5) for up to 1.1s for people along the St Lawrence River.

07 Oct – Moon 2º left of Antares after sunset

10 Oct – First Quarter Moon

12 Oct – Comet C/2023 A3 Tsuchinshan-ATLAS reappears in the western sky after sunset

17 Oct – Full Moon (07:26EDT)

20 Oct – Orionid meteor shower peaks, waning gibbous Moon interferes

23 Oct – Comet C/2024 S1 (ATLAS) (mag 10?) closest approach to Earth

24 Oct – Last Quarter Moon

28 Oct – Comet C/2024 S1 (ATLAS) (mag -5?) at perihelion

Comet C/2023 A3 Tsuchinshan-ATLAS

After spending the first ~2 weeks of the month too close to the Sun to be visible comet C/2023 A3 reappears in the evening sky after sunset. It rises rapidly each evening higher above the western horizon. On the 12^th it is at its closest approach to Earth and is also relatively close to the Earth-Sun line so forward scattering of sunlight may enhance the visibility of the tail. Over the last two weeks of the month it races almost straight eastward through Serpens Caput and Ophiucus.

Comet C/2024 S1 (ATLAS)

This comet was discovered recently by the ATLAS (Asteroid Terrestrial-impact Last Alert System) survey. It is a member of the Kreutz sungrazer group of comets which pass very close to the surface of the Sun, generally being destroyed in the process. However this one appears to be larger than average so has a small chance of becoming a ‘great’ comet. It starts the month in Hydra, very faint, low and getting lower in the SE during morning twilight, but also getting brighter. It passes closest to Earth on the 23^rd and reaches perihelion (closest to the Sun) on the 28^th. If it survives passage through perihelion it will stay low in the SE during morning twilight but could be very bright. This comet will be much better seen from the southern hemisphere.