Small Apparent Outburst of Comet 10P/Tempel 2
ATel #17985; Michael S. P. Kelley (Univ. Maryland), Thomas Lehmann (School Observatory Friedrich-Schiller-Gymnasium, Weimar, Germany), Carrie Holt (Las Cumbres Observatory), on behalf of the LCO Outbursting Objects Key Project
on 18 Aug 2026; 16:50 UT
Credential Certification: Carrie Holt (cholt@lco.global)
We report the discovery of a small apparent outburst of comet 10P/Tempel 2 on 2026 Aug 16 when the comet was 14 days after its perihelion, 1.4 au from the Sun, and 0.43 au from the Earth. The event was independently observed with telescopes at the Skygems Observatory Network (Namibia, MPC code L81) and with the Las Cumbes Observatory global telescope network.
Images of the comet were taken with a Takahashi FSQ 106 mm f/5 telescope and Green filter (495-600 nm bandpass) with a near-daily cadence in 2026 August. Each observation consisted of 4-6 individually calibrated images. The data were calibrated to Gaia DR3 BP magnitudes, including a linear color transformation term. Photometry in a 3,000 km (9.7 arcsec) radius aperture showed that the comet's apparent magnitude was 11.57+/-0.01 mag at 2026 Aug 16.08 UTC. By the time of the next observation, Aug 16.88 UTC, the comet had brightened to 11.37+/-0.01 mag, suggesting a mini-outburst with a relative strength of -0.20+/-0.01 mag. Observations taken later at the same night confirm the event, although the brightness had declined within the aperture: 11.45+/-0.01 mag at Aug 17.09 UTC. The next night the comet had already faded to the pre-outburst brightness: 11.58+/-0.01 mag at Aug 17.80 UTC.
The comet was also imaged with Las Cumbres Observatory's 1-m telescopes starting on 2026 May 01 with a near-daily cadence. Inspection of the most recent photometry taken with 1-m telescopes at Sutherland, South Africa further confirms the event. In SDSS r' filter images calibrated to the r band of the PS1 photometric system, the comet was 11.25+/-0.05 mag within a 10 arcsec radius aperture at 2026 Aug 16.10 UTC. At the time of the next observation, Aug 17.00 UTC, the comet brightened to 11.05+/-0.04 mag, and then declined back to 11.25+/-0.03 mag at Aug 17.98 UTC. Inspection of the temporally filtered data shows the ejecta distributed out to ~20 arcsec from the nucleus at Aug 17.00, and ~70 arcsec at Aug 17.98, corresponding to a maximum plane-of-sky expansion speed of ~200 m/s.
This work makes use of observations from the Las Cumbres Observatory global telescope network.
