Observing session on Comet P10/Tempel during an earthquake at the Kottamia Astrophysical Observatory (MPC Q62, Egypt)
ATel #17942; Mohamed Aboushelib (National Research Institute of Astronomy and Geophysics, Egypt), Abdelaziz Eid (National Research Institute of Astronomy and Geophysics, Egypt), Costantino Sigismondi (ICRANet and UPRA, Rome Italy), Federico Manzini (Stazione Astronomica di Sozzago, Italy), Raoul Behrend (Observatoire de Geneve, Switzerland), Virginio Oldani (Stazione Astronomica di Sozzago, Italy), David Augustin (Anglet, France), Luigi R. Bedin (OAPdâINAF, Italy)
on 5 Aug 2026; 13:38 UT
Credential Certification: Costantino Sigismondi (sigismondi@icra.it)
On the night of 3 August 2026 at 00:00:37 UTC, a strong earthquake of magnitude 5.4 struck Egypt, with its epicenter near the Kottamia Astronomical Observatory, 83.5 km to the northeast. The event was recorded by the INGV seismometer network and reported by the control center in Rome.
https://terremoti.ingv.it/en/event/46752922
It was also detected by NRIAG (Egypt) seismometers.
https://ensn.nriag.sci.eg/en/origins/1046/event
That same night, the Kottamia 1.88 m telescope was used by the team led by Mohamed Aboushelib of NRIAG, under the guidance of Federico Manzini, to observe Comet 10P/Tempel as it approached perihelion at 1.418 AU on 2 August 2026 and perigee at 0.414 AU on 4 August 2026. Nightly observations since May 2026 have revealed the morphology of Comet 10P's inner coma, including jets, shells, and fans, supporting analysis of its rotation period (ATel 17831).
Images acquired during the earthquake are available here:
https://web.oapd.inaf.it/bedin/files/PAPERs_eMATERIALs/ATel/10P/
and https://docs.google.com/presentation/d/1O44wDk_MW0H52MU995R_Y7hlCi59Ku31/edit?usp=sharing&ouid=115860204555202031936&rtpof=true&sd=true
The images show the earthquake's effects: the telescope moved, causing a sudden shift in pointing along a path visible in the frame. The seismic shock produced a sharp gap between two bright images separated by 18.67 arcsec at a position angle of 176.41 degrees. These measurements were derived from all sufficiently bright Gaia stars in the field of view. The bright star below the comet is TYC 6956-94-1, with magnitudes V=10.87 and B=11.44.
The observing night of 3 August 2026 concluded the Kottamia Observatory campaign on Comet 10P, which began on 22 May 2026.
Accompanying material on Comet 10P/Tempel
