ALMA and MeerKAT detection of radio rebrightening of SN 2007it

ATel #17830; A. Nucara (INAF-IAPS, UniRoma2), Z. J. Smeaton (Western Sydney Uni.), A. Simongini (INAF-OAR; UniRoma2), M. Arias (IAA-CSIC), on behalf of the RISE collaboration
on 4 Jun 2026; 14:00 UT
Credential Certification: Andrea Simongini (andrea.simongini@inaf.it)

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We report radio and millimeter detection of the Type II supernova SN 2007it in NGC 5530 (distance 12.2 Mpc), obtained as part of the Rebrightening in Interacting Supernova Emission (RISE) initiative.

Observations with the Atacama Large Millimeter/submillimeter Array (ALMA) were carried out on 2026 May 16 under Director's Discretionary Time (DDT). SN 2007it was detected at 40.15 GHz with a flux density of 1.83 +/- 0.15 mJy and 97.49 GHz with a flux density of 1.14 +/- 0.09 mJy. Observations with the MeerKAT radio telescope were obtained on 2026 May 2, also under DDT. SN 2007it was detected at 2.6 GHz with a flux density of 1.02 +/- 0.05 mJy.

These observations demonstrate that SN 2007it remains a luminous radio-to-millimeter source one month after previous radio detection (F. Acero et al 2026 Res. Notes AAS 10 103), consistent with ongoing interaction between the supernova ejecta and shells of circumstellar material.

Multi-wavelength follow-up observations are ongoing.

This ATel makes use of the following ALMA data: ADS/JAO.ALMA2025.A.00027.T. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSTC and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. We thank the directors of ALMA and MeerKAT for the award of the discretionary time that led to these observations.