Radio Detection of SN 2001ig in NGC 7424 with uGMRT Band 4 at 650 MHz
ATel #17888; Meghamala Bandyopadhyay (St. Xavierâs College, Kolkata; National Initiative on Undergraduate Science, Homi Bhabha Centre for Science Education-Tata Institute of Fundamental Research, Mumbai), Parth Sarfare (Thakur College of Science and Commerce, University of Mumbai; NIUS, HBCSE-TIFR), Akshat Singhal (Formerly, HBCSE-TIFR), Alak Ray (Formerly, TIFR), and Avinash Deshpande (Formerly, Raman Research Institute, Bengaluru)
on 13 Jul 2026; 16:31 UT
Credential Certification: Alak Ray (akr@tifr.res.in)
Subjects: Radio, Supernovae
We report a radio detection of the Type IIb supernova SN 2001ig in the nearby galaxy NGC 7424, at a distance of 10.8 Mpc (Soria et al. 2024), with the upgraded Giant Metrewave Radio Telescope (uGMRT).
The observation was carried out on 2026 May 20, from 01:30 to 03:30 UTC, in uGMRT Band 4, with a central frequency of 650 MHz and a bandwidth of 200 MHz. A two-component beam-shaped image-plane fit, including SN 2001ig and the nearby compact background radio source C-NGC7424, gives a fitted peak flux density of 20.8 +/- 1.0 mJy/beam at the SN position. The local source-free image rms near the SN position is approximately 129 microJy/beam. A relatively cleaner region away from the source gives a lower rms of approximately 45 microJy/beam. The quoted flux uncertainty includes the local rms noise and a 5 percent SN flux-density scale uncertainty added in quadrature.
A nearby compact background source, likely a background quasar, is detected at an angular separation of approximately 18.5 arcsec from SN 2001ig, with a fitted peak flux density of approximately 92 mJy/beam.
Previous low-frequency GMRT observations reported a 2-sigma upper limit of 2 mJy at 610 MHz for the SN from an observation obtained on 2001 December 31 (Poonam Chandra et al., IAU Circular 7994). The present uGMRT detection therefore indicates bright late-time low-frequency radio emission from SN 2001ig.
We thank the GMRT Team for assistance in carrying out the observations. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research.
