AstroNote 2022-180

We report the discovery of a strongly lensed Type Ia supernova, SN2022qmx at redshift z=0.35 (hereby dubbed SN Zwicky), discovered by the Zwicky Transient Facility at Palomar Observatory under the Bright Transient Survey (BTS) program (Fremling et al, ApJ, 878, 5, 2020). The first detection of the SN was in a ZTF g-band image from 2022-08-01. It was saved to the BTS as a SN candidate by on-duty scanners on 2022-08-03 and subsequently assigned to the queue for spectroscopic follow-up with the SEDM Machine (SEDM) mounted on the Palomar 60-inch telescope (P60) under standard BTS protocols.  The SEDM spectrum, obtained 2022-08-21, shows an excellent match to a normal Type Ia supernova at a redshift of z=0.35 close to maximum light. The redshift and spectral classification were confirmed with a higher resolution spectrum obtained at the Nordic Optical Telescope on La Palma on the following night.

While the system is unresolved in our ground-based images, strong gravitational lensing is inferred since SN Zwicky is a spectroscopically normal Type Ia supernova, about 3 magnitudes brighter than unlensed SNe Ia at that redshift. Its current r-band magnitude is 18.7 mag.

Follow-up observations with HAWK-I and MUSE at VLT are ongoing, and space observations to resolve the multiple images have been requested. We encourage observers interested in coordinating follow-up observations to contact Ariel Goobar, ariel@fysik.su.se