HCT followup observations of SN2026ejy.

ATel #17708; Dipang Vaishnav (Indian Institute of Astrophysics, Bangalore, India), F. Sutaria (Indian Institute of Astrophysics, Bangalore, India) and Alak Ray (Homi Bhabha Center for Sceince Education-TIFR, Mumbai, India) )
on 5 Mar 2026; 14:49 UT
Credential Certification: Firoza Sutaria (fsutaria@iiap.res.in)

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We report on the spectroscopic followup of SN2026ejy (O’Neill et al., 2026, TNSDiscovery Report, 2026-804:1., and, Jha et al., 2026, TNS Classification Report, 2026-850:1) taken on 2026-02-28 UTC 23:12:26 from the Himalayan Chandra Telescope (HCT). The UV continuum still dominates the spectrum. The flash-ionized features detected on 2026-02-25 (SALT/RSS DLT40 spectrum, TNS id 23097) have weakened, but are still visible for H-alpha, while the O II 6720 A feature has faded. Besides the H-alpha and H-beta flash-ionized features, we also detect a narrow feature ($v \simeq 1000$ km s^{-1}$), which could be a blend of O IV 4778, 4784 A lines. The fading of the O II line in our spectrum suggests that it may have originated in the flash ionized, circumstellar, low velocity, clouds at short radial distance from the exploding progenitor.

The photospheric temperatures estimated from black body fits to the spectra show considerable cooling from $\simeq 13900$ K (on 2026-02-25) to $\simeq 9200$ K (on 2026-02-28). The photospheric radius, based on an estimated distance of 25.7 Mpc (Jha et al. (2026)) is $\simeq 4000$ R_sun. Applying the Supernova Identification (SNID) code (Blondin and Tonry, 2007, ApJ, 666, 1024) on our spectrum, we confirm that SN2026ejy is a Type II (most likely a type IIP) event which best matches the template of SN1999em at -2.6 days before peak.

We thank the HCT scheduled observers and staff for enabling the observations.