Optical spectra of SN 2023ixf with the HCT on 22nd May 2023.
ATel #16053; F. Sutaria (IIA, Bangalore) and Alak Ray (HBCSE/TIFR, Mumbai)
on 25 May 2023; 12:30 UT
Credential Certification: Firoza Sutaria (fsutaria@iiap.res.in)
Subjects: Optical, Supernovae
We report on spectroscopic observations of SN 2023ixf, taken with the Hanle Faint Object Spectrograph and Camera (HFOSC) mounted on the Himalayan Chandra Telescope (HCT), on 22nd May 2023 (MJD 60086.76755208), under our program HCT-2023-C2-P7/P8. The 3900-9200 A spectrum constitutes of a 720 s exposure in HFOSC/Gr7 (3900-6675 A, r=1330) and a 600 s exposure in HFOSC/Gr8 (6670-9200 A, r=2190). The spectra were flux calibrated relative to that of Feige 34, taken at similar airmass, on the same night.
The composite spectrum (Gr7 + Gr8) is dominated by the hot, UV, continuum, typical of young supernovae. The following emission features are detected:
(a) H-delta peaking at 4097.7 A, possibly blue shifted from rest wavelength of (4102 A),
(b) He II peaking at 4682.6 A, with a half-width velocity of 1280 km/s (approx.). It is superposed on a blend of C III triplet (4650 A) and [Fe III] (4658 A).
(c) H-beta, centered at 4857.6 A, with a half width velocity 1976 km/s (approx.),
(d) A possibly blue-shifted C IV doublet (5801/5811 A) at 5802.7 A, and,
(e) H-alpha centered at 6562.35 A, with a half width velocity 1325 km/s (approx.).
Additionally, we also find an absorption feature centered at 5893.1 A, corresponding to the galactic
Na D-doublet. The face-on M101 being at z=0.000804, any such feature from M101 would be faint, and, at the resolution of the HFOSC, indistinguishable from Milky Way's own absorption.
The HCT is a part of the Indian Astronomical Observatory (IAO) at Ladakh, operated by the Indian Institute of Astrophysics (Bangalore, India). We thank the staff at the IAO/HCT and at CREST for their support during the observations. We also thank the proposers of HCT 2023-C2-P04/P05 for sparing the ToO time.
