TNS Classification Report No. 8975 [ 2021TNSCR.511....1P ]
Date Received (UTC): 2021-02-18 20:55:51 Sender: Stefan Taubenberger
Group: adH0cc
A. Pastorello (INAF Padova), C. Vogl, S. Taubenberger, A. Floers, G. Csoernyei, M. G. Cudmani, A. Holas, W. Hillebrandt, S. H. Suyu (MPA Garching), S. Blondin (CNRS, LAM), B. Leibundgut, J. Spyromilio (ESO), S. J. Smartt, M. Dobson (QUB), R. Kotak (Turku), R. Bruch, A. Gal-Yam (Weizmann), C. Lemon (Lausanne) report/s a classification of object: SN 2021ckj
Type: SN IcnRedshift: 0.143
Remarks: An optical spectrum of SN 2021ckj, obtained on 2021 February 16 with the ESO Very Large Telescope UT1, the FORS2 spectrograph, and grism 300V, shows a blue continuum with a blackbody temperature of about 10000 K. The continuum is undulated by several broad (v > 10000 km/s) spectral lines, especially in the restframe range between 3500 and 5500 Å, reminiscent of SLSNe-I. Superimposed on this spectrum, one can find a series of narrow to intermediate-width lines (v = 1000 to 2500 km/s), some of them in emission, others exhibiting P-Cygni profiles. The lines can mostly be attributed to carbon: C III at 4650 Å and 5696 Å, and C II at 4267 Å, 5891 Å, 6580 Å and 7234 Å. He I 5875 Å is also detected. The redshift of the supernova of z = 0.143 has been measured from these narrow lines. A phase of 10d from explosion has been estimated from the combined ZTF and ATLAS light curves. With a rise time of merely a few days and a peak absolute g-band magnitude close to -20, SN 2021ckj is photometrically a fast blue optical transient (FBOT). Spectroscopically, it would be best characterised as a "Type Icn" supernova. Similarities with AT 2021csp (Perley et al., AstroNote 2021-62) should be investigated.
The following Classification spectrum was provided:
Obsdate: 2021-02-17 02:58:56
Instrument: FORS2
Telescope: The Very Large Telescope - UT1
Remarks: Quick-reduction spectrum, telluric corrections applied.
Details of the object and its spectra can be viewed here: https://sandbox.wis-tns.org/object/2021ckj
Date Received (UTC): 2021-02-18 20:55:51 Sender: Stefan Taubenberger
Group: adH0cc
A. Pastorello (INAF Padova), C. Vogl, S. Taubenberger, A. Floers, G. Csoernyei, M. G. Cudmani, A. Holas, W. Hillebrandt, S. H. Suyu (MPA Garching), S. Blondin (CNRS, LAM), B. Leibundgut, J. Spyromilio (ESO), S. J. Smartt, M. Dobson (QUB), R. Kotak (Turku), R. Bruch, A. Gal-Yam (Weizmann), C. Lemon (Lausanne) report/s a classification of object: SN 2021ckj
Type: SN IcnRedshift: 0.143
Remarks: An optical spectrum of SN 2021ckj, obtained on 2021 February 16 with the ESO Very Large Telescope UT1, the FORS2 spectrograph, and grism 300V, shows a blue continuum with a blackbody temperature of about 10000 K. The continuum is undulated by several broad (v > 10000 km/s) spectral lines, especially in the restframe range between 3500 and 5500 Å, reminiscent of SLSNe-I. Superimposed on this spectrum, one can find a series of narrow to intermediate-width lines (v = 1000 to 2500 km/s), some of them in emission, others exhibiting P-Cygni profiles. The lines can mostly be attributed to carbon: C III at 4650 Å and 5696 Å, and C II at 4267 Å, 5891 Å, 6580 Å and 7234 Å. He I 5875 Å is also detected. The redshift of the supernova of z = 0.143 has been measured from these narrow lines. A phase of 10d from explosion has been estimated from the combined ZTF and ATLAS light curves. With a rise time of merely a few days and a peak absolute g-band magnitude close to -20, SN 2021ckj is photometrically a fast blue optical transient (FBOT). Spectroscopically, it would be best characterised as a "Type Icn" supernova. Similarities with AT 2021csp (Perley et al., AstroNote 2021-62) should be investigated.
The following Classification spectrum was provided:
Obsdate: 2021-02-17 02:58:56
Instrument: FORS2
Telescope: The Very Large Telescope - UT1
Remarks: Quick-reduction spectrum, telluric corrections applied.
Details of the object and its spectra can be viewed here: https://sandbox.wis-tns.org/object/2021ckj