DRAFT
2023-06-30 14:11:53
Type: Object/s-Discovery/Classification
Bibcode: 2023TNSAN.191....1S
Identification and classification of the fast and blue transient AT2023lya as a likely Ibn supernova
Authors: S. Srivastav, M. Fulton (QUB), M. E. Huber, B. J. Shappee (IfA), S. J. Smartt (Oxford/QUB), M. Nicholl, T. Moore, X. Sheng, K. W. Smith, D. R. Young (QUB), H. Stevance, L. Rhodes (Oxford), T.-W. Chen (TUM), J. Sommer (LMU), K. C. Chambers , A. S. B. Schultz, T. de Boer, J. Bulger, J. Fairlamb, H. Gao, C. C. Lin, T. Lowe, E. Magnier, P. Minguez, I. A. Smith, R. J. Wainscoat (IfA)
Source Group: OxQUB
Keywords: Transient, Optical
Abstract:
We report follow-up observations of the fast and blue transient AT2023lya, discovered by ZTF (ZTF23aapuknd). The combined ZTF, ATLAS, LT and PS1 photometry indicates a rapid rise ( > 1.2 mag/day) with a short rise time ( < 5 days) and a blue colour, (u - g) ~ -0.3. A SNIFS spectrum indicates SN Ibn as the likely classification.

We report follow-up photometric and spectroscopic observations of the blue and rapidly rising transient AT2023lya, discovered by ZTF (ZTF23aapuknd) on MJD 60122.28 (2023-06-27.28 UTC) at r = 20.07 +/- 0.31. Through the Lasair broker (Smith et al. RNAAS, 3,26 2019; https://lasair-ztf.lsst.ac.uk/objects/ZTF23aapuknd/) and ATLAS transient server (Smith et al. 2020), we identified this as a rapidly rising transient associated with a SDSS galaxy with a photometric redshift of z=0.047 ± 0.022. 

ZTF reported a non-detection 2 days prior on MJD 60120.38 at r > 20.5. The transient rose by ~2.5 mag in g and r bands in subsequent ZTF observations on MJD ~60124.40, indicating a rapid rise of >1.2 mag/day. We detected AT2023lya in ATLAS on MJD 60124.41 at an orange-band mag of o = 17.60 ± 0.03. Follow-up imaging with the Liverpool Telescope and Pan-STARRS1 between MJD 60125.20 - 60125.40 suggests the transient is close to peak, indicating a short rise time of ~5 days. The photometry indicates a (u - g) colour of ~ -0.3, confirming AT2023lya as a fast and blue transient. 

A spectrum was obtained on MJD 60125.38 with the SNIFS instrument on the University of Hawaii 2.2-meter Telescope (UH88). The spectrum reveals a blue continuum and narrow emission features identified as HeII 4686 and H-alpha/HeII 6560 at a redshift z ~ 0.03.

The combined ZTF, ATLAS, LT and PS1 photometry and follow-up photometry from Balam et al. (AstroNote 2023-190) indicates a peak absolute mag Mg ~ -18.5 at this redshift. Together with the spectrum, we favour a Ibn classification for AT2023lya.

Show current TNS values
Catalog Name Reported RA Reported DEC Reported Obj-Type Reported Redshift Host Name Host Redshift Remarks TNS RA TNS DEC TNS Obj-Type TNS Redshift
TNS 2023lya [ZTF23aapuknd] 17:28:53.264 +58:22:41.62 SN Ibn 0.03 SDSS J172853.58+582238.9 17:28:53.215 +58:22:41.53 SN II 0.03

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