DRAFT
2025-08-30 13:40:47
Type: Object/s-Discovery/Classification
Bibcode: 2025TNSAN.275....1W
GOTO-FAST spectroscopic classifications of optical transients
Authors: I. Worssam, M. Pursiainen, T. Killestein, J. Lyman, D. O'Neill, K. Ackley, M. Dyer, K. Ulaczyk, D. Steeghs, D. Galloway, V. Dhillon, P. O'Brien, G. Ramsay, K. Noysena, R. Kotak, R. Breton, J. Casares, L. Nuttall, B. Godson, A. Kumar on behalf of GOTO collaboration
Source Group: GOTO
Keywords: Transient, Supernova, Optical, Spectroscopy
Abstract:
This report includes classifications of 6 SNe Ia, 1 SN Ic-BL, and 1 SN II. We draw particular attention to three objects: SN2025wfz, a candidate SLSN, AT2025seu, a candidate luminous fast cooler event, and SN2025wej, a young flash-ionised SN.

GOTO-FAST reports the classifications of the following optical transients. The observations were obtained on the Nordic Optical Telescope (NOT) on the nights of 2025 Aug 28 and 2025 Aug 29 using the ALFOSC spectrograph with Gr4 grating (3200-9600 Å, R ~360). The transients were classified using SNID-SAGE (Stoppa 2025), SNID (Blondin & Tonry 2007) and GELATO (Harutyunyan et al. 2008). 

Targets were  supplied by the Gravitational-wave Optical Transient Observer GOTO (Steeghs et al. 2022, Dyer et al. 2024) and the Zwicky Transient Facility ZTF (Bellm et al. 2019) - data stream processed through the ALeRCE broker (Forster et al. 2020)

The classified objects are listed below in the Related Objects Table.

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 2025wfz [ATLAS25ktd] 23:20:04.670 +16:17:02.90 SN Ic-BL 0.3 Reasonable quality matches are obtained to templates of SNe Ic-BL at z=0.3, with no convincing matches found assuming the source is at the redshift (z=0.024) of the nearby galaxy. The bumps present are not well explained by e.g. Halpha and Hbeta at this closer redshift. Further follow-up is encouraged to concretely determine the nature of this transient: at z=0.3, the transient would have a peak absolute magnitude of -21.7 mag, compatible with being a SLSN. 23:20:04.673 +16:17:02.89 SN Ic-BL 0.3
TNS 2025ttp [ATLAS25jiz] 20:16:27.732 +10:19:51.13 SN Ia 0.06 Best matches obtained with templates of normal SNe Ia around 1 week post-peak. Redshift estimated from template matching, and concordant with photo-z of host galaxy. 20:16:27.732 +10:19:51.13 SN Ia 0.06
TNS 2025wej [ZTF25abmtjsr] 22:58:20.052 +02:17:36.02 SN II 0.016155 UGC 12271 0.016155 Matches to young SN II. A bump around 4600A is consistent with the typical flash-ionised emission from N/C in young SN II. Strong galaxy lines contaminate the spectrum. Redshift from host (NED) 22:58:20.052 +02:17:36.04 SN II 0.016155
TNS 2025vlw [GOTO25ggw] 01:28:22.508 -35:59:28.40 SN Ia 0.018199 ESO 353- G 005 0.018199 Good matches are obtained to templates of SNe Ia (with some plausible matches to 91bg- and 02es-like subtypes). Redshift corresponds to the host galaxy spectroscopic redshift via NED. 01:28:22.484 -35:59:28.21 SN Ia 0.018199
TNS 2025vnv [ZTF25abllldx] 23:31:34.096 +46:18:16.93 SN Ia 0.04 Best matches obtained to templates of SNe Ia around 1 week pre-peak. Redshift estimated from template matching. 23:31:34.084 +46:18:16.80 SN Ia 0.04
TNS 2025txi [ATLAS25jmc] 02:05:25.282 -30:46:15.08 SN Ia 0.073954 WISEA J020525.22-304615.6 0.073954 Good template matches obtained to SNe Ia around 1-2 weeks post-peak. Redshift corresponds to spectroscopic redshift of host galaxy, obtained via NED - also consistent with narrow host H and [S II] lines seen in spectrum. 02:05:25.285 -30:46:14.90 SN Ia 0.073954
TNS 2025wau [ZTF25ablnmoq] 02:15:49.320 +19:21:24.49 SN Ia 0.15 Good template matches for SNe Ia around peak. Redshift estimated from template matching. 02:15:49.320 +19:21:24.49 SN Ia 0.15
TNS 2025tqz [GOTO25fte] 04:22:38.070 -06:24:33.33 SN Ia 0.06 Best matches were obtained to SNe Ia around 7 days post-peak. Redshift obtained from template matching. 04:22:38.070 -06:24:33.33 SN Ia 0.06
TNS 2025seu [GOTO25fkt] 17:53:30.565 +61:46:38.99 Other 0.2544 A candidate SLSN as reported in AstroNote 2025-270 (I. Pérez-Fournon et al.). Object shows a blue continuum resulting in the ambiguous classification. Candidate luminous, fast cooler (Nicholl et al. 2023) based on the light curve, spectrum and the passive host galaxy. 17:53:30.565 +61:46:38.99 0.2544
AstroNote Publication Timestamp Title Authors
2023-224 2023-08-14 15:35:44 GOTO-FAST spectroscopic classifications of optical transients B. Godson, B. Warwick, D. O'Neill, J. Lyman, T. Killestein, M. Pursiainen, D. Coppejans, G. Ramsay, R. Kotak, K. Ackley, M. J. Dyer, K. Ulaczyk, F. Jiminez-Ibarra, A. Kumar, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. P. Breton, L. K. Nuttall, E. Pall'e, D. Pollacco on behalf of GOTO
2025-270 2025-08-28 12:58:42 AT 2025seu: a superluminous supernova candidate in the red galaxy DESI J268.3778+61.7777 at a redshift of z = 0.2544 I. Pérez-Fournon (IAC and ULL), D. Cano-Morales (ULL), F. Poidevin (IAC and ULL), B. Armas-Chinea, I. Correa-Plasencia, A.E. Hernández-Díaz, M. Quintana-Ansaldo, E. Lekaroz-Urriza (ULL), C. Jiménez Ángel (GRANTECAN), R. Shirley (MPE), R. Marques-Chaves (Univ. of Geneva), and S. Geier (GRANTECAN & IAC)

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