2026dwm | Transient Name Server

RA/DEC (2000)

09:38:54.025 -04:51:37.97

144.7251044 -4.8605483

Type

SN IIb

Redshift

0.022

Discovery Report Classification Report

Reporting Group

GOTO

Discovering Data Source

GOTO

Discovery Date

2026-02-21 12:08:03.840

TNS AT

Y

Public

Y

Discovery Mag

19.97

Filter

L-GOTO

Reporter/s

D. O'Neill, K. Ackley, M. Dyer, J. Lyman, K. Ulaczyk, D. Steeghs, D. Galloway, V. Dhillon, P. O'Brien, G. Ramsay, K. Noysena, R. Kotak, R. Breton, J. Casares, L. Nuttall, R. Starling, B. Gompertz, B. Godson, T. Killestein, A. Kumar, M. Pursiainen, on behalf of GOTO collaboration

NED SIMBAD DECaLS PanSTARRS-1 SkyMapper VizieR WISE DSS ADS

Light curves

▌

GOTO-S_GOTO-3_L

▌

P48_ZTF-Cam_i

▌

P48_ZTF-Cam_g

Pointer position (MJD, Mag, Abs.Mag): (0.00, 0.00, 0.00)

Spectra

Select	ID	Obs-date (UT)	Tel / Inst	Exp-Time	Observer/s	Reducer/s	Group	Spectrum ascii file	Spectrum fits file	Spec. Type	Assoc. Groups	End prop. period	Remarks
	23098	2026-02-26 00:57:59	VLT-UT1 / FORS2	750	service	G. Csoernyei	adH0cc	tns_2026dwm_2026-02-26_00-57-58.849_VLT-UT1_FORS2_adH0cc.asci	tns_2026dwm_2026-02-26_00-57-58.849_VLT-UT1_FORS2_adH0cc.fits	Object			Quick-reduction spectrum
Binning factor: (rounded to nearest integer >1) Mouse hovers at WL: 0 (rest), 0 (observed) ▌Show H at z=v_exp= km/s ▌Show He at z=v_exp= km/s ▌Show He II at z=v_exp= km/s ▌Show C II at z=v_exp= km/s ▌Show C III at z=v_exp= km/s ▌Show C IV at z=v_exp= km/s ▌Show N II at z=v_exp= km/s ▌Show N III at z=v_exp= km/s ▌Show N IV at z=v_exp= km/s ▌Show N V at z=v_exp= km/s ▌Show O at z=v_exp= km/s ▌Show [O I] at z=v_exp= km/s ▌Show O II at z=v_exp= km/s ▌Show [O II] at z=v_exp= km/s ▌Show [O III] at z=v_exp= km/s ▌Show O V at z=v_exp= km/s ▌Show O VI at z=v_exp= km/s ▌Show Na at z=v_exp= km/s ▌Show Mg at z=v_exp= km/s ▌Show Mg II at z=v_exp= km/s ▌Show Si II at z=v_exp= km/s ▌Show S II at z=v_exp= km/s ▌Show Ca II at z=v_exp= km/s ▌Show [Ca II] at z=v_exp= km/s ▌Show Fe II at z=v_exp= km/s ▌Show Fe III at z=v_exp= km/s ▌Show Å at z=v_exp= km/s ▌Show Å at z=v_exp= km/s ▌Show Å at z=v_exp= km/s ▌Show Å at z=v_exp= km/s ▌Show Tellurics ▌Show Galaxy lines at z= ▌Show WR-WN at z=v_exp= km/s ▌Show WR-WC/O at z=v_exp= km/s Remarks Quick-reduction spectrum

Light Curves

Filter

Tel / Inst

Obs-date range

JD Range

Photometry

L-GOTO

GOTO-S_GOTO-3

2026-02-11 12:28:05 - 2026-02-21 12:08:04

2461083.019495 - 2461093.005598

2

Photometry

ID	Obs-date	JD	Mag. / Flux	Err	Lim. Mag./Flux	Units	Filter	Tel / Inst	Exp-time	Observer/s	Remarks
560011	2026-02-21 12:08:04	2461093.005598	19.97	0.14		ABMag	L-GOTO	GOTO-S_GOTO-3	180
560010	2026-02-11 12:28:05	2461083.019495			20.5	ABMag	L-GOTO	GOTO-S_GOTO-3	180		[Last non detection]

i-ZTF

P48_ZTF-Cam

2026-02-14 09:06:11 - 2026-02-24 09:26:54

2461085.879294 - 2461095.8936806

2

Photometry

ID	Obs-date	JD	Mag. / Flux	Err	Lim. Mag./Flux	Units	Filter	Tel / Inst	Exp-time	Observer/s	Remarks
561170	2026-02-24 09:26:54	2461095.8936806	19.2404	0.138047		ABMag	i-ZTF	P48_ZTF-Cam
561169	2026-02-14 09:06:11	2461085.879294	19.576	0.114352		ABMag	i-ZTF	P48_ZTF-Cam

g-ZTF

P48_ZTF-Cam

2026-02-14 08:27:46 - 2026-02-14 08:27:46

2461085.8526157 - 2461085.8526157

1

Photometry

ID	Obs-date	JD	Mag. / Flux	Err	Lim. Mag./Flux	Units	Filter	Tel / Inst	Exp-time	Observer/s	Remarks
561168	2026-02-14 08:27:46	2461085.8526157			20.5059	ABMag	g-ZTF	P48_ZTF-Cam			[Last non detection]

AT Reports

ID	Time received (UT)	Sender	Reporter/s	Reporting group	Disc. Data Source	RA	DEC	Discovery date (UT)	Discovery Mag.	Filter	Related files	AT Type	Host name	Internal name	Assoc. Groups	End prop. period	Remarks	ADS Bibcode	Unreal	Auto classification
292742	2026-02-24 11:10:05	Fritz	Jesper Sollerman (SU), Christoffer Fremling (Caltech), Daniel Perley (LJMU) et al.	ZTF	ZTF	09:38:54.025	-04:51:37.97	2026-02-14 09:06:11.001	19.576	i-ZTF		PSN		ZTF26aahrmfb	ZTF				N
292194	2026-02-22 10:17:07	GOTO_bot	D. O'Neill, K. Ackley, M. Dyer et al.	GOTO	GOTO	09:38:54.005	-04:51:38.24	2026-02-21 12:08:03.840	19.97	L-GOTO		Other		GOTO26big	GOTO			2026TNSTR.736....1O	N

Classification Reports

ID

Time received (UT)

Sender

Classifier/s

Group

Classification

Redshift

Spectra

Related files

Assoc. Groups

End prop. period

Remarks

ADS Bibcode

23097

2026-02-26 12:07:13

Geza Csornyei

G. Csoernyei, B. Leibundgut, J. Spyromilio, S. Blondin (ESO), S. Taubenberger (TUM / MPA), W. Hillebrandt (MPA)

adH0cc

SN IIb

0.022

1

adH0cc

The spectrum shows prominent P Cygni features of H and He, along with a strong Ca triplet at early phases, indicative of a Type IIb supernova. We find good matches with the spectra of 1993J a few days after maximum light assuming E(B-V) = 0.3 mag. Redshift measured based on host galaxy emission lines.

2026TNSCR.848....1C

Spectra

ID	Obs-date (UT)	Tel / Inst	Exp-Time	Observer/s	Reducer/s	Group	Spectrum ascii file	Spectrum fits file	Spec. Type	Assoc. Groups	End prop. period	Remarks
23098	2026-02-26 00:57:59	VLT-UT1 / FORS2	750	service	G. Csoernyei	adH0cc	tns_2026dwm_2026-02-26_00-57-58.849_VLT-UT1_FORS2_adH0cc.asci	tns_2026dwm_2026-02-26_00-57-58.849_VLT-UT1_FORS2_adH0cc.fits	Object			Quick-reduction spectrum

Comments

Object coordinates updated

Object coordinates updated according to AT-report 292742 of Group ZTF
Previous RA, DEC: 09:38:54.005, -04:51:38.24 (144.72502, -4.860622)
Updated RA, DEC: 09:38:54.025, -04:51:37.97 (144.7251044, -4.8605483)

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