DRAFT
2024-12-23 14:07:10
Type: Object/s-Discovery/Classification
Bibcode: 2024TNSAN.381....1S
Discovery of BGEM J132515.39-425833.7 / AT 2024aeql : Nova or early SN in Centaurus A / NGC5128
Authors: Simo Scaringi (Durham), Gavin Ramsay (Armagh), Hugo Tranin (Barcelona), Jan van Roestel (Amsterdam), Paul Groot (Radboud/UCT/SAAO), Paul Vreeswijk (Radboud), Steven Bloemen (Radboud), Danielle Pieterse (Radboud), Danny Steeghs (Warwick), Martin Dyer (Sheffield), David O'Neill (Warwick)
Source Group: BlackGEM
Keywords: Time-domain, Surveys, Photometry, Transient, Optical, Nova, Supernova
Abstract:
BGEM J132515.39-425833.7 / AT2024aeql was recently discovered by the BlackGEM and GOTO telescope arrays at q/L =18.5. The object is located ~2' NW of the core of Centaurus A / NGC 5128, at a distance of 3.5 Mpc. Identification spectroscopy and follow-up photometry is highly encouraged to establish the astrophysical nature of this nearby transient.

Discovery of BGEM J132515.39-425833.7 / AT2024aeql : Nova or early SN in Centaurus A / NGC5128

On behalf of the BlackGEM and GOTO consortia, we report the discovery of BGEM J132515.39-425833.7 ([1], https://www.wis-tns.org/object/2024aeql), located approximately 2 arcminutes northwest of the core of Centaurus A (NGC 5128), a Seyfert 2 galaxy at a distance of 3.5 Mpc. Finding charts and magnitude information are available in the corresponding TNS report.

Additionally, we report two BlackGEM [2] detections with magnitudes i = 18.07 +/- 0.11 and q = 18.41 +/- 0.07, respectively at 3 and 24 minutes after the initial detection at q = 18.47  +/- 0.05 on 2024-12-23 08:20:36 UT. GOTO [3] forced photometry also reveals a detection in the GOTO L band (400-700nm) of L = 18.51 +/- 0.16 on 2024-12-19 17:25:43 UT.

The latest non-detections are as follows: 

- BlackGEM: 2024-07-29 23:31:04 UT with a 5-sigma q > 20.68

- MeerLICHT:  2024-08-17 17:16:29 UT with a 5-sigma detection limit for transients at q > 18.45

- GOTO: 2024-12-12 17:12:07 UT with a 5 sigma upper limit of L > 19.0

Assuming Cen A to be the host galaxy of the transient, we infer the q-band (440-720nm) absolute magnitude of BGEM J132515.39-425833.7 to be approximately -9.25 mag. This is at the bright end of the range for classical nova peak absolute magnitudes [4], though we cannot rule out the possibility of an early phase supernova or a luminous red nova. Between the first GOTO and the first BlackGEM detection (~3.5 days) the transient remained approximately constant in brightness. 

Due to the proximity of Centaurus A and the intrinsic brightness of this source, we strongly encourage multi-wavelength follow-up observations.

All BlackGEM, MeerLICHT and GOTO magnitudes are in the AB system. 

[1] Tranin, H. et al., 2024, TNS Astronomical Transient Report No. 236825

[2] Groot, P.,J. et al., 2024, PASP, 136, 115003

[3] Steeghs, D.T.H. et al., 2022, MNRAS 511, 2405

[4] Shara et. al. 2023, ApJS, 269, 42

 

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 2024aeql 13:25:15.395 -42:58:33.75 13:25:15.395 -42:58:33.75 Nova 0.002
File Comments
tns_2024aeql_atrep_236825_BlackGEM.pdf BlackGEM Finder chart

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