Abell S0805

Constellation: Pavo

Abell s0805 is a galaxy cluster in the constellation of Pavo. Its brightest galaxy is IC 4765. Link to interactive sky chart.

The candidate supernova AT2025tpu was caught during image acquisition. AT2025tpu is located in the host galaxy IC 4769, and about 189 million Ly away (58 Mpc). Below is the comparative image (luminance channel) of the galaxy IC 4769 taken on July 28, 2025 and August 23, 20205.

Related scientific publication: AstroNote 2025-254 (Link).

AT2025tpu: Possible very young supernova in IC4769 at 58 Mpc

Authors:P.J. Groot (Radboud/UCT/SAAO), E. Zimmerman (Weizmann), H. Tranin (Barcelona), J. van Roestel (Amsterdam), P.M. Vreeswijk (Radboud), S. Bloemen (Radboud), J. Paice (Durham), F. Stoppa (Oxford), G. Ramsay (Armagh/Warwick)

Source Group:BlackGEM

Keywords:Optical, Photometry, Supernova, Time-domain, Transient

Abstract:

A very young supernova candidate, AT2025tpu, is reported by the BlackGEM consortium in the Seyfert 2 galaxy IC 4769 at 58 Mpc. The transient was first detected at q=19.25 and confirmed to be brightening during the night. A one-day upper limit of q >19.68 is set the previous nights with non-detections in multiple images. IC 4769 is also the host galaxy of SN2004ac, a type Ia supernova.

The BlackGEM consortium reports the detection of BGEM J184740.50-630939.4 /AT2025tpu at RA,DEC (ICRS) = 281.918767 -63.160972. The transient was first detected at 2025-08-12 00:34:44 UT at q=19.25 +/- 0.07, and subsequently brightened on a second visit at 2025-08-12 01:50:14 to q=19.00 +-/- 0.09. The last non-detection of the source was on 2025-08-11 03:21:54 UT at a 6-sigma limit for transients of q>19.68 as the last of four multi-band visits during that night, where the source was detected in none of the images.

AT2025tpu is located in the outskirts of the Seyfert 2 galaxy IC 4769 at a distance of 58 Mpc and at 28″ from the center of IC4769 in an uncrowded region of the galaxy. Adopting the distance of IC4769 for the transient, it is currently at an absolute magnitude of -14.8. We note that IC4769 was also host to SN2004ac, a Type Ia supernova.

Spectroscopic identification of this young transient is requested.

BlackGEM is designed, built and operated at the ESO La Silla Observatory, Chile by a consortia of universities and institutes, including
Radboud, NOVA, KU Leuven, Armagh, Barcelona, Tel Aviv, Weizmann, HUJI, Potsdam, Hamburg, DTU Space, Manchester, Warwick, Durham, UC Davis, TexasTech, LCO, Valparaiso.

Dates:

This is derived from the outstanding data taken by Martin Pugh during July and August 2025 (Martin’s website: Remote Astrophotography with Martin Pugh (martinpughastrophotography.space).

His telescope is located in Chile (Observatory: El Sauce).

Colour palette is LRGB.

Telescope & Mount:

Planewave CDK24 on a Planewave L600 mount.

Imaging:

Camera: Moravian C1-61000 (bin 2×2)

Data:
Astrodon L: 15x600s
Astrodon R: 17x600s
Astrodon G: 24x600s
Astrodon B: 23x600s

Total integration time: 13h 10′