The Astronomer's Telegram: Top ATels

For reporting and commenting upon new observations of astronomical transients by the professional astrophysics community.

ATel 17827: A fast recent NIR flare of the Blazar CGRaBSJ1257+3229

We report on a recent fast NIR flare of the Blazar CGRaBSJ1257+3229, also known as QSO B1255+32 cross correlated with the gamma-ray source 2FGLJ1258.2+3231. ...
https://www.astronomerstelegram.org/?read=17827
date: 2026-06-02T16:06:47-00:00
creator: L. Carrasco, A. Porras,G. Escobedo, E. Recillas, L. Felix

ATel 17826: Discovery of a Probable Nova in M31, M31N 2026-06a

We report the discovery of a probable nova found during our survey of the central region of M31. The object was discovered on a co-added 600-s R-band CCD frame taken on 2026 Jun. ...
https://www.astronomerstelegram.org/?read=17826
date: 2026-06-02T02:24:58-00:00
creator: K. Hornoch, H. Kucakova, A. W. Shafter

ATel 17825: EP260530a/AT2026nwl: refined analysis of the EP-FXT observation

Following the detection of the X-ray transient EP260530a (Wu et al., ATel 17824), we performed a follow-up observation with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe mission. ...
https://www.astronomerstelegram.org/?read=17825
date: 2026-06-01T08:50:12-00:00
creator: W. F. Wen, C. Y. Dai, Q. Y. Wu, H. Sun

ATel 17824: EP260530a: Einstein Probe detection of an X-ray transient

We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission during an observation on 2026-05-30T07:29:02 (UTC), designated EP260530a. ...
https://www.astronomerstelegram.org/?read=17824
date: 2026-05-31T09:18:56-00:00
creator: Q. Y. Wu, C. Y. Dai, W. F. Wen, H. Sun on behalf of the Einstein Probe team

ATel 17823: Infrared Spectroscopy Confirms the Transition of IRAS 21204+4913 to an FU Ori Outburst

S. Kaneko first announced an optical transient that was associated by Grosso et al. (2025) in ATel #17546 with unstudied source IRAS 21204+4913. Kochkina et al. ...
https://www.astronomerstelegram.org/?read=17823
date: 2026-05-30T18:23:25-00:00
creator: E. Portnoi, L. A. Hillenbrand, A. S. Carvalho

ATel 17822: A dim host galaxy for FRB 20251229A: a FRB 20121102A host twin?

In ATel #17577, using CHIME/FRB Outriggers data, an elongated arcsecond-scale localization of the potentially hyperactive fast radio burst FRB 20251229A was reported (ATel #17574). ...
https://www.astronomerstelegram.org/?read=17822
date: 2026-05-29T18:13:06-00:00
creator: Luciano Nicastro, Andrea Rossi, Eliana Palazzi, Gabriele Bruni, Sandra Savaglio

ATel 17821: Fermi-LAT detection of a historic gamma-ray flare from OQ 334 with ASAS-SN optical brightening

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed enhanced gamma-ray flaring activity from a source positionally consistent with the flat-spectrum radio quasar (FSRQ) OQ 334 (B2 1420+326), also known as 4FGL J1422.5+3223 (Abdollahi et al., Fermi Large Area Telescope Fourth Source Catalog, ApJS, 247(1):33, 2020). ...
https://www.astronomerstelegram.org/?read=17821
date: 2026-05-29T12:51:57-00:00
creator: Sandeep Kumar Mondal, Avik Kumar Das ), Amar Deo Chandra

ATel 17820: Spectral softening of Cygnus X-3 observed with SVOM/ECLAIRs

We report a spectral softening of the microquasar Cygnus X-3 detected on 2026 May 27 by the ECLAIRs coded-mask instrument onboard the SVOM mission. The long-term ECLAIRs light curve had shown a progressive hardening of the source from 2026 March 30 until 2026 May 12. ...
https://www.astronomerstelegram.org/?read=17820
date: 2026-05-29T07:12:51-00:00
creator: S. Le Stum, F. Cangemi, A. Coleiro, S. Guillot, L. Zhang

ATel 17819: XRISM/Xtend Transient Search (XTS) detected an X-ray flare possibly from 2SXPS J232525.2+583935

XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J2325+5840 on 2026-5-26 TT. The source position is determined to be (R.A., Dec.) = (351.357, 58.660), with a systematic error of & sim; 40 arcsec. ...
https://www.astronomerstelegram.org/?read=17819
date: 2026-05-28T11:23:57-00:00
creator: T. Narita, H. Uchida, Y. Kanemaru, A. Miyamoto, Y. Omiya, Y. Uchida, T. Yoneyama, M. Audard, E. Behar, K. Fukushima, T. Hakamata, S. Inoue, Y. Ishihara, C. Kang, T. Kiyomoto, T. Kohmura, H. Kuramoto, Y. Maeda, H. Matsumoto, A. Miyamoto, M. Mizumoto, Y. Motogami, M. Nobukawa, H. Noda, S. Ogawa, Y. Sakamoto, M. Shidatsu, H. Takahashi, T. Takagi, S. Takatsuka, F. Takisawa, Y. Terada, Y. Terashima, Y. Tsuboi, A. Yoshimoto, M. Yoshimoto, P. P. Plucinsky

ATel 17818: Einstein Probe catches the onset of a new outburst from the NS LMXB MXB 1730-335 (Rapid Burster)

We report on the detection of a new outburst from the neutron star low-mass X-ray binary MXB 1730-335 (a.k.a. the Rapid Burster) with the Wide-field X-ray Telescope (WXT) onboard Einstein Probe (EP). ...
https://www.astronomerstelegram.org/?read=17818
date: 2026-05-27T15:18:27-00:00
creator: Alessio Marino, Francesco Coti Zelati, Nanda Rea, Yilong Wang, Giulia Illiano, Minghao Zhang, Chen Wang, Biao Zhang, Jiapei Feng, Haiwu Pan