A fast recent NIR flare of the Blazar CGRaBSJ1257+3229

ATel #17827; L. Carrasco, A. Porras ,G. Escobedo, E. Recillas, L. Felix (INAOE, Mexico)
on 2 Jun 2026; 16:06 UT
Credential Certification: LUIS CARRASCO (carrasco@inaoep.mx)

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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. On May24th, 2026 (JD2461184.8315), we found the object undergoing a large outburst. The NIR fluxes in the JHK bands were then: J=14.70 +/- 0.03, H=13.67 +/- 0.05 and Ks=13.07 +/- 0.05. While two days later, on JD2461186.7190 the H-band flux had decreased to H = 14.55 +/- 0.05, a factor of 2.2. This fact implies that the emitting zone is rather small less than two light days. Previously, the NIR fluxes in the H band on JD2461139.9695 and JD2460841.7855 had been H=15.180 +/- 0.055 and H=16.536 +/- 0.030, respectively. Hence, the object underwent an increase in the H band by a factor of 4 during the first lapse of forty five days and a factor of 14 during the last year. Ten years ago, the object showed a giant NIR flare reported on ATel#9084. Our observations are carried out with CANICA a NIR camera on the 2.1m telescope at the Observatorio Astrofisico Guillermo Haro, operated by the National Institute for Astrophysics, Optics and Electronics (INAOE, Mexico). We encourage further multiwavelength observations.