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Optical/NIR Observations of HBL 1ES 1959+625 from Mt Abu IR Observatory(MIRO), India

ATel #9070; KS Baliyan(PRL, Ahmedabad), Sunil Chandra(TIFR, Mumbai), Navpreet Kaur, S. Ganesh, Sameer, M. Srivastava, V. Bisht, Jatin, Rathna Kumar (PRL, Ahmedabad)
on 20 May 2016; 13:45 UT
Credential Certification: Kiran S Baliyan (baliyan@prl.res.in)

Subjects: Infra-Red, Optical, X-ray, >GeV, AGN, Blazar, Quasar

Referred to by ATel #: 9139, 9148, 9203, 9239

We report the optical/NIR follow up observations of HBL 1ES 1959+650 (3FGL J2000.0+6509) at redshift (z) = 0.047 (Schachter et al. 1993, ApJ, 412, 541), using 1.2 m telescope at Mount Abu InrfaRed Observatory (MIRO), India after the alert from FACT collaboration (private communication) about TeV activity in this source. The preliminary analysis by FACT team has witnessed an enhanced flux (0.8 Crab) on 17th May 2016 (http://fact-project.org/monitoring/). Earlier, on 30th April 2016, this source was reported to be flared up in GeV-TeV (F_gamma ~ 0.2 X 10^-6 photons cm^-2 s^-1 and F_TeV ~ 1 Crab ) energies by FACT, VERITAS, MAGIC and Fermi Collaborations (ATel #9010). The source has been showing enhanced activity at almost all the energies, with X-rays showing highest count rate of 22.9 on Dec 26, 2015 (Atel# 8468), only the third blazar after Mrk 421 & Mrk 501 to show counts in 0.3 - 10 KeV more than 20 cts/s. The observations are made in J, H, K (NICS) and R, V (2kx2k CCD) bands using 1.2m telescope at MIRO. Following are the optical/IR apparent magnitudes of 1ES 1959+650. R V 13th May (UTC 22:20:17) 14.27+/-0.03 14.74+/- 0.02 14th May (UTC 22:33:07) 14.28+/-0.03 14.76+/-0.02 15th May (UTC 20:39:09) 14.28+/-0.01 14.78+/-0.01 19th May (UTC 19:53) 14.28+/-0.02 14.74+/- 0.02 J H K 18th May (UTC 22:55) 12.62 +/-0.04 11.97+/-0.06 11.64+/-0.23 These observations clearly show that the source maintains its high flux levels during these epochs of observations. IR brightness magnitudes are also comparable with those reported by 2MASS survey (AJ, 2006, 131, 1163). As can be inferred from the above magnitudes in optical/NIR, TeV activity reported by FACT-VERITAS and Fermi collaboration on May 17, 2016 either did not happen in optical (orphan flare in gamma-rays?) or subsided early as we missed observations on 16-17 May, 2016. Multi-wavelength monitoring of this interesting source is suggested.