Variable optical emission from FSRQ 3C454.3: MIRO observations

ATel #6232; S. Chandra, KS Baliyan, Sanya & Deepti (Physical Research Laboratory, Ahmedabad, India)
on 14 Jun 2014; 07:31 UT
Credential Certification: Kiran S Baliyan (baliyan@prl.res.in)

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In the light of the recent telegrams related to enhanced activity in Gamma-rays(Atel#6182: AGILE flux at E> 100MeV ~ 2.4x 10^(-6) ph/cm^2/s during 2014, 25-27 May and Atel#6217: 10(-6) ph/cm^2/s during 2014, June 7-9) and NIR (Ate# 6213: J = 12.326(0.05), H = 11.498(0.05) and Ks = 10.527(0.05) on 2014, June 8) windows, we report our preliminary results from the four days monitoring of FSRQ 3C 454.3 (associated with Fermi source 2FGL 2253.9+1609) in the optical broad bands (IRVB) from Mt Abu InfraRed Observatory (MIRO) operated by the Physical Research Laboratory, Ahmedabad, India. The observations from 1.2m telescope, at MIRO, mounted with 1296x1252 pixels CCD were made during 2014 May 29 to June 1 (JD 2456805 - 2456808) in good sky conditions. Our observations, therefore, follow the first increased activity in Gamma-rays as reported by AGILE (Atel# 6182) and precede those reported via Atel# 6213 (NIR) and Atel # 6217(AGILE- Gamma-rays). We estimated the following values for optical brightness in 3C454.3 during our monitoring: 2014 May 29.9802 I=14.29(0.02) R=14.87(0.03) 2014 May 30.9667 I=14.31(0.02) R=14.88(0.02) V=15.28(0.04) 2014 May 31.9590 I=14.21(0.03) R=14.81(0.01) V=15.23(0.03) B=16.02(0.04) 2014 Jun 01.9603 I=14.19(0.02) R=14.73(0.02) V=15.15(0.02) B=15.91(0.03) From above data, it is clear that 3C454.3 was in brightening phase and exhibited day-to-day variability in all the optical bands. A mild bluer when brighter trend is seen, though within errors which implies a shock moving down the jet of turbulent plasma. The source, therefore, seems to be having correlated variations in Gamma-ray, optical and NIR fluxes, indicating to the co-spatial origin of these emissions, though more data are required to substantiate this conclusion. A long-term multi-wavelength monitoring of the source is suggested.