Dear Author, Please check your proof carefully and mark all corrections at the appropriate place in the proof (e.g., by using on-screen annotation in the PDF file) or compile them in a separate list. Note: if you opt to annotate the file with software other than Adobe Reader then please also highlight the appropriate place in the PDF file. To ensure fast publication of your paper please return your corrections within 48 hours. For correction or revision of any artwork, please consult Any queries or remarks that have arisen during the processing of your manuscript are listed below and highlighted by flags in the proof. Click on the 'Q' link to go to the location in the proof. Location in article Query / Remark: click on the Q link to go Please insert your reply or correction at the corresponding line in the proof Q1 Please confirm that given name(s) and surname(s) have been identified correctly. Q2 Please check the telephone/fax number of the corresponding author, and correct if necessary. Q3 One or more sponsor names may have been edited to a standard format that enables better searching and identification of your article. Please check and correct if necessary. Q4 The country names of the Grant Sponsors are provided below. Please check and correct if necessary. 'NASA' -'United States', 'National Science Foundation' -'United States'. Q5 Please provide journal titles for 'Ref. [24]'. Thank you for your assistance. Please check this box if you have no corrections to make to the PDF file 1 3 Multi-wavelength study of Mrk 421 TeV flare observed with TACTIC 4 telescope in February 2010 5 6 7 a b s t r a c t 24 We present results from multi-wavelength study of intense flaring activity from a high frequency peaked 25 BL Lac object Mrk 421. The source was observed in its flaring state on February 16, 2010 with the TACTIC 26 at energies above 1.5 TeV. Near simultaneous multi-wavelength data were obtained from high energy 27 (MeV–GeV) c-ray observations with Fermi–LAT, X-ray observations by the Swift and MAXI satellites, opti-28 cal V-band observation by SPOL at Steward Observatory and radio 15 GHz observation at OVRO 40 meter-29 telescope. We have performed a detailed spectral and temporal analysis of TACTIC, Fermi–LAT and Swift– 30 XRT observations of Mrk 421 during February 10–23, 2010 (MJD 55237–55250). The flaring activity of the 31 source is studied by investigating the properties of daily light curves from radio to TeV energy range and 32 we present the correlation and variability analysis in each energy band. The TeV flare detected by TACTIC 33 on February 16, 2010 is well correlated with the activity in lower energy bands. The differential energy 34 spectrum of the source, in the energy range 1.5–11 TeV, as measured by TACTIC on this night is described 35 by a power law (dN=dE / E ÀC) with spectral index C ¼ 2:6 AE 0:3. After accounting for absorption of TeV 36 photons by low energy extragalactic background light photons via pair production, the intrinsic TeV spec-37 trum reveals a power law index of 2:3 AE 0:3. Finally the broad band spectral energy distribution of the 38 source in flaring state is reproduced using a simple emission model involving synchrotron and synchro-39 tron self Compton processes. The obtained parameters are then used to understand the energetics of the 40 source during the flaring episode. 41 Ó 2014 Published by Elsevier B.V. 42 43 44 45