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We present an in-depth study of a large and long duration ($>$1.3 days) X-ray flare observed on an RS CVn type eclipsing binary system SZ Psc using observations from Swift observatory. In the 0.35$-$10 keV energy band, the peak luminosity is estimated to be 4.2$\times$10$^{33}$ erg s$^{-1}$. The quiescent corona of SZ Psc was observed $\sim$5.67 d after the flare using Swift observatory, and also $\sim$1.4 yr after the flare using the XMM-Newton satellite. The quiescent corona is found to consist of three temperature plasma: 4, 13, and 48 MK. High-resolution X-ray spectral analysis of the quiescent corona of SZ Psc suggests that the high first ionization potential (FIP) elements are more abundant than the low-FIP elements. The time-resolved X-ray spectroscopy of the flare shows a significant variation in the flare temperature, emission measure, and abundance. The peak values of temperature, emission measure, and abundances during the flare are estimated to be 199$\pm$11 MK, 2.13$\pm$0.05 $\times 10^{56}$ cm$^{-3}$, 0.66$\pm$0.09 Z$_{\odot}$, respectively. Using the hydrodynamic loop modeling, we derive the loop length of the flare as 6.3$\pm$0.5 $\times 10^{11}$ cm, whereas the loop pressure and density at the flare peak are derived to be 3.5$\pm$0.7 $\times 10^{3}$ dyne cm$^{-2}$ and 8$\pm$2 $\times 10^{10}$ cm$^{-3}$, respectively. The total magnetic field to produce the flare is estimated to be 490$\pm$60 G. The large magnetic field at the coronal height is supposed to be due to the presence of an extended convection zone of the sub-giant and the high orbital velocity., Comment: 23 pages, 12 figures, 5 tables, accepted for publication in MNRAS

We present a comprehensive study of three large long-duration flares detected on an active M-dwarf binary EQ Peg using the Soft X-Ray Telescope of the AstroSat observatory. The peak X-ray luminosities of the flares in the 0.3 - 7 keV band are found to be within ~5 - 10 x 10^{30} erg s^{-1}. The e-folding rise- and decay-times of the flares are derived to be in the range of 3.4 - 11 and 1.6 - 24 ks, respectively. Spectral analysis indicates the presence of three temperature corona with the first two plasma temperatures remain constant during all the flares and the post-flare observation at ~3 and ~9 MK. The flare temperature peaked at 26, 16, and 17 MK, which are 2, 1.3, and 1.4 times more than the minimum value, respectively. The peak emission measures are found to be 3.9 - 7.1 x 10^{53} cm^{-3}, whereas the abundances peaked at 0.16-0.26 times the solar abundances. Using quasi-static loop modeling, we derive loop-lengths for all the flares as 2.5+/-0.5 x 10^{11}, 2.0+/-0.5 x 10^{11}, and 2.5+/-0.9 x 10^{11} cm, respectively. The density of the flaring plasma is estimated to be 4.2+/-0.8 x 10^{10}, 3.0+/-0.7 x 10^{10}, 2.2+/-0.8 x 10^{10} cm^{-3) for flares F1, F2, and F3, respectively. Whereas the magnetic field for all three flares is estimated to be <100 G. The estimated energies of all three flares are ~10^{34-35} erg, putting them in a category of superflare. All three superflares are also found to be the longest duration flares ever observed on EQ Peg., Comment: 11 pages, 3 figures, 3 tables, accepted for publication in MNRAS