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We report the results of new transit observations for the three hot Jupiter-like planets HATP-36b, HATP-56b and WASP-52b respectively. Transit timing variations (TTVs) are presented for these systems based on observations that span the period 2016 - 2020. The data were collected with the 0.6 m telescope at Adiyaman University (ADYU60, Turkey) and the 1.0 m telescope at T\"UB\.ITAK National Observatory (TUG, Turkey). Global fits were performed to the combined light curves for each system along with the corresponding radial velocity (RV) data taken from the literature. The extracted parameters (for all three systems) are found to be consistent with the values from previous studies. Through fits to the combined mid-transit times data from our observations and the data available in the literature, an updated linear ephemeris is obtained for each system. Although a number of potential outliers are noted in the respective O-C diagrams, the majority of the data are consistent within the 3$\sigma$ confidence level implying a lack of convincing evidence for the existence of additional objects in the systems studied., Comment: Accepted for publication in MNRAS

Black hole transients are known to undergo spectral transitions that form q-shaped tracks on a hardness intensity diagram. In this work, we use archival RXTE data to extract a characteristic minimal timescale for the spectral states in GX 339-4 for the 2002-3, and 2010 outbursts. We use the extracted timescale to construct an intensity variability diagram for each outburst. This new diagram is comparable to the traditional hardness intensity diagram and offers the potential for probing the underlying dynamics associated with the evolution of the relevant emission regions in black hole transients. We confirm this possibility by connecting the minimal timescale with the inner disk radius, $R_{in}$ (estimated from spectral fits), and demonstrate a positive correlation between these variables as the system evolves through its spectral transitions. Furthermore, we probe the relation between the minimal timescale and the break frequencies extracted from the power spectral densities. Lastly, we examine a possible link between the extracted timescale and a traditional measure of variability i.e., the root mean square, determined directly from the power spectra., Comment: Accepted for publication in MNRAS

Full list of authors: Gupta, Rahul; Oates, S. R.; Pandey, S. B.; Castro-Tirado, A. J.; Joshi, Jagdish C.; Hu, Y. -D; Valeev, A. F.; Zhang, B. B.; Zhang, Z.; Kumar, Amit; Aryan, A.; Lien, A ; Kumar, B.; Cui, Ch; Wang, Ch; Dimple; Bhattacharya, D.; Sonbas, E.; Bai, J.; Tello, J. C.; Gorosabel, J.; Castro Ceron, J. M.; Porto, J. R. F.; Misra, K.; De Pasquale, M.; Caballero-Garcia, M. D.; Jelinek, M.; Kubanek, P.; Minaev, P.; Cunniffe, R.; Sanchez-Ramirez, R.; Guziy, S.; Jeong, S.; Tiwari, S. N.; Razzaque, S.; Bhalerao, V.; Pintado, V. C.; Sokolov, V. V.; Zhao, X.; Fan, Y.; Xin, Y.

Using a wavelet decomposition technique, we have extracted the Hurst exponent for a sample of 46 long and 22 short Gamma-ray bursts (GRBs) detected by the Gamma-ray Burst Monitor (GBM) aboard the Fermi satellite. This exponent is a scaling parameter that provides a measure of long-range behavior in a time series. The mean Hurst exponent for the short GRBs is significantly smaller than that for the long GRBs. The separation may serve as an unbiased criterion for distinguishing short and long GRBs.

We present a direct link between the minimum variability time-scales extracted through a wavelet decomposition and the rise times of the shortest pulses extracted via fits of 34 Fermi Gamma-ray Burst Monitor (GBM) Gamma-Ray Burst (GRB) light curves comprised of 379 pulses. Pulses used in this study were fitted with lognormal functions, whereas the wavelet technique used employs a multiresolution analysis that does not rely on identifying distinct pulses. By applying a corrective filter to published data fitted with pulses, we demonstrate agreement between these two independent techniques and offer a method for distinguishing signal from noise.

Spectral lag, which is defined as the difference in time of arrival of high and low energy photons, is a common feature in Gamma-ray Bursts (GRBs). Previous investigations have shown a correlation between this lag and the isotropic peak luminosity for long duration bursts. However, most of the previous investigations used lags extracted in the observer-frame only. In this work (based on a sample of 43 Swift long GRBs with known redshifts), we present an analysis of the lag-luminosity relation in the GRB source-frame. Our analysis indicates a higher degree of correlation -0.82 +/- 0.05 (chance probability of ~ 5.5 x 10^-5) between the spectral lag and the isotropic peak luminosity, Liso, with a best-fit power-law index of -1.2 +/- 0.2, such that Liso proportional to lag^-1.2. In addition, there is an anti-correlation between the source-frame spectral lag and the source-frame peak energy of the burst spectrum, E_pk(1+z).