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Long gamma-ray bursts (GRBs) frequently exhibit complex prompt-emission morphology, including a bright main-emission (ME) episode followed by a weaker extended-emission (EE) component. Whether these subcomponents are produced by the same central engine under different physical conditions remains unclear. Here, we present a systematic, pulse-resolved analysis of 24 Swift Burst Alert Telescope (BAT) long-duration GRBs that exhibit a well-separated ME episode (G<SUB>1</SUB>) followed by a fainter EE episode (G<SUB>2</SUB>) after a background-consistent quiescent interval. For each episode, we measure the episode-only duration (T<SUB>90</SUB>), count-based hardness ratio, minimum variability timescale (MVT), and spectral lag using the same Swift-BAT analysis pipeline adopted in Paper I. We find that the EE is typically softer and smoother than the ME: HR<SUB>EE</SUB> &lt; HR<SUB>ME</SUB> in 20 of 24 events, and MVT<SUB>EE</SUB> &gt; MVT<SUB>ME</SUB> in 19 of 24 events. The EE also shows a broader lag distribution, including both large positive and negative lags, although the sample-wide median lag offset is not statistically significant. Both episodes remain in the long-GRB track in the duration─hardness and duration─MVT planes. These results suggest that the EE in long GRBs may represent a physically distinct regime of the central engine, characterized by a lower luminosity, longer emission timescales, and softer spectral properties, rather than a simple continuation of the main burst. The observed trends are consistent with late-time central engine activity, such as fallback accretion onto a black hole or protomagnetar spin-down.

We present a broadband spectral analysis of the neutron star LMXB GRS 1747-312 using ∼ 40 ks Astrosat data. The source was observed during the decay phase of the 2017 outburst, with an absorbed 1.0─5.5 keV flux of <mml:math><mml:mrow><mml:mn>1</mml:mn><mml:mo>.</mml:mo><mml:msubsup><mml:mn>67</mml:mn><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.07</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>0.04</mml:mn></mml:mrow></mml:msubsup><mml:mo>×</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mrow><mml:mo>−</mml:mo><mml:mn>11</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math> erg s<mml:math><mml:msup><mml:mrow></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:math> cm<mml:math><mml:msup><mml:mrow></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:math>, corresponding to a luminosity of <mml:math><mml:mrow><mml:mo>∼</mml:mo><mml:mrow><mml:mo>(</mml:mo><mml:mn>0.9</mml:mn><mml:mo>−</mml:mo><mml:mn>1.80</mml:mn><mml:mo>)</mml:mo></mml:mrow><mml:mo>×</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mn>35</mml:mn></mml:msup></mml:mrow></mml:math> erg s<mml:math><mml:msup><mml:mrow></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:math>. The continuum is modeled with thermal Comptonization of blackbody emission and interstellar absorption. A mildly broad iron line at ∼ 6.4 keV is fitted with a disc reflection component. Narrow lines below 2 keV are described by a hot plasma using the xspec model apec. Additionally, there is a potential detection of an emission line at <mml:math><mml:mrow><mml:mn>4</mml:mn><mml:mo>.</mml:mo><mml:msubsup><mml:mn>19</mml:mn><mml:mrow><mml:mo>−</mml:mo><mml:mn>0.10</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>0.12</mml:mn></mml:mrow></mml:msubsup></mml:mrow></mml:math> keV with width <mml:math><mml:mrow><mml:mi>σ</mml:mi><mml:mo>=</mml:mo><mml:mn>0.2</mml:mn><mml:mo>±</mml:mo><mml:mn>0.2</mml:mn><mml:mspace></mml:mspace><mml:mtext>keV</mml:mtext></mml:mrow></mml:math> and line flux = <mml:math><mml:mrow><mml:msubsup><mml:mn>13</mml:mn><mml:mrow><mml:mo>−</mml:mo><mml:mn>9</mml:mn></mml:mrow><mml:mrow><mml:mo>+</mml:mo><mml:mn>10</mml:mn></mml:mrow></mml:msubsup><mml:mo>×</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mrow><mml:mo>−</mml:mo><mml:mn>5</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math> erg s<mml:math><mml:msup><mml:mrow></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:math> cm<mml:math><mml:msup><mml:mrow></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:math>. Examination of several short duration ( ∼ few kiloseconds) Swift observations at few times the AstroSat source flux, provided upper limits to the line flux <mml:math><mml:mrow><mml:mo>&lt;</mml:mo><mml:mn>30</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mrow><mml:mo>−</mml:mo><mml:mn>5</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math> erg s<mml:math><mml:msup><mml:mrow></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:math> cm<mml:math><mml:msup><mml:mrow></mml:mrow><mml:mrow><mml:mo>−</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:msup></mml:math>. The 4.2 keV line likely originates from reflection off the neutron star surface. Shifting the neutral Fe K<SUB>α</SUB> line from its rest energy of 6.4 to 4.2 keV requires a redshift of z ∼ 0.6, consistent with that expected from the surface of a non-spinning 1.4M<SUB>⊙</SUB>, 10 km radius neutron star. If confirmed, this feature provides a potential direct measurement of gravitational redshift, allowing us to place strong constraints on the neutron star's mass-to-radius ratio and gain valuable insights into the equation of state (EOS) of dense-matter.

Solar flare simulations are commonly initialised using nonlinear force-free field (NLFF) extrapolations derived from photospheric vector magnetograms. However, the force-free assumption neglects plasma forces and may limit the available free magnetic energy. In this work, we perform a controlled comparison of two three-dimensional resistive magnetohydrodynamic simulations of the X2.1-class flare that occurred on 2011 September 6 in NOAA Active Region 11283. The simulations differ only in their initial magnetic configuration: one is based on a conventional NLFF extrapolation, while the other employs a non-force-free extrapolation. Both models are evolved in an identical stratified atmosphere using the same numerical framework, enabling direct assessment of how the initial magnetic assumptions influence flare dynamics and energetics. We find that the non-force-free model undergoes more extensive magnetic restructuring and releases approximately twice as much magnetic energy (≍4.4 × 10<SUP>31</SUP> erg) as the NLFF case (≍2.3 × 10<SUP>31</SUP> erg), bringing the energy budget into closer agreement with expectations for X-class flares. Synthetic extreme-ultraviolet emission in the 94 Å channel is computed for both simulations and compared with observations from the Solar Dynamics Observatory. The non-force-free model produces a brighter and more spatially extended emission structure that more closely resembles the observed flare morphology and light curve. These results demonstrate that assumptions made in constructing the preflare coronal magnetic field can significantly affect flare energetics and observable signatures and suggest that non-force-free extrapolations provide a promising pathway toward more realistic data-constrained flare modelling.