a=40–56′ (joint fit of two extracted annuli) · No independent BKG region: jointly fit foreground + SrcApec in the source region

XSherpa joint fit of all receipt-published MOS spectra: all-ObsID data with 1σ errors, per-spectrum best-fit totals, global components, combined sky/source excluding MOS instrumental lines/SP, per-spectrum MOS instrumental lines/soft protons, and per-spectrum Δχ with errors.

The fit continuously covers 0.4–7.2 keV; grouping is XARTATOMS net S/N ≥ 6 with RMF FWHM oversampling ≤ 6, forcing a new bin at model/instrumental-line boundaries. Display units are sb_flux (counts s^-1 keV^-1 cm^-2 arcmin^-2); every MOS dataset resolves an independent flat-response SP, and non-zero terms are drawn as thin semi-transparent blue-grey dotted lines. SP fitted as exactly zero does not fabricate a line on the log axis and is explicitly counted in the public manifest. In these units the SP curve is a detector-space pseudo-SB. MOS instrumental lines are evaluated with the same Python-scalar skyarea prefactor as the saved full model; every non-zero line trace is checked against the all-line full-model reference value of the same session.

Region definition:a=40–56′ does not fabricate a new PHA; this page jointly fits the two receipt-published spectral sets a040_048 and a048_056 with SrcApec shared.

Controlled no-BKG strategy: first fit the foreground with SrcApec norm=0;next release only SrcApec norm with kT=0.7 keV fixed and save that session; only then release SrcApec kT to 0.5–1 keV, constrain MWhalo kT≤0.35 keV, and keep SrcApec abundance=1 frozen.

This is a new project-internal XSherpa derivative. The current baseline has not reached equivalent PLOT_QUALIFIED certification of the original project; figures and sessions are pure replots from the saved fit artifacts of this run and are never refit or regrouped during plotting.

Terminal fit parameters

Formal errors：NOT_COMPUTED。The saved terminal fit artifact contains no Sherpa confidence result; this page reports best-fit values and configured bounds only, with no fabricated errors.

Retained intermediate solution: srcapec_norm_fixed_kT_0p7

Foreground was first fitted with SrcApec.norm=0. This capture then releases only SrcApec.norm while SrcApec.kT=0.7 keV is frozen.

χ²=8397.98；dof=3131；reduced χ²=2.682

Terminal fit parameters

Formal errors：NOT_COMPUTED。The saved terminal fit artifact contains no Sherpa confidence result; this page reports best-fit values and configured bounds only, with no fabricated errors.

Parameter	best fit	Unit	configured bounds	State
LHB norm	2.85912e-06	XSPEC apec norm	3.00000e-07 – 1.00000e-04	fixed
MWhalo kT	0.246654	keV	0.1 – 0.35	fixed
MWhalo norm	2.42120e-06	XSPEC apec norm	5.00000e-07 – 1.00000e-05	fixed
MWhotHalo norm	0	XSPEC apec norm	0 – 1.00000e-05	fixed
CXB norm	0.00248064	XSPEC pegpwrlw norm	1.00000e-05 – 0.1	fixed
SrcApec kT	0.7	keV	0.5 – 1	fixed
SrcApec norm	1.96869e-08	XSPEC apec norm	0 – 1.00000e-04	free