Abstract
LE01
The HKU--NJU Lobster Eye 01 (LE01) telescope, China's first dedicated wide-field X-ray monitoring satellite, is characterised through its first systematic in-orbit performance assessment. Although LE01 meets design specifications for angular resolution (≤ 20″), energy resolution (≤ 200 eV), spectral range (0.4-10keV), and field of view (≥ 2° × 2°), the measured effective area of only 1.6 cm², far below the requirement of 25–50 cm², renders the telescope insufficient for substantive scientific observations of faint sources. To address the data processing challenges posed by the telescope's characteristic cruciform point-spread function, we nonetheless develop a purpose-built framework comprising an iterative 3σ attitude redirection algorithm and a cruciform-PSF-adapted source detection pipeline, validated through Crab Nebula observations (SNR = 9.98) and gamma-ray burst monitoring, establishing a methodological foundation for China's next generation of lobster-eye X-ray missions.
XPNe science
Given the limitations of LE01, the scientific analysis of X-ray emitting planetary nebulae (XPNe) is conducted using eROSITA, XMM-Newton, and Einstein Probe data. X-ray emission has been detected in fewer than 1% of the ≈4,000 known Galactic planetary nebulae (PNe), yet the physical conditions driving this rare phenomenon remain poorly understood. Statistical analysis of 42 confirmed XPNe against 2,739 general PNe from the HASH database reveals that XPNe are both morphologically and physically distinct: over 92\% are bipolar or elliptical in morphology (vs. 65% in the general population), with systematically higher electron temperatures (Tₑ = 13,601 ± 3,831 K) and electron densities consistent with shocked wind-driven environments.
eROSITA + EP discoveries
Cross-matching the eROSITA eRASS1 all-sky survey with the HASH catalogue via a purpose-built four-phase selection pipeline confirms seven XPNe, including two new discoveries: IC 1297 and NGC 2867, both hosting Wolf-Rayet central stars, suggesting a physical link between carbon-oxygen enriched stellar winds and detectable X-ray emission. An independent cross-match against the 4XMM-DR14 serendipitous source catalogue finds that 44% of matched PNe are soft X-ray dominant, indicating that the true prevalence of X-ray emission substantially exceeds the known confirmed sample. Einstein Probe follow-up spectroscopy of IC 1297, the most distant XPNe known to date at a Gaia parallax distance of 4.13 kpc, yields a plasma temperature of 𝑘𝑇 = 0.183−0.038+0.034 𝑘𝑒𝑉 (≈ 2.1 × 10⁶ K) and an X-ray luminosity of Lₓ = 2.7 × 10³¹ erg s⁻¹, consistent with a wind-driven hot bubble model and representing one of Einstein Probe's Cycle 2 scientific results.
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