2 papers
math.FA2025
A counterexample of the Fredholm of Toeplitz operator
Hua Liu, Xinyang Zhang
In this paper we study the essential spectra of the Toeplitz operator on the Hardy space . We give a counterexample to show that the Toeplitz operator with symbol is not Fredh…
astro-ph.EP2025
The Spectrum of C/2023 A3 Indicates A Depleted Composition
Yunyi Tang, Shihao Wang, Zixuan Lin +4
We report a spectroscopic observation of comet C/2023 A3 using an 80 mm apochromatic (apo) refractor equipped with a custom-built spectrometer with a resolution of R~2,500 on the n…