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comet and spectroscopic observations on 27 march 2025

it was a nice sunny day, towards evening high veil clouds appeared and disappeared late in the evening. However, it remained a low transparent sky. A few comets could be observed, with my 0.4-m f/3.8 newtonion telescope, including: 29P, C/2022 QE78, C/2023 H5 and C/2023 Q1, all images with photometric Bessel-R filter. With the 11″ Cassegrain telescope and LHiReSS III spectrograph I was able to capture spectra of PZ Gem ( 7 x 1200 sec exposure) in high resolution in H-alpha region. All my spectra could be seen and free downloaded in the BeSS-database after they are approved.

comet and spectroscopic observations on 17 march

after a sunny day, we also got a clear night with low temperatures around freezing. Transparency was initially reasonable with SQM in zenith of 18.7 to go to 19.2 later in the evening/night and drop back as the moon came out. Comets that could be observed with my 0.4-m f/3.8 Newtonion telescope were: 29P, 496P, P/2019 Y3, C/2022 E2, C/2023 H5, C/2023 Q1, C/2025 D1 (not detected in background of magn. 20.3). With the 2nd observatory ( 0.28-m f/10 cassegrain telescope with LHiReSS-III spectrograph), high resolution spectra of H-alpha region were obtained from PZ Gem (exposure: 8 x 1200 sec) and 4 Her (exposure: 3 x 1200 sec)

manuscript “The birth of Be star disks… ” published

The paper made by Jonathan Labadie-Bartz was today published: “The birth of Be star disks I. from localized ejection to circularization”; abstract:

Classical Be stars are well known to eject mass to build up a disk, but the details governing the initial distribution and subsequent evolution of this matter into a disk are in general poorly constrained through observations.
Aims. By combining high-cadence time-series spectroscopy with contemporaneous space photometry from the Transiting Exoplanet Survey Satellite (TESS), we have sampled about 30 mass ejection events in 13 Be stars. Our goal is to constrain the geometrical and kinematic properties of the ejecta as early as possible