Follow-Up Spectroscopy of Comet C/2023 A3
ATel #16911; M. Mugrauer
on 17 Nov 2024; 20:45 UT
Credential Certification: Markus Mugrauer (markus@astro.uni-jena.de)
In ATel #16887 spectroscopic observations of comet C/2023 A3 were reported, which were taken on four nights between 22 and 26 October 2024 with the Échelle spectrograph FLECHAS, installed at the Nasmyth port of the 90 cm reflector telescope of the University Observatory Jena. Strong emission lines of Na, [OI], NH2 and C2 were detected in the spectra of the comet's coma. The strength of the Na D1 & D2 emission lines weakened significantly during the observations as the heliocentric distance of the comet increased from about 0.75 to 0.82 au. Based on the observed decrease in the equivalent width of the Na emission lines, it can be estimated that the emission features of this alkali element in the spectrum of C/2023 A3 should no longer be observable after 29 October 2024, i.e. when the comet is more than about 0.87 au away from the Sun. In order to study the evolution of the Na emission in the coma of C/2023 A3, follow-up spectroscopy of the comet was scheduled with FLECHAS at the University Observatory Jena. On 3 November 2024, spectra of C/2023 A3 were taken with the instrument in its 2x2 binning mode (resolving power of R~7400) with a total integration time of 2 hours. For calibration, flatfield and arc lamp spectra were taken before observing the comet. The fiber of the spectrograph, which has a diameter of 3.9 arcsec in the sky, was guided on the center of the comets' coma to correct for the high proper motion of the comet. During the observations the comet was located at a heliocentric distance of about 0.98 au. The emission lines of [OI], NH2 and C2 were all detected again in the spectrum of C/2023 A3, while no Na emission was found. Only the absorption lines of Na were present in the spectrum, which originate from sunlight reflected by dust particles in the comet's coma.
Follow-Up Spectroscopy of Comet C/2023 A3 - Online Data
