Follow-Up Imaging and Spectroscopy of Comet C/2025 R2
ATel #17462; M. Mugrauer, K.-U. Michel, E. Loesch
on 29 Oct 2025; 20:01 UT
Credential Certification: Markus Mugrauer (markus@astro.uni-jena.de)
Referred to by ATel #: 17505
We have carried out follow-up spectroscopic observations of the central part of the coma of comet C/2025 R2 with the Échelle spectrograph FLECHAS, which is installed at the 90 cm telescope of the University Observatory Jena. The comet was observed on 18 October 2025 directly before comet C/2025 A6, whose observations were already reported in ATel#17456. The instrument was operated in its 2x2 binning mode (R~7400) and one spectrum with an integration time of 600 s could be taken. During the spectroscopy of the comet, the fiber of the spectrograph, which has a diameter of 3.9 arcsec in the sky, was centered on the coma of C/2025 R2, to which the telescope was guided to correct for the high angular motion of the comet. In the wavelength range between 5000 and 7500 Å the spectrum of C/2025 R2 shows many emission features the most prominent ones are those of C2, NH2, and [OI]. Due to the velocity of the comet relative to the observation site, the detected emission features are blueshifted (by about 4 km/s), which agrees well with the expected RV value based on the current orbital solution of the comet. In contrast to C/2025 A6 no Sodium emission was detected in the spectrum of the coma of C/2025 R2, which was at a heliocentric distance of 0.95 au, while C/2025 A6 was only 0.71 au from the Sun. In order to measure the apparent brightness of C/2025 R2, its position in the sky and to study its morphology, the comet was also imaged simultaneously to the spectroscopic observations in the B-, V-, and R-band with the CCD-camera CTK-II, which is operated at the 25 cm Cassegrain auxiliary telescope of the observatory.
Follow-Up Imaging and Spectroscopic Observations of Comet C/2025 R2 - Online Data
