Related papers: The Spectrum of C/2023 A3 Indicates A Depleted Com…

We present high spectral resolution optical observations of comet 21P/Giacobini-Zinner from six nights in 2018. The observations were obtained with the Tull coude spectrograph on the 2.7m Harlan J. Smith Telescope of McDonald Observatory.…

Comets are primitive remnants of the early Solar System whose composition offers fundamental clues to their formation and evolution. High-resolution, broad-wavelength spectroscopy is crucial for identifying volatile species and constraining…

We present the results of a molecular survey of long period comets C/2021 A1 (Leonard) and C/2022 E3 (ZTF). Comet C/2021 A1 was observed with the IRAM 30-m radio telescope in November-December 2021 before perihelion when it was closest to…

We present spectroscopy of the coma center of comet C/2020 F3 (NEOWISE), carried out at the end of July 2020 with the \'Echelle spectrograph FLECHAS at the University Observatory Jena. The comet was observed in 5 nights and many prominent…

Comet C/2006 W3 (Christensen) was observed in November 2009 at 3.3 AU from the Sun with Herschel. The PACS instrument acquired images of the dust coma in 70- and 160-micrometers filters, and spectra covering several H2O rotational lines.…

Comet C/2007 N3 (Lulin) was observed with the Japanese infrared satellite AKARI in the near-infrared at a post-perihelion heliocentric distance of 1.7 AU. Observations were performed with the spectroscopic (2.5--5.0 micron) and imaging…

We report spectra from 3000-5900 A for comet 96P/Machholz, obtained on 2007 Apr 27 UT with the 3-m Shane telescope at Lick Observatory. The spectra are extremely carbon poor, and show a prominent NH_2 series, but no CN emission. NH, NH_2,…

A lower-than-solar elemental nitrogen content has been demonstrated for several comets, including 1P/Halley and 67P/C-G with independent in situ measurements of volatile and refractory budgets. The recently discovered semi-refractory…

On 3 and 4 October, 1995, we obtained high spectral resolving power (R=\lambda/\Delta\lambda = 60,000) observations of comet 122P/de Vico using the 2DCoude cross-dispersed echelle spectrograph on the 2.7-m telescope of McDonald Observatory.…

The discovery of the first active interstellar object 2I/Borisov provides an unprecedented opportunity to study planetary formation processes in another planetary system. In particular, spectroscopic observations of 2I allow us to constrain…

We monitored the planet-bearing solar-type star HD209458 for sodium absorption in the region of the stellar NaI D1 line that would be indicative of cometary activity in the system. We observed the star using the HET HRS with high S/N and…

We have used the Spitzer Space Telescope Infrared Spectrograph (IRS) to observe the 5-37 micron thermal emission of comet 73P/Schwassmann-Wachmann 3 (SW3), components B and C. We obtained low spectral resolution (R ~ 100) data over the…

Spectral line survey observations are conducted toward the high-mass protostar candidate NGC 2264 CMM3 in the 4 mm, 3 mm, and 0.8 mm bands with the Nobeyama 45 m telescope and the Atacama Submillimeter Telescope Experiment (ASTE) 10 m…

We report on the detection of a narrow feature at 262816.73 MHz towards Orion and the cold prestellar core B1-bS, that we attribute to the 1(0)-0(0) line of the deuterated Ammonium ion, NH3D+. The observations were performed with the IRAM…

On July 1st 2025 the third interstellar object, 3I/ATLAS or C/2025 N1 (ATLAS), was discovered, with an eccentricity of $e=6.15 \pm 0.01$ and perihelion of $q=1.357\pm0.001$ au. We report our initial visible to near-infrared (420-1000 nm)…

We combine ground- and space-based observations of long-period comet C/2021 O3 (Panstarrs) (perihelion distance 0.287 au) in order to investigate its reported near-perihelion destruction. Pre-perihelion photometric observations show a…

Long-period comets are planetesimal remnants constraining the environment and volatiles of the protoplanetary disc. We report the discovery of hyperbolic long-period comet C/2022 E3 (ZTF), which has a perihelion $\sim$1.11 au, an…

The 2023 perihelion passage of comet C/2022 E3 (ZTF) afforded an opportunity to measure the abundances and spatial distributions of coma volatiles in an Oort cloud comet at high spatial resolution near its close approach to Earth…

We report optical imaging, optical and near-infrared polarimetry, and Spitzer mid-infrared spectroscopy of comet C/2007 N3 (Lulin). Polarimetric observations were obtained in R (0.676 micron) at phase angles from 0.44 degrees to 21 degrees…

Imaging polarimetry enables the spatially resolved investigation of cometary dust properties across different morphological structures. While cometary comae have been studied thoroughly in the pertinent literature, cometary tails have…