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We report precision atmospheric spectroscopy of $CO_2$ using a laser heterodyne radiometer (LHR) calibrated with an optical frequency comb. Using the comb-calibrated LHR, we record spectra of atmospheric $CO_2$ near 1572.33 nm with a…

Optics · Physics 2023-10-03 Ryan K. Cole , Connor Fredrick , Newton H. Nguyen , Scott A. Diddams

New observations of the quasar HE0515$-$4414 have been made using the HARPS spectrograph on the ESO 3.6m telescope, aided by the Laser Frequency Comb (LFC). We present three important advances for $\alpha$ measurements in quasar absorption…

Cosmology and Nongalactic Astrophysics · Physics 2021-03-08 Dinko Milaković , Chung-Chi Lee , Robert F. Carswell , John K. Webb , Paolo Molaro , Luca Pasquini

The LOw Frequency ARray (LOFAR) is a next-generation radio telescope which uses thousands of stationary dipoles to observe celestial phenomena. These dipoles are grouped in various 'stations' which are centred on the Netherlands with…

Solar and Stellar Astrophysics · Physics 2019-08-13 Richard A. Fallows , Ashish Asgekar , Mario M Bisi , Andrew R. Breen , Sander ter Veen

We perform heterodyne spectroscopy at 1.56 micron with a tunable laser and thermal radiation from the Sun. The laser tuning is calibrated with a frequency comb, providing a simple spectrometer with absolute frequency tracebility and…

Instrumentation and Methods for Astrophysics · Physics 2020-11-17 Connor Fredrick , Freja Olsen , Ryan Terrien , Suvrath Mahadevan , Franklyn Quinlan , Scott Diddams

(abridged) Even if the HARPS spectrograph has been operational for more than 15 years and it provides among the most precise Doppler measurements, improvements are still possible. One known problem, for instance, is the non-fully regular…

Earth and Planetary Astrophysics · Physics 2019-09-04 Adrien Coffinet , Christophe Lovis , Xavier Dumusque , Francesco Pepe

We report, for the first time, a multi-confocal Fluorescence Correlation Spectroscopy (mFCS) technique which allows parallel measurements at different locations, by combining a Spatial Light Modulator (SLM), with an Electron Multiplying-CCD…

We describe techniques for photometric calibration of optical spectra obtained with the MMT's fiber-fed spectrograph, Hectospec. The atmospheric dispersion compensation prisms built into the MMT's f/5 wide field corrector effectively…

The H{\alpha} line is an important optical line in solar observations containing the information from the photosphere to the chromosphere. To study the mechanisms of solar eruptions and the plasma dynamics in the lower atmosphere, the…

The possibility of an Earth-Sun analog beyond our solar system is one of the most longstanding questions in science. At present, answering this question embodies an extremely difficult measurement problem that requires multiple coordinated…

Knowledge of the spectrograph's instrumental profile (IP) provides important information needed for wavelength calibration and for the use in scientific analyses. This work develops new methods for IP reconstruction in high resolution…

Instrumentation and Methods for Astrophysics · Physics 2024-02-07 Dinko Milaković , Prashin Jethwa

Optical frequency combs have the potential to improve the precision of the radial velocity measurement of celestial bodies, leading to breakthroughs in such fields as exoplanet exploration. For these purposes, the comb must have a broad…

Instrumentation and Methods for Astrophysics · Physics 2023-06-06 Keisuke Nakamura , Ken Kashiwagi , Sho Okubo , Hajime Inaba

Spectral shaping is critical to many fields of science. In astronomy for example, the detection of exoplanets via the Doppler effect hinges on the ability to calibrate a high resolution spectrograph. Laser frequency combs can be used for…

We introduce a novel laser-scanning optical microscopy technique that employs optical-frequency-comb (OFC) lasers. This method facilitates multimodal spectroscopic imaging by analyzing interferograms produced via a dual-comb spectroscopic…

Optical spectrometers are widely used in scientific and industrial applications, and precise frequency calibration is essential for ensuring their reliable performance. Traditionally, spectrometers have been calibrated using reference gas…

We describe a successful effort to produce a laser comb around 1.55 $\mu$m in the astronomical H band using a method based on a line-referenced, electro-optical-modulation frequency comb. We discuss the experimental setup, laboratory…

Instrumentation and Methods for Astrophysics · Physics 2016-06-08 X. Yi , K. Vahala , S. Diddams , G. Ycas , P. Plavchan , S. Leifer , J. Sandhu , G. Vasisht , P. Chen , P. Gao , J. Gagne , E. Furlan , M. Bottom , E. Martin , M. Fitzgerald , G. Doppmann , C. Beichman

The LOw-Frequency ARray (LOFAR) is used to make precise measurements of radio emission from extensive air showers, yielding information about the primary cosmic ray. Interpreting the measured data requires an absolute and…

Astrocombs are ideal spectrograph calibrators whose limiting precision can be derived using a second, independent, astrocomb system. We therefore analyse data from two astrocombs (one 18 GHz and one 25 GHz) used simultaneously on the HARPS…

Instrumentation and Methods for Astrophysics · Physics 2020-02-19 Dinko Milaković , Luca Pasquini , John K Webb , Gaspare Lo Curto

Sky models have been used in the past to calibrate individual low radio frequency telescopes. Here we generalize this approach from a single antenna to a two element interferometer and formulate the problem in a manner to allow us to…

Instrumentation and Methods for Astrophysics · Physics 2017-06-28 Divya Oberoi , Rohit Sharma , Alan E. E. Rogers

The solar limb darkening function is well known and is widely employed in models of the solar atmosphere. However, there has been a lack of systematic spectrally resolved measurements. Therefore we recently decided to start an observing…

Solar and Stellar Astrophysics · Physics 2017-08-11 R. Ramelli , M. Setzer , M. Engelhard , M. Bianda , F. Paglia , J. O. Stenflo , G. Küveler , R. Plewe

Tunable lasers, with the ability to continuously adjust their emission wavelengths, have found widespread applications across various fields such as biomedical imaging, coherent ranging, optical communications and spectroscopy. In these…

Optics · Physics 2024-03-22 Baoqi Shi , Yi-Han Luo , Wei Sun , Yue Hu , Jinbao Long , Xue Bai , Anting Wang , Junqiu Liu