arXiv subjects

Stephanie Monty

Publications and source records attributed to Stephanie Monty.

40 records · Page 3Linked to original sources

arXiv2018

MSE FiTS: the ultimate multi-fiber optic transmission system

The Maunakea Spectroscopic Explorer (MSE) is a next-generation observatory, designed to provide highly multiplexed, multi-object spectroscopy over a wide field of view. The observatory will consist of (1) a telescope with an 11.25 m aperture, (2) a 1.5 square-degree science field of view, (3) fibre optic positioning and transmission systems, and (4) a suite of low (R=3000), moderate (R=6000) and high resolution (R=40,000) spectrographs. The Fibre Transmission System (FiTS) consists of 4332 optical fibres, designed to transmit the light from the telescope prime focus to the dedicated spectrographs. The ambitious science goals of MSE require the Fibre Transmission System to deliver performance well beyond the current state of the art for multi-fibre systems, e.g., the sensitivity to observe magnitude 24 objects over a very broad wavelength range (0.37 - 1.8 microns) while achieving relative spectrophotometric accuracy of <3% and radial velocity precision of 20 km/s.

astro-ph.IM↗

arXiv2018

Automated testing of optical fibres: towards the design of the Maunakea Spectroscopic Explorer Fibre Transmission System

We present the results of an automated fibre optic test bench constructed at the University of Victoria as part of the Maunakea Spectroscopic Explorer (MSE) Fibre Transmission System (FiTS). In preparation for MSE-FiTS, we have begun characterizing the focal ratio degradation (FRD) of candidate multi-mode fibres with the ultimate goal of testing all ~4000 MSE fibres. To achieve this, we have built an optical bench to perform an automated version of the collimated beam test. Herein we present the design of the bench and discuss the automation of components by introducing the Big FiTS Fibre Wrapper (Big FFW), our open-source automation software. We conclude with the results of tests performed using the Big FFW on a sample of candidate fibre, comparing the Big FFW results against those found using manual methods. Our results suggest that the candidate MSE fibre meets the science requirement of < 5% FRD at f=2 and less than 1% disagreement between both measurement methods.

astro-ph.IM↗

arXiv2018

An Application of Deep Neural Networks in the Analysis of Stellar Spectra

Spectroscopic surveys require fast and efficient analysis methods to maximize their scientific impact. Here we apply a deep neural network architecture to analyze both SDSS-III APOGEE DR13 and synthetic stellar spectra. When our convolutional neural network model (StarNet) is trained on APOGEE spectra, we show that the stellar parameters (temperature, gravity, and metallicity) are determined with similar precision and accuracy as the APOGEE pipeline. StarNet can also predict stellar parameters when trained on synthetic data, with excellent precision and accuracy for both APOGEE data and synthetic data, over a wide range of signal-to-noise ratios. In addition, the statistical uncertainties in the stellar parameter determinations are comparable to the differences between the APOGEE pipeline results and those determined independently from optical spectra. We compare StarNet to other data-driven methods; for example, StarNet and the Cannon 2 show similar behaviour when trained with the same datasets, however StarNet performs poorly on small training sets like those used by the original Cannon. The influence of the spectral features on the stellar parameters is examined via partial derivatives of the StarNet model results with respect to the input spectra. While StarNet was developed using the APOGEE observed spectra and corresponding ASSET synthetic data, we suggest that this technique is applicable to other wavelength ranges and other spectral surveys.

astro-ph.IM↗

arXiv2016

The Outer Solar System Origins Survey: I. Design and First-Quarter Discoveries

We report the discovery, tracking and detection circumstances for 85 trans-Neptunian objects (TNOs) from the first 42 deg$^{2}$ of the Outer Solar System Origins Survey (OSSOS). This ongoing $r$-band Solar System survey uses the 0.9 deg$^{2}$ field-of-view MegaPrime camera on the 3.6 m Canada-France-Hawaii Telescope. Our orbital elements for these TNOs are precise to a fractional semi-major axis uncertainty $<0.1\%$. We achieve this precision in just two oppositions, as compared to the normal 3-5 oppositions, via a dense observing cadence and innovative astrometric technique. These discoveries are free of ephemeris bias, a first for large trans-Neptunian surveys. We also provide the necessary information to enable models of TNO orbital distributions to be tested against our TNO sample. We confirm the existence of a cold "kernel" of objects within the main cold classical Kuiper belt, and infer the existence of an extension of the "stirred" cold classical Kuiper belt to at least several AU beyond the 2:1 mean motion resonance with Neptune. We find that the population model of Petit et al. (2011) remains a plausible representation of the Kuiper belt. The full survey, to be completed in 2017, will provide an exquisitely characterized sample of important resonant TNO populations, ideal for testing models of giant planet migration during the early history of the Solar System.

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