The dirt in astronomy's genie lamp: ThO contamination of Th-Ar calibration lamps

Gillian Nave; Florian Kerber; Elizabeth A. Den Hartog; Gaspare Lo Curto

doi:10.1117/12.2312286

10 July 2018 The dirt in astronomy's genie lamp: ThO contamination of Th-Ar calibration lamps

Gillian Nave, Florian Kerber, Elizabeth A. Den Hartog, Gaspare Lo Curto

Proceedings Volume 10704, Observatory Operations: Strategies, Processes, and Systems VII; 1070407 (2018) https://doi.org/10.1117/12.2312286
Event: SPIE Astronomical Telescopes + Instrumentation, 2018, Austin, Texas, United States

Abstract

Thorium-Argon hollow cathode lamps are commonly used as wavelength calibration lamps for high-resolution astronomical spectrographs (e.g. the European Southern Observatory’s (ESO) High Accuracy Radial velocity Planet Searcher (HARPS) and Ultraviolet and Visual Echelle Spectrograph (UVES)). They have been instrumental in supporting high precision work such as the search for extra-solar planets using the radial-velocity method. However, several years ago astronomers found that the quality of commercial Th-Ar lamps had deteriorated, when new lamps showed a “forest” of lines at low intensity levels obscuring faint atomic thorium lines rendering them useless for wavelength calibration in some regions. Based on information provided by the manufacturers the presence of molecular emission from thorium oxides has been suspected as the likely cause of this problem. We have now conclusively identified the observed emission bands as being due to strong molecular bands of ThO, confirming the source of the contamination of the hollow cathode lamps.

We have recorded spectra of new Th-Ar lamps showing contamination using the high-resolution echelle spectrograph at the University of Wisconsin and ESO’s new Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) spectrograph in order to determine the positions of the ThO lines. We shall present our initial analyses of these spectra, describing the wavelength regions most affected, their dependence on the lamp current, and measurements of the ThO line positions.

Conference Presentation

Citation Download Citation

Gillian Nave, Florian Kerber, Elizabeth A. Den Hartog, and Gaspare Lo Curto "The dirt in astronomy's genie lamp: ThO contamination of Th-Ar calibration lamps", Proc. SPIE 10704, Observatory Operations: Strategies, Processes, and Systems VII, 1070407 (10 July 2018); https://doi.org/10.1117/12.2312286

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available