Commissioning the polarimetric modes of the Robert Stobie spectrograph on the Southern African Large Telescope

S. B. Potter; Ken Nordsieck; Encarni Romero-Colmenero; Steve Crawford; Petri Vaisanen; Éric Depagne; David Buckley; Anthony Koeslag; Janus Brink; Christian Hetlage; Keith Browne; Lisa Crause; Alan Schier; James Allington

doi:10.1117/12.2232391

9 August 2016 Commissioning the polarimetric modes of the Robert Stobie spectrograph on the Southern African Large Telescope

S. B. Potter, Ken Nordsieck, Encarni Romero-Colmenero, Steve Crawford, Petri Vaisanen, Éric Depagne, David Buckley, Anthony Koeslag, Janus Brink, Christian Hetlage, Keith Browne, Lisa Crause, Alan Schier, James Allington

Author Affiliations +

Proceedings Volume 9908, Ground-based and Airborne Instrumentation for Astronomy VI; 99082K (2016) https://doi.org/10.1117/12.2232391
Event: SPIE Astronomical Telescopes + Instrumentation, 2016, Edinburgh, United Kingdom

Abstract

The Robert Stobie Spectrograph is currently the main workhorse spectroscopic instrument on the Southern African Large Telescope (SALT), which has been undergoing regular scientific operations since 2011. The visible beam of the RSS was designed to perform polarimetry in all of its modes, imaging and grating spectroscopy (with Multi Object Spectroscopy capability) from 3200 to 9000 Å. The polarimetric field of view is 4×8 arcmin. Initial early commissioning of the polarimetric modes was stalled in 2011 because a coupling fluid leak developed in the polarizing beamsplitter after less than a year of operation. As a result, it was decided to redesign the beamsplitter to use a different optical couplant. This was complicated by the unusual thermal expansion properties of the calcite optic, and by the necessity of aligning the individual elements in the beamsplitter mosaic (RSS is the first instrument to use a mosaic beamsplitter). Laboratory work selected a new couplant: a gel, Nye 451. Testing was completed with satisfactory results on a "sacrificial" calcite prism with the same geometry as an actual mosaic element. A successful assembly was performed and the beamsplitter was re-installed in SALT in mid-2015. We describe results from the renewed commissioning efforts to characterize polarimetry from SALT and include some early performance verification science.

Citation Download Citation

S. B. Potter, Ken Nordsieck, Encarni Romero-Colmenero, Steve Crawford, Petri Vaisanen, Éric Depagne, David Buckley, Anthony Koeslag, Janus Brink, Christian Hetlage, Keith Browne, Lisa Crause, Alan Schier, and James Allington "Commissioning the polarimetric modes of the Robert Stobie spectrograph on the Southern African Large Telescope", Proc. SPIE 9908, Ground-based and Airborne Instrumentation for Astronomy VI, 99082K (9 August 2016); https://doi.org/10.1117/12.2232391

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