CFHT, Instruments, Spectroscopy, ESPaDOnS

ESPaDOnS: an Echelle SpectroPolarimetric Device
for the Observation of Stars at CFHT


A Franco-Canadian project

managed by
Jean-François Donati,
Claude Catala and
John Landstreet

News
Classical Observing with ESPaDOnS ESPaDOnS in Queued Service Observing Mode
Characteristics and Performances Other relevant documents


ESPaDOnS is a bench-mounted high-resolution echelle spectrograph and spectropolarimeter
which was designed to obtain a complete optical spectrum (from 370 to 1,050 nm)
in a single exposure
with a resolving power of about 68,000 (in spectropolarimetric and 'object+sky' spectroscopic mode)
and up to 81,000 (in 'object only' spectroscopic mode).

Latest news (Updated Aug 13, 2008)
  1. ESPaDOnS IN QSO MODE
    Since Semester 2008A, ESPaDOnS is offered in Queued Service Observing only. PIs who want to submit Proposals should consult the ESPaDOnS in QSO Mode web page.

    Classical Observers (Semesters up to and including 2007B) can consult the ESPaDOnS in Classical Mode webpage.

  2. CROSS-TALK
    Thanks to the new triplet, installed in June 2006, the cross-talk has now decreased to 2-3% (linear to circular, and vice-versa). A new triplet (new design and new materials) has been ordered and will be received in the Fall of 2008.

    The triplet lens, located in the polarimeter between the aperture hole mirror and the rhombs, exhibits stress birefringence in the cold and induces the cross-talk.

    The lens used between June 18 2005 and February 2006 (replacement #1) showed birefringence, with about 7% of Stokes V (circular polarization) ending up in Stokes Q and Stokes U. The cross-talk produces spurious continuum polarization, which does not affect most programs because ESPaDOnS is best used to measure polarization in lines and not in the continuum (measurement of continuum polarization with ESPaDOnS is very difficult as the instrument was not designed to do that).

    Please see the ESPaDOnS known technical issues page for more details.

  3. EFFICIENCY / THROUGHPUT
    Thanks to the new fibers and connectors intalled in June 2006, the efficiency of ESPaDOnS has increased, and the flux is higher. The throughput is now at the best level we have ever seen (the level of the commissioning period of late 2004).

    The drop of efficiency was roughly 1.0mag for the period Jan-June 2005 total (with respect to the inital and best throughput values measured on the sky). Between June 2005 and February 2006, the spare spare fiber bundle has exhibiting a 0.4mag loss of flux (again with respect to the best throughput measured on the sky).

    Please see the ESPaDOnS known technical issues page for more details.

  4. DATA REDUCTION WITH LIBRE-ESPRIT

    Please note the following:

    BEFORE July 2005
    (with the script real_time_esprit)    		 invert the sign of V and Q
    the sign for U is OK
    AFTER July 2005
    (with the script libre_esprit)    		 invert the sign of U
    the signs for V and Q are OK


  5. CONTINUUM POLARIZATION

    Contemplating continuum polarization? Please consult the FAQ before you make any proposal. ESPaDOnS was not designed to do continuum polarization very well. See details on the Continuum Polarization page.

  6. If you have any question or concern, please contact the Support Astronomer Nadine Manset (manset -=at=- cfht.hawaii.edu).
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Characteristics and Performances [top]

The engineering that took place in September 2004 was very successful. A brief summary includes a few figures and graphs. In November and December 2004, commissioning took place, with average weather conditions.

For official information and numbers, please see the official ESPaDOnS webpage. The most recent update was in November 2006.

However, if that page is temporarily unavailable, you may use CFHT's copy of it (June 20, 2006 version). Some of the content is however unavailable on this copy (the Exposure Time Calculator for one).
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Other relevant documents [top]
  1. Photos
    1. ESPaDOnS arriving at the summit (July 2004)
    2. ESPaDOnS at CFHT (August 2004)
  2. Documents
    1. Development Responsibilities List
  3. Various presentations made at CFHT (newest first)
    1. Board of Directors, December 2004 [HTML, best with IE]
    2. Science Advisory Committee, November 2004, [PDF file | HTML, best with IE]
    3. Board of Directors, December 2003 [JPG slides]
    4. Science Advisory Committee, November 2003 [JPG slides]
    5. Science Advisory Committee, November 2002 [JPG slides]
    6. Science Advisory Committee, November 2001 [Gif and PS slides]
    7. Board of Directors, December 2000 [Gif and PS slides]
  4. Posters
    1. CASCA 2006 [PDF]
    2. CFHT Users' Meeting 2007 [PDF]
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http://www.cfht.hawaii.edu/Instruments/Spectroscopy/Espadons/
This CFHT Web page is maintained by Nadine Manset (manset -=AT=- cfht.hawaii.edu)