S. Nicholas Raines

Assistant Scientist

Department of Astronomy

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S.N. Raines
211 Bryant Space Science Center
Dept. of Astronommy
University of Florida
Gainesville, FL 32611-2055, USA
phone: (352) 392-2052, ext. 244
raines at astro.ufl.edu

left: slicer mirrors, middle: ifu assembly, right: spectral line image

Florida Image Slicer for Infrared Cosmology and Astrophysics

FISICA is a fully cryogenic (i.e. operating at a temperature of 77.2K) all–reflective image–slicing integral field unit (IFU) for use with the FLAMINGOS near–infrared spectrograph. Designed to accept input beams near f/15, it provides 22 R(λ/(δλ)∼1300 spectra over a 16×33 arcsecond field of view.

The image slicing and re-arrangement into a virtual long–slit is accomplished with three monolithic powered mirror arrays. The three–part image above shows the image slicer at the left. Each of the 22 parallel long slender facets is a powered mirror, all tilted at different angles. The middle image shows the assembled IFU; the slicer array is the small gold-colored metal piece at the top of the image. The right image is a spectral line image of the dwarf starburst galaxy NGC 1569 (see Clark et al. 2006, in Journals); red is coded to Paschen β, green is H–band continuum, and blue is Helium–I (1.083 μm). The bright white clumps coincide with the location of massive super star clusters (SSCs) in NGC 1569. He I is indicative of stellar winds in high–mass stars, and its extended emission surrounding suggests avid star formation outside of the massive clusters. This result was unknown prior to these observations, and shows the power of integral field spectroscopy.

FISICA was designed by Prof. Steve Eikenberry (UF principal investigator, or PI), along with co-PI Prof. Glenn Boreman (University of Central Florida CREOL), and UF co-investigators Professors Richard Elston and Rafael Guzmán. Paul Glenn and Greg Hull-Allen at Bauer Associates assembled and aligned the optical train. Jeff Hoffmann, Michael Rodgers, and Kevin Thompson at Optical Research Associates worked extensively with Steve on the optical design and tolerancing. Scott Flint, Lovell Comstock, and Bruce Myrick at Corning NetOptix used their state-of-the-art diamond turning facilities to fabricate the mirror arrays. Jeff Julian at UF designed the mechanical fixturing to adapt the FLAMINGOS fore-Dewar to accept the FISICA IFU. Nicolas Gruel wrote all of the Python observation software used at the telescope for rapid target acquisition.

During the spring and summer of 2004 I worked with Steve on the lab integration and acceptance testing of the IFU into the FLAMINGOS fore–Dewar. For our warm lab tests this included setting up a light source with an f/15 beam and an SBIG CCD camera system focussed at the design focal plane. We then adjusted the mounting of the IFU until its virtual slitets matched the design focal plane and produced good images on the CCD camera. We later devised other cryogenic tests of the IFU, without the FLAMINGOS spectrograph. During this time I also wired the Dewar with temperature sensors and a warm–up heater loop, both to match the pre–existing connections on FLAMINGOS.

Integration of the FISICA fore–Dewar with the FLAMINGOS spectrograph was done in Tucson by Nicolas and me in the summer of 2004, at the NOAO lab facilities. The principal concern during these first tests was to verify the virtual slitlet from the IFU was indeed in focus with the spectrograph.

I worked closely with Jeff Julian and the KPNO staff to ensure a seamless installation at the KPNO Mayall 4–m telescope. Our First–Light observation run was in October 2004. Steve, Nicolas, Dave Clark, Rafael Guzmán and I devised and executed a number of observation strategy tests during this run, including methods to acquire targets, focus the telescope through the IFU, and how to efficiently dither the telescope during observations. A number of science performance observations included bright G stars, emission line stars and a planetary nebula. During this run we obtained new science observations of NGC 1569 described above in the text and in the image at the head of the page.

During the October 2004 observing run we determined that the IFU was insufficiently cold, leading to excess, unwanted, emission in the 2.2μm K–band. Steve and I devised a new set of thermal conduction straps between the IFU and the thermal bath in the Dewar, and I tested them in the spring of 2005. We had another observing run with FISICA in the summer of 2005.

From 2004 through fall 2009 FISICA was a visitor–class instrument at KPNO, available via collaboration with Prof. Eikenberry. In 2010 the FISICA IFU ws removed from the FLAMINGOS fore-Dewar. It is now on long–term loan to Prof. Dae-Sik Moon (University of Toronto). He and his team are designing WIFIS, the Wide Integral–Field Infrared Spectrograph, which will incorporate the FISICA IFU into its design.

Support for the FISICA project was provided by the University of Florida, the University of Central Florida, the Florida Space Research Initiative, and the Fundación por la Preservación del PSF.