Early this month, we had our first commissioning run of the Folded Port Infrared Echellette, or FIRE, a near-infrared spectrograph designed for the Magellan Telescopes.  After a two-week installation period in late February/early March led by the instrument PI Rob Simcoe, FIRE team members John Bochanski and Matt Smith from MIT and Craig McMurtry from U. Rochester, and Magellan engineers (I missed all the action, teaching 250 students Physics 1), FIRE was ready to view the sky for a week-long commissioning run starting March 28th.

Early results have been spectacular.  A few of the image frames from the first week are shown below.  The high quantum efficiency and low readnoise of the Teledyne Hawaii 2RG detectors, and the excellent image quality of the Baade Telescope, has resulted in higher sensitivity than originally planned.   In the echelle mode, Rob has estimated roughly 20-25% efficiency, including telescope and slit losses, and a nearly-flat zero point of 16-17 AB magnitudes (1 count/sec/pixel) across the 0.85-2.4 micron range.  In plain language, this means we can observe very faint sources – such as a the coldest brown dwarfs and highest redshift quasars – with the echelle mode’s moderate resolution (λ/Δλ ≈ 6000).  The prism-dispersed mode has also proven very sensitive, and we’ve been able to follow-up several J ≈ 19-20 cold brown dwarf candidates from WISE with relative ease.  Look for first science results in the literature soon!

An A0 V "telluric standard" observed with FIRE's echelle mode. The 21 orders span a wavelength range of 0.85 to 2.4 micron from bottom to top. This image is a pairwise subtraction of two 10 s exposures, hence the postive and negative traces.

An unprocessed, 600-second exposure of the late T-type brown dwarf 2MASS 1217-0311 (J = 16) in FIRE's echelle mode. The star's light appears as occasional horizontal streaks in the various orders; the short vertical streaks are emission lines from OH in the Earth's atmosphere. The bright region at top is thermal emission (mostly from Magellan's "warm" mirrors) in the 2-2.5 micron region.

A high-redshift (z=6), J = 20 quasar observed with FIRE's echelle mode. FIRE is sufficiently sensitive to pick up continuum light from this ancient source, enabling studies of the gas along its line of sight. This is a pairwise subtraction of 2 900-second exposures.

Prism-dispersed mode of FIRE of the J = 16.7 T dwarf Ross 458C. This mode gives a lower resolution of 250, but high throughput. This image is a pairwise subtraction of two 150-second exposures, and the wavelengths go from 0.8 micon at the bottom to 2.5 micron at the top.

Acquisition image from FIRE's slit-viewing camera, which has a Mauna Kea J-band filter. The target (left of center) is in the slit, so appears to be split in half. This is a pairwise subtraction of two 5-second exposures.

Fully processed spectra of three cold brown dwarfs, obtained with FIRE's prism-dispersed mode, ranging from J=17 to 18. These data will be published in Burgasser et al. (2010, in preparation)

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