The Magellan f/15 Secondary Science Case. Laird Close Victor Gasho MIRAC4 team (Steward Observatory). Why A New Secondary For Magellan. The current f/11 has high (~15\%?) emissivity – same as ~5m scope with lower emissivity This cannot complete with Gemini redwards 2.3 um
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Predicted system performance at 10μm (left, Phase I – funded by NSF MRI) and 2.2μm (right, Phase II – not funded by MRI). Seeing of 0.73" at V, a wind of 6 m/s, 21 mag/sq arcsec sky brightness, and a sensor with readnoise of 2 electrons sampled at 330 Hz have been assumed in these simulations (our Andor gain CCD should have 1e RON and 500 Hz rates).
Note that tip-tilt alone is adequate for diffraction-limited imaging at Magellan at >8 microns. We should have nearly full sky coverage with the Andor tip-tilt/speckle camera as the fast guider.
(NOTE: images from the MegaMIR proposal – MIRAC4 has a 49.4” FOV with the f/15 secondary that samples l>11.9 microns
- size of Mirca4 field with a future MegaMIR 1k chip ~82”)
MIRAC4 50” FOV
MIRAC4 50” FOV
GLIMPSE - the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire - is a fully sampled, confusion limited, 4-band near- to mid-infrared survey of the inner two-thirds of the Galactic disk with a spatial resolution of ~2". The Infrared Array Camera (IRAC) imaged 220 square degrees at wavelengths centered on 3.6, 4.5, 5.8, and 8.0 microns in the Galactic longitude range 10 deg to 65 deg on both sides of the Galactic center and in Galactic latitude +/- 1 deg.
The area covered by GLIMPSE contains most of the star formation activity in the Galaxy and ~70% of the molecular gas in the Galaxy. The inner cutoff at |l| = 10 deg permits adequate sampling of both ends of the purported ~3 kpc central bar and possibly some of the nuclear bulge stellar population. They expect to determine the asymmetry of the bar (brighter at l>0 deg) with high accuracy. The outer cutoff at |l| = 65 deg includes all of the 5 kpc molecular ring, the Sagittarius spiral arm tangent, and the Norma spiral arm tangent. The Galactic center region is not included because of its extreme background brightness and high confusion limits. These confusion-limited areas in the center could be uniquely well probed by MIRAC4 @ f/15.
Newly discovered Extragalactic regions are also prime targets for study.
MIRAC4 50” FOV
1024x1024 arrays (like the MegaMIR Chip) will require very large chops (~82”) to utilize these new chips. No large telescope has >+/-10” chop. Our proposed secondary would be the largest chopping 10 um facility on a large telescope.
T-ReCS will likely not make the required 16 night semester minimum. NICI alone will use ~30% of the bright time, and FLAMINGOS-2 and GSAOI with MCAO will use up the rest of the bright time. Hence T-ReCS will likely not be used from 2008 onwards.
Magellan Mid-IR could be the leading (only?) US southern Mid-IR facility from 2008 on. And with its 82” FOV and 90” chopper the only large telescope location for the MegaMIR chips.