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Michigan/MIKE Fiber System (MMFS) – Update Apr 2005

Michigan/MIKE Fiber System (MMFS) – Update Apr 2005. On Telescope: 27 science nights since start 2004A 2 dedicated engineering nights Installation: Process now well documented; takes 3-4 hrs plus overheads (MMFS to MIKE tricky in 1 day)

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Michigan/MIKE Fiber System (MMFS) – Update Apr 2005

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  1. Michigan/MIKE Fiber System (MMFS) – Update Apr 2005

  2. On Telescope: 27 science nights since start 2004A 2 dedicated engineering nights Installation: Process now well documented; takes 3-4 hrs plus overheads (MMFS to MIKE tricky in 1 day) -- Remove MIKE/guider/baffles on Clay -- Install MMFS -- Remove MIKE optics/rotate CCDs on MIKE -- Replace MIKE on platform -- Install MMFS fiber shoes into MIKE -- Prepare for observing (blocking filter, grating tilts, etc.) -- Focus, calibration, data, observe Still require a full web-based documentation of process.

  3. Issues -- Fiber tips still fail about 1 per night; easy to repair. -- Blue CCD developed high dark counts starting in Oct 2004 (acceptable), through Dec/Jan 2004/05 (unacceptable, loss of nights), Feb 2005 (even worse one lost night). -- High dark with odd, quasi-concentric pattern -- Visible pattern of contamination on CCD with same pattern. -- IT suggested O2 + heat flood; this solved the problem.

  4. 2400 sec image Dark rate ~ 0.5 e/sec/pix

  5. -- Very few spare fibers; more needed. -- More blocking filters to isolate more individual orders (Ca IR triplet; H-alpha; Mg complex) -- Arc control system was flaky (inconsistent operating voltage on HV lamps). New system installed based on MOE controller/GUI and MMFS lamp support system on the secondary.

  6. Operations Efficiencies: For dSph kinematic studies we can compare. [1-2 km/s to V=20.5-21.0 red giants] VLT – 10 stars per hr (+ high res spectra) MMT – 8 stars per hr (based on recent run; some light leak problems that should be fixed soon). MMFS – 25 stars per hour Includes all overheads, standards, etc. Explicit overheads: 20-45 min for fiber changes 5 min per velocity of abund standard 2 min per arc

  7. MMFS: Data • Sculptor red • giants • 5130-5190 A • (Mg complex) • V = 20.5-19.0 • ET = 2.5 hours

  8. Samples are substantially bigger: 1991, 1992, 1993, 1994, 2002

  9. And growing rapidly: 1991, 1992, 1993, 1994, 2002 3 hours in October 2004

  10. Velocity errors can be managed (14% repeat observations), even in faint, metal-poor stars. • Carina red giant • R ~ 18000 • V ~ 19.6 • CCF precision • ~ 1 km/s . . . The dispersion is sensitive to excess velocity errors only when these errors become large compared to the dSph’s overall dispersion . . . (Kleyna et al. 2005, regarding the history of Sextans velocity error estimates).

  11. MMFS/Hectochelle: dSph Status Report Galaxy Ntarg Nobs MV Sculptor 3200 1068 +0.5 Fornax 5000 560 -0.7 Carina 1600 1560 +0.0 Leo I 1500 -- -1.5 Sextans 2200 1190 +0.3 Draco 1200 -- +1.0 Total = 4300 different stars observed so far; 700 repeats. For comparison: 450 total in Mateo 1998 summary. Will hear more from WHT, VLT, Keck at this meeting . . .

  12. User concerns -- Learning curve for MMFS operations is steep. May require a `fiber operator’ who is employed only for MMFS runs and paid for by users as part of the cost of plates and plate fabrication. Need to coord- inate with LCO/Magellan staff. -- Plate fabrication requires good coordinates from users; all software for plate fabrication are operating and well-tested. -- Fiber assignment is still primitive; hope to improve this in anticipation of 2005B observations.

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