1. March 22, 2010Science with the William Herschel Telescope 2010-2022 H-band multi-object spectroscopy around the Galaxy Carlos Allende Prieto (IAC) and the APOGEE Team

2. March 22, 2010Science with the William Herschel Telescope 2010-2022 APOGEE A high-resolution (R~30,000) high-S/N H-band spectroscopic survey of 100,000 stars in the Galaxy Why high-resolution? Why in the H-band? Why now?

3. March 22, 2010Science with the William Herschel Telescope 2010-2022 Rationale Red giants/red clump have strong NIR flux. Complete point source sky catalogue to H ~ 13.5 available from 2MASS A H / A V = 0.17 (x 100 in flux at A V ~6) Access to dust-obscured galaxy Velocities to <1 km/s accuracy and precision abundances (15 elements) for giants across the Galaxy Low atmospheric extinction makes bulge declinations accessible from North (though over smaller field) Avoids thermal background problems of even longer

4. March 22, 2010Science with the William Herschel Telescope 2010-2022 APOGEE Science Case In the context of Galaxy structure and evolution: sampling the distribution functions (x, v, Z) of the Milky Way avoiding the biases of working at visible wavelengths In a broader context: does the Milky Way fit in a  -CDM universe?

5. March 22, 2010Science with the William Herschel Telescope 2010-2022 Terra incognita Local thin disk well studied (Geneva- Copenhagen, S4N, Fuhrmann papers …) Local and more distant halo well studied (SDSS) Local thick-disk well-studied (just recently) Not the case for the bulge (only Baade’s window explored) or distant parts of the Galactic disk

6. March 22, 2010Science with the William Herschel Telescope 2010-2022 Specific objectives Disk/Rotation Curve Surveys of stellar disk dynamics outside solar vicinity typically <~100 stars HI tangent point analyses assume circular rotation insensitive to non-axisymmetric effects (e.g., arms) and inoperable outside solar circle [V(>R sun ) poorly known]s I Gradients/lack of gradients in the thin/thick disks o Gas/stars in the spiral arms Galactic Bar Little current data, but possibly wide-ranging influence. Radial motions affect gas-mixing, metallicity gradients Bulge Poorly known. Connection of velocities and chemistry provide s strong constraints on inflow of material into bulgear Halo Internal dynamics of substructure. Inner/outer halo dichotomy

7. March 22, 2010Science with the William Herschel Telescope 2010-2022 What makes APOGEE’s spectrograph unique? We know: Phoenix (KPNO 2.1m,4.1m, CTIO 4m, Gemini South), NIRSPEC (Keck), CRIRES (VLT) We heard of NAHUAL (GTC), CARMENES (3.5m CAHA) R range detector Phoenix50,000-80,000 1-5  m 0.5x1 K CRIRES<100,000 0.95-5.2 4x0.5x1K NIRSPEC25,000 (2,000) 0.95-5.5 1x1 K

8. March 22, 2010Science with the William Herschel Telescope 2010-2022 What makes APOGEE’s spectrograph unique? Focused in the H band Larger detectors Grating (VPH vs. echelle): spectral coverage, efficiency Multi-object (300 fibers) APOGEE 30,000 1.5-1.7 3x 2x2 K Phoenix50,000-80,000 1-5 0.5x1 K CRIRES<100,000 0.95-5.2 4x0.5x1K NIRSPEC25,000 (2,000) 0.95-5.5 1x1 K

9. March 22, 2010Science with the William Herschel Telescope 2010-2022 Hardware Overview Camera VPH grating Fibers in & LN-2 autofill Collimator Fold 2 (dichroic) Fold 1 Detector Assembly (mounts to Camera) Fiber Racetrack Slithead (fiber “launch”)

10. March 22, 2010Science with the William Herschel Telescope 2010-2022 Hardware overview (Univ. of Virginia) Fibers (high-transmission low frd): 40 m H- band optimized (65% throughput). Prototypes near top expectations in hand Design includes a dichroic (cutting out thermal IR) Thanks to Fred Hearty for passing all the info!

11. March 22, 2010Science with the William Herschel Telescope 2010-2022 Collimator

12. March 22, 2010Science with the William Herschel Telescope 2010-2022 VPH Size matters. Design calls for a 50x30 cm grating! 3 recorded panels on a single gelatin substrate, sandwiched by two 2.5-cm layers. Several prototypes have demonstrated feasibility (should be done in April)

13. March 22, 2010Science with the William Herschel Telescope 2010-2022 Volume Phase Holographic (VPH) Grating

14. March 22, 2010Science with the William Herschel Telescope 2010-2022 Camera All lenses built and coated assembly to begin in two weeks 3 Teledyne 2048x2048 detectors (same as for JWST) QE~85% (dithering capabilities!)

15. March 22, 2010Science with the William Herschel Telescope 2010-2022 Camera

16. March 22, 2010Science with the William Herschel Telescope 2010-2022 Camera

17. March 22, 2010Science with the William Herschel Telescope 2010-2022 Cryostat All spectrograph cooled to 80 K in vacuum No entrance window Cryostat is 2.5x1.5x1.5m Vibration isolated with common commercial solutions (>99% removed at >10 Hz) Active thermal control (~1e-3 K) Multiple calib. Sources (ThAr, U, laser comb) Cryostat had 1st vacuum test, ready for 1st cold test. Delivery should happen in April

18. March 22, 2010Science with the William Herschel Telescope 2010-2022

19. March 22, 2010Science with the William Herschel Telescope 2010-2022

20. March 22, 2010Science with the William Herschel Telescope 2010-2022

21. March 22, 2010Science with the William Herschel Telescope 2010-2022 Deliveries A rich window sampling 15+ Elements (including C,N,O) R~30,000 provides <<1 km/s velocity errors (probably much much smaller, but stellar jitter) Fully automated reduction + analysis pipeline 300 fibers on, 1e5 stars using bright time 3 yrs on ARC 2.5m

22. March 22, 2010Science with the William Herschel Telescope 2010-2022 WHT An APOGEE-like spectrograph on WHT would be a different instrument: smaller field, different science (e.g. clusters, extra-galactic red giants, integrated extragalactic globular clusters) APOGEE, the spectrograph, costs is estimated at ~ 7 M$ (but much cheaper to repeat!) Concept fully proven Pipeline/acquis. Software can be recycled IAC is negotiating full participation in SDSS-III (i.e. in APOGEE)

23. March 22, 2010Science with the William Herschel Telescope 2010-2022 Another interesting example … VIRUS on the HET