2. Nod & Shuffle at Magellan LCIR Survey Update October 18 2002 GDDS Preview

3. Conventional Slit Spectroscopy Sky subtraction is primary limitation –Slit irregularities –Flat-field errors –Residual Fringing –Geometric distortions –Low slit density on sky Beam switching ? –Variable sky spectrum –Read noise penalty –High read-out overhead The solution: ‘nod & shuffle’

4. Obscured Charge Storage Area Obscured Charge Storage Area First Exposure Active slit area

5. “A” position “B” position Now nod telescope and shuffle charge

6. Nod & shuffle the other way “A” position “B” position

7. Repeat N times and then readout

8. Difference of two positions

9. Finally shift and add both

10. LBL High Resistivity CCDs

11. No fringing, but high CR rates

12. LBL High Resistivity CCDs Straight average - 2 hours Nod & Shuffle

13. LBL High Resistivity CCDs +/- 200 DN rejection

14. Sky cancellation: ‘nod and shuffle’ Storage of ‘sky’ image next to object image via ‘charge shuffling’ Zero extra noise introduced, rapid switching (60s) A B ABAB Typically A=60s/15 cy: 1800s exposure  10  subtraction

15. Another example

16. GMOS N&S Sky residuals SUMMED along long slit (1.8 arcmin) Raw Sky/20 Subtracted sky (i.e. ~10  level is enough for 200,000 sec pointed obs.) Cycle: A=60s B=60s + 25s o/head

17. GMOS Nod&Shuffle Multislit

19. Maximum Slit Utilization

20. Nod & Shuffle on IMACS

21. 2’’ slits 2’’ gaps

22. Micro-Shuffling on IMACS 2” slits 2” gaps 4000A per spectrum

23. Micro-Shuffling on IMACS

24. Macro-Shuffling on IMACS High Slit Density or IFU mode

25. Macro-Shuffling on IMACS High Slit Density or IFU mode

26. Macro-Shuffling on IMACS High Slit Density or IFU mode

27. Technical and Practical Considerations Telescope, Guider and CCD controller must be well synchronized Active Optics must work with short dwell time Overheads must be minimized Mask making software needs special capabilities Reduction software ( done! - Abraham & Glazebrook) Order blocking filters?

28. Las Campanas IR Survey McCarthy, Persson, Martini, Koviak (OCIW) Chen (MIT), Marzke(SFSU), Carlberg, Abraham(UT) Ellis (Caltech) Evolved Galaxies at 1 < z < 2

29. Las Campanas IR Survey Goal: Empirical understanding of early galaxy evolution Target: 1 square degree to K = 21 Pilot survey in 2000/2001: VRIH to H=20.5 Six fields around the equator (2 in south!) 1 square degree in BVRIz’H 0.5 square degrees in J & K to K = 20.8 200+ redshifts with LDSS2 ~ 50 redshifts with GMOS & LRIS

30. Color-Magnitude Diagram Stars 0.0 < z < 1.0 1.0 < z < 1.5 1.5 < z < 2.0 500 sq. arcmin

31. Color-Color Diagrams Stars form distinct sequence Z > 1 galaxies appear at K ~ 19 Z > 1.5 galaxies at K > 20.5

32. Color-Color Diagrams Stars form distinct sequence Z < 1 galaxies well sampled at K ~ 19

33. Color-Color Diagrams Stars form distinct sequence Z > 1 galaxies appear at K ~ 19

34. Color-Color Diagrams Stars form distinct sequence Z > 1 galaxies appear at K ~ 19 Z > 1.5 galaxies at K > 20

35. Color-Color Diagrams Stars form distinct sequence Z > 1 galaxies appear at K ~ 19 Z > 1.5 galaxies at K > 20 Reddest galaxies follow minimal evolution track

36. Color-Redshift Diagrams

37. Photometric Redshifts from LCIR

39. Clustering of Red Galaxies

40. Evolving Luminosity Functions LFs derived from photo- z’s with modified likelihood approach LF at intermediate z agrees well with CNOC2 Very little apparent evolution in L* to z ~ 1.2

41. Gemini Deep Deep Survey GDDS Team: Karl Glazebrook (JHU), Bob Abraham (Toronto), Pat McCarthy (OCIW), Rick Murowinski (DAO), Ray Carlberg (Toronto), Ron Marzke (SDSU), Sandra Savaglio (JHU), H-W Chen (OCIW) David Crampton (DAO), Isobel Hook (Oxford), Inger Jørgensen & Kathy Roth (Gemini) Goal: Deep 100,000 sec MOS exposures on Las Campanas IR Survey fields to get redshifts of a complete K<22.4 I<25 sample covering 1<z<2

43. Goals: First Complete sample 1<z<2 –use photo-z’s to weed out low-z galaxies (BVRIzJHK) Determine luminosity and mass functions –Can we see the assembly of mass? –Massive galaxies at z=2 would severely trouble CDM –Mass(z) more robust than SFR(z) Relate to galaxy morphology (ACS) –Identify Ell/Sp/Irr over 1<z<2 –Track low-z behavior to high-z E.g. can we see mass assembly of giant Ellipticals? Can we track the dynamical evolution of spiral disks Track SFH over 1<z<2: –Age of galaxies, metallicities of population

44. GDDS history Sep 2001: start of GDDS evil planning Jan 2002: team approached Gemini observatory with nod & shuffle proposal Feb 2002, obtained Gemini go-ahead. Feb-May 2002. Implementation of N&S at DAO (~$10K cost) May 2002: first N&S engineering observations on 8m July 2002: N&S commissioned on sky Aug 2002: First 4 nights of GDDS  Science Verification for N&S  success!! Sep-Dec 2002: Band I queue time, 50 hrs

45. Gemini + GMOS GMOS spectrograph Gemini GMOS LRIS LDSS1 Tel.+instr. efficiency GMOS represents the best possible option for a red sensitive MOS. Ideal system for nod & shuffle

46. GDDS sample LCIRS 4 fields BVRIzJHK s 26  26 Limits: B<26.0 V<26.5 R<26.8 I<25.8 z<24.7 J<22.5 H<22.5 K s <22.4 Use photo-z’s to weed out z<0.7 foreground I<25 typical model n(z):

47. GDDS mask 84 objects  2 tiers with 150 l/mm grating

48. GDDS Spectra 77 objects 40,000 secs

49. GDDS Nod&Shuffle Mask

51. [OII] Redshifts from GDDS 23.7 < I(AB) < 24.2

52. I=23.8 Example object: raw object+sky OH forest

53. I=23.8 z=1.07 Example object: N&S subtracted [OII] 3727 at 7700Å

54. GDDS: Oct 2002 snapshot GDDS SV Aug 2002 + Band I Queue time (Sep/Oct 2002) Up to 100 ksec on first field (SA22) First 40 ksec now reduced and very preliminary redshifts TO COME 2002-2003 (total time awarded 50 hrs in Band I): Complete 3 GDDS fields, secure 100 z>1 redshifts

55. GDDS: ultra-super-preliminary results These are just the ‘easy’ ones so far! ~ 40 ksec Working on CCF Data on this field is still coming in. Full 100,000 secs will pound on z=1.5 old red galaxies

56. High Redshift Elliptical Galaxies? FeII MgII 53W091 at z=1.393 V  I=2.2 I  K=2.94 Model: 4 Gyr old stellar population at z=1.4, age of Universe = 4.5Gyr z(form) ≈10 Obj # 398 from GDDS SA22 V  I=1.7 I  K=2.7 Wavelength / Angstroms f Rest-frame UV absorption line redshifts!

57. Photometric Redshifts from LCIR

58. Colors of GDDS galaxies GDDS HDF LBGs (Papovich et al. 2001) z=1.4 E/S0 template z=1.4 Sbc template

59. Color-z of GDDS galaxies At least halfway across the desert!! Again just the easy ones…

60. GDDS: summary GDDS hits complete sample at z>1 –Photo-z selection z>1 ~works Gets spectra via ‘nod & shuffle’ sky cancellation –Successfully commissioned July-Aug 2002, have data on first (half) field Are we seeing a dearth of high mass galaxies at z>1 ? Possible epoch of mass assembly? TO COME 2002-2003: Complete 3 GDDS fields, secure 100 redshifts Apply for HST/ACS imaging for morphologies Mass function vs Morphology vs z.

61. GDDS: seeking old galaxies at z>1 z=1.4, I  K=2.7