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FALL 2005 SDSS-II PROJECT SCIENTIST REPORT

FALL 2005 SDSS-II PROJECT SCIENTIST REPORT. Jim Gunn. SDSS sky coverage to date. Imaging. Spectroscopy. Toward SDSS-II: Where we are. 1. The DA system 2. Supernovae 3. SEGUE 4. Legacy 5. Calibration. The New DA System. FEATURES:

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FALL 2005 SDSS-II PROJECT SCIENTIST REPORT

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  1. FALL 2005 SDSS-II PROJECT SCIENTIST REPORT Jim Gunn

  2. SDSS sky coverage to date Imaging Spectroscopy

  3. Toward SDSS-II: Where we are 1. The DA system 2. Supernovae 3. SEGUE 4. Legacy 5. Calibration

  4. The New DA System FEATURES: 1. New Power-PC based VME single-board machines, one for each logical dewar—10 in all. Approximately 40x faster, much larger memory 2. New Linux host machine and file server, ~3TB of storage. Data now is transferred to the host as soon as it is taken and stored in a standard Linux file system where it can be accessed immediately for QA and diagnostics. 3. The data are transferred over the new microwave link to FNAL and thence to Princeton for processing and storage. We no longer use tapes. Backups are made on removable disks on the mountain.

  5. The New DA System : Status Installation work began in middle August. After a few bitten fingernails, We observed (!) with it in the early September run, and have been since. Small problems continue to be solved, but we have lost NO data to DA problems. The near-real time capability has already been used effectively to diagnose problems The computing folks at FNAL deserve many heartfelt kudos for the quick and excellent development, as do the observers for finding workarounds to the problems which have surfaced in real time.

  6. SDSS SN Science Goals • Obtain ~200 high-quality SNe in the `redshift desert’, z~0.05-0.35: continuous Hubble diagram • Probe Dark Energy in z regime arguably less sensitive to evolution than, and complementary to, deeper surveys • Study SN Ia systematics with high photometric accuracy • Search for additional parameters to reduce Ia dispersion • Determine SN/SF rates/properties vs. z, environment • Rest-frame u-band templates for z >1 surveys • Database of Type II and rare SN light-curves (large survey volume with multi-band coverage)

  7. SN Program: 2.5m Imaging • Repeat imaging of ~2.5ox120o deg. region along celestial equator (SDSS stripe 82) for three 3-month runs (Sep-Nov. 05-’07) • Alternate every other night between strips 82N and 82S, giving dense sampling, early detection, high-quality light-curves • Why stripe 82?  repeated imaging in SDSS I allows veto catalog of variables; more accurate photometry for calibration; deeper template from co-add  Use Fall months: complement Legacy, SEGUE programs Wide follow-up available from N and S hemispheres • Frame subtraction in SDSS gri allows SN Ia selection in <24 hrs

  8. Fall 2004: Early Science & Test Run • Imaging: 20 nights of SDSS 2.5m scheduled every other night late Sept.-mid Nov., covered half the survey area: ~1/2 the nights were useable. • Follow-up spectroscopy: ARC 3.5m, HET 9.2m • Follow-up imaging (during/after run): NMSU 1m, ARC 3.5m • Science Goal: ~10 well-measured SN Ia light-curves with confirmed spectroscopic types and redshifts. • Yield: 16 confirmed Ia’s: 0.05<z<0.32 with z = 0.15, 5 Type II, 1 luminous Type Ic; 8 confirmed Ia’s found before peak; +~10 more likely (spectroscopically unconfirmed) Ia’s • Engineering goals met: • Rapid processing and selection of candidates in g,r using prototype compute cluster on-mountain • Coordinated follow-up observations • Studied detection efficiency and photometric accuracy under varying conditions (including moon)

  9. SN2004ie SN Ia z=0.0513 3 epochs of ARC 3.5m spectroscopy

  10. Improvements for 2005 Run: • Development Highlights: Frame subtraction: improved diagnostics, remapping, masked pixels, PSF determination (from PHOTO), convolution, object finding, using co-added template images, added i band Database: improved veto & star catalogs `real-time’ efficiency tests with artificial SNe in data stream Multi-color SN target selection using multi-band light curve fitting with and without host photo-z or spectro-z: pre-typing Web interface for human scanning of SN candidates Public webserver for confirmed candidates  Hardware: 10 faster dual processors at APO: process gri in ~18 hrs • More extensive follow-up program • More experienced team w/ a few new faces

  11. SDSS II SN Follow-up 2005 • Spectroscopy: SN typing, redshift, (multi-epoch spectrophotometry for improved K-corrections & sub-typing) • NIR imaging: extinction/reddening and low-z light curves • Optical imaging: follow high-z light curves beyond SDSS limit • Spectroscopy:ARC 3.5m (31 half-nights), HET (>60 hrs), MDM 2.4m (~37 nights), Subaru (share 6 nights), WHT (6 nights), Supernova Factory (low-z targets); SALT proposed • NIR imaging: Carnegie Supernova Project (selected targets) • Optical imaging: NMSU 1m, MDM, UH 88in (6.5 nights), VATT (7 nights), WIYN (3 nights shared), INT (1 night), Liverpool Telescope (4 hours)

  12. z = 0.07, confirmed at WHT SN 2005 ff

  13. Very raw Hubble diagram for 50 Ia’s • Preliminary rough photometry, not corrected for extinction or brightness-decline relation, yet  = .25 mag! Curve is concordance cosmology, not a fit to the data.

  14. http://www-sdss.fnal.gov:8000/sdssdp/supernova-dp/sdsssn.htmlhttp://www-sdss.fnal.gov:8000/sdssdp/supernova-dp/sdsssn.html 2005 Run: Progress Report Sept. 1- Oct. 15 (half the ‘05 run):  38 nights were scheduled, data taken on 25 of those nights; over half of the strip area (60 deg in RA) was covered on 18 nights. Conditions range from `SDSS survey quality’ (photometric, dark, good seeing) to mixed clouds and moon.  On-mountain data processing has kept up, despite occasional glitches (brand new SDSS DA system; occasional crashes of new SN compute cluster). Rotating team of ~15 scanners have examined 88,363 objects that appeared in subtracted frames and had passed software cuts (which removed fast-moving asteroids, known stars, artifacts, etc), and found 14,749 of those potentially interesting --> 5324 distinct SN candidates which were run through light-curve fitting code to select spectroscopic targets. Results: 80 SN candidates targeted for spectroscopy, 52 spectroscopically confirmed SNe Ia (including 7 `probable’ Ia’s), a handful more unconfirmed but likely Ia’s, 2 confirmed type II, 1 confirmed luminous Ibc (hypernova); 4 CBET `circulars’ released; z-range: 0.05-0.37. Avg. of 6 SDSS observations per confirmed SN so far (+ other optical follow-up). Very high Ia efficiency.

  15. SEGUE Spatial structure, kinematics, chemical properties of the old stellar populations in the Galaxy: 1. The halo: velocity dispersion ~130 km/sec, density rough power law, roughly spherical, metal-poor. 2. The thick disk: velocity dispersion ~40km/sec, scale height ~1 kpc, intermediate metallicity, origin very uncertain 3. The old thin disk: velocity dispersion ~20km/sec, scale height ~200 pc, high metallcity. Chemical history, most metal-poor stars, streams and other merger remnants..... How was the Galaxy put together?

  16. SEGUE IMAGING, Galactic Coordinates ~4000 sq. deg.; Approximately 1/3 done, head start in 2004.

  17. SEGUE SPECTROSCOPY ~400 plates, 240,000 stars, head start in 2004, very little spectroscopic data yet this year. (Supernovae). Will begin in earnest in November, and share time with Legacy in the spring. plates are in a long-exposure/short-exposure pair. Spectroscopic Categories: White dwarfs: colors, 25 per plate pair Cool white dwarfs: color, proper motion, per plate pair BHB/A: colors, 150 per plate pair F turnoff, metal poor: colors, 150 per plate pair G main sequence: color range, sparse sample, 375 per pair K giants: color, proper motion M dwarf : regular, subdwarf, high velocity: colors and PM (50 per pp) AGB red candidates: color, 15 per plate pair

  18. SEGUE Spectroscopic targets in color space

  19. SEGUE Target Selection Status Still some evolution in the target selection, reflecting some uncertainties in the success of the current algorithms. Most target categories are now firm, at least for targeting at high galactic latitude. Primary problem is that a lot of data must be acquired and analyzed before we are sure of success, and the software that measures the parameters that we are interested in require large samples to develop. Convergence seems nigh, however, for the high latitude samples. At low latitudes, work remains on the photometry, and generally agreed NOT to attempt to select targets which require sophisticated color information. Probably G dwarfs and blind K giant (simple color and PM only) will be only targets at low latitude.

  20. SEGUE Software Status Version 5 of the spectroscopic pipeline, which includes much improved spectrophotometry and stellar radial velocities, is ready to run and test. Parameter estimation code is still under development, and it must be made production quality and incorporated into the processing pipeline (almost certainly as a separate pipeline step) Timescale approximately 1 year; data releases both internal and external before then will be ad hoc results of interim code. Interim, `test' reductions are keeping up with data acquisition.

  21. LEGACY Still about 400 square degrees of imaging (winter/early spring), and about 400 plates to finish in the north, primarily to fill in the gap in the center of the survey but also small missing areas elsewhere. We will begin Legacy observing in December.

  22. Calibration Two new efforts: Apache Wheel and ubercalibration Apache wheel is a system of fast (~8x normal scan rate) binned scans which create a network of well-calibrated photometry across the survey. Ubercalibration uses all overlaps in the survey, including strip-strip stripe-stripe oblique crossing scans-normal scans Apache wheel scans-normal scans Apace wheel—Apache wheel scans to create a global calibration. In the northern contiguous patch of the survey, it has been demonstrated to provide photometry with 1% errors in g, r, i, z; 2% in u in a prototype application, without benefit of Apache Wheel.

  23. SDSS sky with Apache Scans

  24. Calibration: Status Apache Wheel: Observations: Probably done, if all current data which is suspected good actually is. Photometric Pipeline modified appropriately and tested on binned data. Preparing now to reduce all Apache data, timescale ~ 1 month. Ubercalibration: As soon as Apache data are available, tests on full extant data set will be done; test version of code is ready, still need to reduce level of manual control. Integrating ubercalibration outputs into official data products is still being explored.

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