Evaluation of 6dF Data Lesa Moore Macquarie University Honours Project 2003 Supervisor: Quentin Parker MU/AAO

Goals of Honours Project Independent evaluation of results from 6dFDR and RUNZ Comparison analysis using IRAF dofibers, line measurements, xcsao and emsao Test 6dFDR and RUNZ for accuracy and systematic errors by comparison with IRAF results Test 6dFDR and RUNZ for repeatability Report to survey team with results and recommendations

Target and Observed Fields One field studied to date *Plots show full hemisphere (360 deg, Celestial equator to SCP) Top: targets selected from catalogues (NIR and optical imaging surveys) *Targets plot shows density scale (number of objects per square degree) *Zone of avoidance – the Milky Way Bottom: Observed fields as at April 2003 – circles are 6 degrees in diameter *Gratings have been changed since the commencement of the survey *Key: Green reflection gratings, grey transmission gratings *The field I’ve been studying (first of many) is centred at 9h 24m -30 30 17,000 square degrees per hemisphere 4,000 square degrees in zone of avoidance Adaptive tiling algorithm – allows for varying number density of targets (overlap, some fields need to be observed twice) Over 1000 fields My first field!!

Field Details 0924m30 Observed 20/3/2002 Reflection gratings 600V: 4000-5600Å; 316R: 5500-8500Å 109 spectra, 28 parked fibres, 13 skies

Batch-Mode Reduction 6dFDR, RUNZ on separate V, R and spliced VR data using 6dFDR arc-line lists (see later!) IRAF dofibers on V, R data using my own arc-line lists (NIST Atomic Spectra Database: http://physics.nist.gov/cgi-bin/AtData/lines_form) IRAF xcsao on R grating data only No heliocentric correction applied (raw redshifts only)

Comparison Spectra - 1 IRAF data not flux-calibrated

Comparison Spectra - 2 IRAF data not flux-calibrated

Signal-to-noise comparison (mean for 109 galaxies) RUNZ R 10.3500 RUNZ V 9.4253 RUNZ VR 8.8476 IRAF R 3.4753 Data from: IRAF - measured in splot; RUNZ - 0924Rcom.sdfz.zlog

Problems encountered Discovered HgCdNe line list has too few Ne, extra Ar and miscellaneous lines High-dispersion data: only 13 good arc lines in HgCdHe line list: - 6dFDR throws away 3 worst lines - can’t afford this! Heliocentric correction incorrectly applied, correct on: /net/aaowfi/data1/will/runz/runz6df_may03

Arc spectrum R - HgCdNe

R-arc line-identification compared (subset of 10 fibres) IRAF 6dFDR # lines in line list 61 46 mean rms of disp function 0.1930 0.1584 mean # lines fitted 39.5 29.5 Data from: IRAF – arcapid.t.ms; 6dFDR – arclist006.dat On 108 spectra, mean rms IRAF 0.1816; 6dFDR 0.1539

Line lists and matched lines in dispersion functions IRAF 6dFDR Line lists and matched lines in dispersion functions Red: neon lines to be added Blue: 6dfdr desert

Arc spectrum R - HgCdNe

Even with extra lines from NIST ASD, still only 16 good lines Arc spectrum V - HgCdHe Not enough lines in high-dispersion data to be used for Dn-s measurements? Even with extra lines from NIST ASD, still only 16 good lines

Agreement: batch x-cor results V data, R data and VR data compared Dz ≤ 0.0005 (150 km/s) out of 109 spectra RUNZ R RUNZ V 45 IRAF R 57 43 69 78 RUNZ VR

RUNZ-VR misidentifications 11/109

R data: 109 galaxies - r-h plots from both x-correlations - “disagrees” are low S/N spectra Data from: IRAF – xcsao.log; RUNZ – read from display (r writes to log)

Mean uncertainty in x-correlation 109 galaxies RUNZ R ± 79 km/s (z ± 0.0003) RUNZ V ± 84 km/s RUNZ VR ± 59 km/s (z ± 0.0002) IRAF R ± 41 km/s (z ± 0.0001) Data from: IRAF – xcsao.log; RUNZ – verr from 0924Rcom.sdfz.zlog IRAF uses 12 templates, RUNZ uses 8 templates

X-correlation R data 57 well-matched galaxies Error bars are x-correlation uncertainties

X-correlation R data All 109 galaxies

Line Measurements – 9 galaxies

Summary Results S/N appears higher in RUNZ than in IRAF Line lists should be reviewed 6dFDR should have “retain all lines” option Update all versions of RUNZ to do heliocentric correction properly Can’t batch-process – still need to check for misidentifications Disagreements between methods and gratings on low S/N data not a matter of concern X-cor uncertainty could be quoted on RUNZ screen display and should be mentioned in online database May reduce uncertainty by including more templates for RUNZ Overall z values concur in cases of proper identification … and keep in mind …

Results from these analyses are preliminary! Many more fields will be studied VPH grating data will be compared with reflection grating data Repeatability of measurements will be tested on repeat observation if possible

Thanks Anglo-Australian Observatory Wide-Field Astronomy Unit, Edinburgh Macquarie University 6df Galaxy Survey Team (37 members) Will Saunders, AAO Quentin Parker, MU/AAO