Evaluation of 6dF Data

1
Evaluation of 6dF Data

• Lesa Moore
• Macquarie University
• Honours Project 2003
• Supervisor Quentin Parker MU/AAO

2
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

3
Target and Observed Fields One field
studied to date
My first field!!
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Field Details

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

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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)

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Comparison Spectra - 1
IRAF data not flux-calibrated
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Comparison Spectra - 2
IRAF data not flux-calibrated
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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
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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 - cant afford
  this!
• Heliocentric correction incorrectly applied,
  correct on /net/aaowfi/data1/will/runz/runz6df_ma
  y03

10
Arc spectrum R - HgCdNe
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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
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IRAF
6dFDR

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

13
Arc spectrum R - HgCdNe
14
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

15
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
43
69
78
RUNZ VR
16
RUNZ-VR misidentifications 11/109
V 21/109 R 28/109
z 0.09
17
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)
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Mean uncertainty in x-correlation 109 galaxies
RUNZ R 79 km/s (z 0.0003)
RUNZ V 84 km/s (z 0.0003)
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
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X-correlation R data 57
well-matched galaxies
Error bars are x-correlation uncertainties
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X-correlation R data All
109 galaxies
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Line Measurements 9 galaxies
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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
• Cant 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

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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

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Thanks

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