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Observa(ons mo(vated by SDSS colors relevant to Gaia
Francesca DeMeo The Solar System before and a;er Gaia
Thursday May 5, 2011
Outline
• SDSS: What is it?
• Results: What are they?
• New Observa(ons: What did SDSS mo(vate?
• Limita(ons: What are they?
• Relevance: How does this relate to GAIA?
Sloan Digital Sky Survey
• Purpose: A mul(-‐filter imaging and spectroscopic redshi; survey -‐ imaged 930,000 galaxies and more than 120,000 quasars.
• Timeline: Began in 2000 and is s(ll con(nuing
• Asteroids: Over 100,000 unique moving objects observed
• Wavelengths: Five filters, u, g, r, i, z (λ = 0.355, 0.469, 0.617, 0.748, 0.893 um)
SDSS Main Results
Parker et al., 2008
• Analyze color measurements to dis(nguish broadest asteroid groups for ~100,000 objects
SDSS Main Results
Parker et al., 2008
• Analyze color measurements to dis(nguish broadest asteroid groups for ~100,000 objects
• Determine color gradient in orbital element space across the Main Belt
SDSS Main Results
Parker et al., 2008
• Analyze color measurements to dis(nguish broadest asteroid groups for ~100,000 objects
• Determine color gradient in orbital element space across the Main Belt
• Isolate families based on colors and orbits
• Inspect background objects
More SDSS Results Astrometry – Color Variability – Light Curves – Families – Space Weathering – Trojans – Comets
Follow-‐up Observa(ons
Moskovitz et al. 2008
V-‐types
Masi et al. 2008
Follow-‐up Observa(ons
Roig et al. 2008 Duffard & Roig 2009 Hammergren et al. 2011
V-‐types
Roig & Gil-‐Huhon 2006
Follow-‐up Observa(ons Families
Mothe-‐Diniz et al. 2005
Follow-‐up Observa(ons
Burbine et al. 2011
7472: The Second O-‐Type
Follow-‐up Observa(ons
Moskovitz et al. 2008b
10537: A unique object
Duffard & Roig 2009
Follow-‐up Observa(ons
Class = “Bus-‐DeMeo”
Follow-‐up Observa(ons
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A-‐types Score: 1 out of 3
Limita(ons of SDSS
• Low resolu(on
• No albedo measurements
• Large errors and variability
• Visible-‐only data
Limita(ons of SDSS Low resolu(on
(C-‐, X-‐ complexes degenerate)
C-‐ complex example in SDSS
Limita(ons of SDSS
DeMeo 2010, PhD Thesis
No Albedo
Wide variety of albedos among classes Spectrally degenerate E, M, P classes
X = E M P
E: pv > 0.3 M: 0.075 < pv < 0.3 P: pv < 0.075
Limita(ons of SDSS Variability greater than errors
Limita(ons of SDSS Variability greater than errors
Limita(ons of SDSS Visible-‐only colors
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5
Refl
ect
an
ce
Wavelength (microns)
3734 was Ld
269 was Ld
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5
Refl
ect
an
ce
Wavelength (microns)
3734 was Ld now L
269 was Ld now D
Limita(ons of SDSS The near-‐ir may surprise you
Limita(ons of SDSS The near-‐ir may surprise you
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5
Refl
ect
an
ce
Wavelength (microns)
Limita(ons of SDSS The near-‐ir may surprise you
0
0.5
1
1.5
2
2.5
3
3.5
0 0.5 1 1.5 2 2.5
Refl
ect
an
ce
Wavelength (microns)
Relevance to Gaia
• Resolu(on: Gaia will be able to dis(nguish some of the subtle features (for C, X) that SDSS cannot
• Albedo: Will combine albedo with spectroscopy: can separate degenerate spectra and further dis(nguish among a single class
• Precision: Will have beher accuracy and precision: less confusion with the errors
• But – s(ll vis-‐only so must be aware of degeneracy in vis wavelengths – this provides opportunity for follow-‐up observa(ons.