astronomical spectroscopy and the virtual observatory esac, 21-23 march 2007 vo tools and...
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Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
VO tools and cross-calibration
Pedro García-LarioEuropean Space Astronomy Centre
Herschel Science Centre
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
Calibration vs. Cross-Calibration
CALIBRATION
– Individual source analysis
– Single instrument
– Single spectral range
– Single units
– Single beam/aperture/filter
– Primary calibrators
– Raw data products
– Detailed interactive analysis
– Dedicated tools
CROSS-CALIBRATION
– Multiple source analysis
– Multiple instruments
– Multi-wavelength
– Multiple units
– Multiple beam/aperture/filter
– Secondary calibrators
– Calibrated data products
– Quick look / statistical analysis
– Multi-mission (common) tools
CL
AS
SIC
AL
OB
SE
RV
AT
OR
Y
CL
AS
SIC
AL
OB
SE
RV
AT
OR
Y
VIR
TU
AL
OB
SE
RV
AT
OR
Y
VIR
TU
AL
OB
SE
RV
AT
OR
Y
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
The ideal cross-calibration tool• Data browser capabilities
– Fast retrieval of all available images / photometry / line-range spectroscopy for a given source
– Flexible to incorporate additional data as soon as they become available
• Model browser capabilities– On-the-fly retrieval/selection of models, accompanied by basic fitting tools
• Able to deal simultaneously with different units – On-the-fly change of units
• Able to deal simultaneously with different spectral/spatial resolution data
– Rebinning tools / convolution tools
• Able to deal simultaneously with different beam/aperture/filters– Beam/aperture/filter corrections, including synthetic photometry from spectra
• User friendly graphical interface showing the results of the above in a common environment (platform independent)
• Quick look analysis / statistical tools– To evaluate e.g. goodness of fits and overall consistency of absolute flux calibration of
large data sets
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
Change of units tool
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
Synthetic photometry tools
MSX photometry IRAS photometry Synthetic photometry
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
Statistical analysis tools
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
Statistical analysis tools
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
Aperture photometry tools
J = 13.43 ± 0.06H = 12.07 ± 0.04K = 11.18 ± 0.04
J
H K
VDSSDSS 2MASS2MASS
2MASS2MASS 2MASS2MASS
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
Aperture photometry tools
J = 13.43 ± 0.06H = 12.07 ± 0.04K = 11.18 ± 0.04
J
H K
VDSSDSS 2MASS2MASS
2MASS2MASS 2MASS2MASS
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
Aperture photometry tools
J = 13.43 ± 0.06H = 12.07 ± 0.04K = 11.18 ± 0.04
J
H K
VDSSDSS 2MASS2MASS
2MASS2MASS 2MASS2MASS
Real life can be
even more complicated…
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
Rebinning tools
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
Spatial convolution tools
AKARI
IRCFIS
90 m 9 m
IRAS
12 m
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
ImagesSpectra
Catalogues
The cross-calibration ‘world’
Models
Otherspectra
Othercatalogues
OtherImages
Rebinning/flux units Convolution/surface brightness units
Colour correction/photometric units
Filter information/Synthetic photometry
Beam information/Aperture photometry
Spectral resolution information
Beam information
Photometric zero pointsFilter information
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
The (my) ideal Virtual Observatory• A system which allow users to interrogate multiple data centres and
services in a seamless and transparent way to access and visualize fully characterised astronomical data and models of very heterogeneous nature through specific protocols in a common environment…
• … accompanied by some data manipulation tools like e.g. change of units, simple arithmetics, statistical tools, spatial convolution, rebinning, synthetic photometry, aperture photometry
• … powerful to deal with large number of data sets: (over)-plotting capabilities, automated spectral/imaging classification,…
• … plus a few basic tools for quick look analysis: model fitting, line identification, redshift, radial velocity, extinction correction,…
• … which provides the capability to export your VO-processed data to your local environment according to your preferred view to complete your analysis with dedicated tools if needed
Remember: Remember: “You don’t have to do everything with the VO”“You don’t have to do everything with the VO”(A.Richards)(A.Richards)
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
Common problem(s)• Data characterisation model
• Use of large, uniformly calibrated data sets usually helps but it is not enough
• Full characterisation is not always possible
• Need of extra information not yet available through the VO in many cases
• Beam profile/aperture description, filter transmission profiles, photometric zero points, spectral resolution information are only examples of additional information needed to properly communicate existing VO applications (e.g. through PLASTIC)
• Quality information is a world apart because of its complexity
• Filter services and footprint services are a step forward
• Need of a common access protocol to handle this information (as part of the metadata?)
• Data providers must be conscious that this additional information is essential to handle their data properly in a VO environment
• Other information not so critical but also useful, e.g.: Object type (to facilitate queries), time info in catalogues (to generate light curves), links to publications, etc.
Astronomical Spectroscopy and the Virtual Observatory
ESAC, 21-23 March 2007
Summary
• VO tools and cross-calibration share many common objectives and deal with many common problems
• VO tools are already (or soon will be) able to collect and deal simultaneously with multi-wavelength images, photometry, line and range spectroscopy from an unlimited number of ground-based and space facilities
• Full data characterisation is the main common problem; some information is not yet properly handled by the VO
• Exploring synergies between VO and cross-calibration seems convenient and joining efforts ‘unavoidable’ ;-)