Astronomical Spectroscopy and the Virtual Observatory ESAC, March 2007 VO tools and cross-calibration Pedro García-Lario European Space Astronomy Centre Herschel Science Centre

Astronomical Spectroscopy and the Virtual Observatory ESAC, 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 CLASSICAL OBSERVATORY VIRTUAL OBSERVATORY

Astronomical Spectroscopy and the Virtual Observatory ESAC, 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, March 2007 Change of units tool

Astronomical Spectroscopy and the Virtual Observatory ESAC, March 2007 Synthetic photometry tools    MSX photometry  IRAS photometry  Synthetic photometry

Astronomical Spectroscopy and the Virtual Observatory ESAC, March 2007 Statistical analysis tools

Astronomical Spectroscopy and the Virtual Observatory ESAC, March 2007 Statistical analysis tools

Astronomical Spectroscopy and the Virtual Observatory ESAC, March 2007 Aperture photometry tools J = ± 0.06 H = ± 0.04 K = ± 0.04 J H K V DSS 2MASS 2MASS2MASS

Astronomical Spectroscopy and the Virtual Observatory ESAC, March 2007 Aperture photometry tools J = ± 0.06 H = ± 0.04 K = ± 0.04 J H K V DSS 2MASS 2MASS2MASS    

Astronomical Spectroscopy and the Virtual Observatory ESAC, March 2007 Aperture photometry tools J = ± 0.06 H = ± 0.04 K = ± 0.04 J H K V DSS 2MASS 2MASS2MASS Real life can be even more complicated…

Astronomical Spectroscopy and the Virtual Observatory ESAC, March 2007 Rebinning tools

Astronomical Spectroscopy and the Virtual Observatory ESAC, March 2007 Spatial convolution tools AKARI Reflection nebula IC 4954 IRCFIS 90  m9  m IRAS 12  m

Astronomical Spectroscopy and the Virtual Observatory ESAC, March 2007 Images Spectra Catalogues The cross-calibration ‘world’ Models Other spectra Other catalogues Other Images 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 points Filter information

Astronomical Spectroscopy and the Virtual Observatory ESAC, 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: “You don’t have to do everything with the VO” (A.Richards)

Astronomical Spectroscopy and the Virtual Observatory ESAC, 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, 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’ ;-)