Download - Astronomical Spectroscopy in the VO era: VOSpec Pedro Osuna

ESAVO/European Space Astronomy Centre (ESAC)Villafranca del Castillo, MADRID (SPAIN)Pedro OsunaASVOWS 21-23 Mar 2007 ESAC

Astronomical Spectroscopy in the VO era: VOSpec

Pedro OsunaIsa Barbarisi, Jesus Salgado, Andrea Laruelo

European Space Astronomy Centre (ESAC)Science Archives and VO Team


Making data available in the Internet

Create document

WEB SERVER

robots


Making data available in the VO

Create service

SSA SERVER


Making data available in VO: DAL Toolkit

Config Files

SpectraFITS Files

Ingestor

DB

ServerDAL Request

VOTable

File Sys


VOSpec Main Features• Handle SSAP spectra• Open local Spectra (Fits or VOTable)• Create a SED of spectra coming from a

wide range of different providers registered in the VO Registry (http://esavo.esa.int/registry) and also coming from local data

• Create SSAP Wrapper with your own set of local spectra and immediately display it

• Graphic options like color modification, zoom, unzoom, change spectra visualization, change units etc..

• Save results as Image/VOTable• Math operations like Polynomial,

BlackBody fitting, Gaussian, Nomalization, DeReddening, Red-shift, Luminosity Differences etc.

• Access to Theoretical Spectra through TSAP and Spectral Atomic Lines through SLAP

• Interoperability with other vo-aware tools through Plastic Technology


De-Reddening

• Interstellar reddening is a phenomenon associated with interstellar extinction where the spectrum of electromagnetic radiation from a radiation source changes characteristics from that which was emitted.

• Reddening occurs due to the light scattering off dust and other matter in the interstellar medium. It preferentially removes shorter wavelength photons from a radiated spectrum while leaving behind the longer wavelength photons (in the optical, light that is redder), leaving the spectroscopic lines unchanged

• VOSpec povides support to this phenomenon allowing to apply the Calzetti, Cardelli O’Donnel or LMC formula, depending by the case.

• Please visit the VOSpec User Manual to see the video of the De-Reddening functionality.


De-Reddening – IRAS 10178-5958 case


Theoretical Spectra Access in VOSpec

• VOSpec allows the user to rescale theoretical spectra using real spectral data for the object to be studied.

• Even if there are many differences between theoretical and real spectra, it’s been studied a solution to unify them in a common access protocol in order to visualize them in the same plot

• Main differences between both kind of spectra are the following:

- Models have specific input parameters- Theoretical Spectra are not normalized


Simple Line Access through VOSpec

• There is a scientific need to have access to spectral line databases in the VO. Many science cases could make use of this kind of access

• VOSpec provides access to Atomic Line Databases through the Simple Line Access Protocol (SLAP)

• Please visit the VOSpec User Manual to see the video of the SLAP functionality.


Best Fit fitting toolMOTIVATION MOTIVATION

Currently, to find the model that best fits a given SED:•Choose parameters manually•Inspect result visually (“Chi-by-eye”)•Modify parameters manually•Reinspect visually•Loop… GOAL

Best Fit finds thebest fit modelautomatically

METHOD

Levenberg-Marquardt Chi-squareminimization algorithm


Best Fit step by step

Selecting TSA server

Initial model

Best fit model

minimizationproccess

Select TSA server

Select initial parameters


Plastic Technology and Applications

• PLASTIC is a protocol for communication between client-side astronomy applications. Through PLASTIC applications can do tasks such as instruct each other to load Spectra, VOTables, highlight a subset of rows or load an image of a particular area of sky. Although such operations are quite simple, they enable powerful collaborations between tools. The philosophy is that the astronomer should have a suite of interoperating tools at his disposal, each of which does one thing well and which can be composed according to his particular needs.

• VOSpec allows registration to the Plastic Hub and it can interoperate with other VO-aware tools like Aladin, Astroscope, VOQuest etc

• Please visit http://plastic.sourceforge.net for more details about the project

Sending spectra from Astroscope to VOSpec through Plastic

Sending spectra from Aladin to VOSpec through Plastic


Future implementations on VOSpec

You name it, we implement it.

See VOSpec at work: http://esavo.esac.esa.int/vospec/

And the User Manual at: http://esavo.esac.esa.int/VOSpecManual/