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tests:astropars:astroparsii [2015/06/16 11:47] (current)
glennvdv created
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 +====== Second workshop stellar parameters ======
  
 +The purpose of these exercises is to simulate finding astrophysical parameters from Gaia data. We will focus on using the low resolution BP/RP data for this, but will include the information from astrometry and possibly also high-resolution RVS data. The exact aim depends on which challenges are suggested and which are popular. There may arise some constraints ​ connected to our ability to simulate particular datasets. ​
 +
 +
 +Package is organized by Rene Andrae and Kester Smith
 +
 +
 +=== Challenges ===
 +
 +  * [[:​tests:​astropars:​challenge1|Challenge 1: Moving groups]]
 +  * [[:​tests:​astropars:​challenge2|Challenge 2: Reference stars]]
 +  * [[:​tests:​astropars:​challenge3|Challenge 3: Fit BP/RP and RVS]]
 +  * [[:​tests:​astropars:​challenge4|Challenge 4: Build realistic test data]]
 +
 +=== Default Data Package ===
 +
 +**NOTE: updated 14/​10/​2014**
 +
 +There was an error in the first version of this data set. Please download the new version. ​
 +
 +Here is the first set of mock data. 
 +This has been made as follows;
 +  *  Obtain a sample of objects from the Gaia Universe Model Snapshot catalogue. Coordinates are l,b=0,80 (so a sparse halo field). There are just over 2000 objects. ​
 +  * Use Gog to produce BP,RP, RVS spectra. Note: there are few RVS spectra ​
 +  * Gog results are held in the file gums_0_80_v1.dat. Data include position, proper motion, parallax, Radial velocity, Gaia band fluxes, and basic astrophysical parameters. ​
 +  * BP, RP and RVS spectra are in separate files (identify with the sourceId included in the filename) The columns are wavelength,​flux,​ error
 +  * BP,RP wavelengths are currently in '​pseudo-wavelengths'​ (~pixel numbers). I will try to provide an approximate true wavelength scale soon.
 +  * I will provide a mean instrument model (line spread function + sensitivity function) soon. 
 +
 +In the meantime, please have a look at this data and let me have any comments re: ease of use (or more likely the opposite), any suggestions ​ etc etc. 
 +
 +The data set is in the mpia public ftp site (mpia-hd.mpg.de),​ in pub/​smith/​gaiachallenge,​ name gums_0_80_v1.tar
 +
 +Also available;
 +  *  bprpWavelengths.dat , which are the wavelengths in nm
 +  *  bprpTransmission.dat , which is the total transmission function (column 1: bp, column 2: rp)
 +  *  bprpLsfs.tar , a set of LSFs, one for each pixel. The wavelengths are indicated in the filename. The offsets are in pixel coordinates. ​
 +
 +
 +
 +
 +
 +
 +
 +=== Challenges ===
 +
 +
 +== Challenge 1 == 
 +
 +Two datasets are available from the mpia public ftp site (mpia-hd.mpg.de),​ in 
 +pub/​smith/​gaiachallenge/​andrae,​ name andraeChallengeV1.tar. ​
 +
 +Unpack the tar archive to obtain;
 +
 + * nominal-grid-MARCS.csv ​ - basic APs and noise-free spectra for the a grid of known stars
 + * test-data-MARCS-reduced.csv - basic data (position,​astrometry,​photometry) fro a set of test sources
 + * test-spectra/​* - files containing noisy  BP/RP data for the test data. 
 +
 +The challenge is to estimate the APs (Teff, logg, Fe/H, AV) for the test spectra.
 +
 +
 +== Challenge 2 == 
 +
 +Set of reference spectra supplied by Paula Jofre. ​
 +
 +These are available at the MPIA anonymous ftp site. cd to
 +pub/​smith/​gaiachallenge/​jofre and pick up the tar file. 
 +
 +The file contains bp and rp spectra for 32 stars, plus the file jofre_v1.dat
 +which contains the positions, astrometry, photometry, RV and VsinI for each source. ​
 +
 +**UPDATE** Also available jofre_v1_rvs.dat,​ containing rvs spectra for all stars. ​
 +
 +This sample has been selected from observations taken with high resolution from the
 +Ground. These stars are candidates to be reference stars for Gaia in the near
 +future. ​ The high-resolution spectra were then convolved and transformed to BP-RP
 +spectra using GOG.  The challenge is to try to determine their parameters, in a
 +totally blind way, and then we can during the workshop compare with high-resolution
 +ground based analyses. ​
 +
 +
 +== Challenge 3a ==
 +
 +Data for several **moving groups** was run through GOG. The results are available on
 +the ftp site in directory murphy in file movingGroupsKnown.tar
 +
 +The challenge is just to look at the data! 
 +
 +
 +  ​
 +
 +// From: Andy Casey //
 +
 +See how well the working group can recover astrophysical parameters for a sample of N (where N is ~"​large"​) stars. The spectra could be interpolated from model spectra, doppler shifted,​  ​ resampled and convolved with some profile which would roughly represent the Gaia RVS, and with noise + jitter ​  ​added. Making it a blind test would be much more fun.
 +
 +
 +
 +// From: Andy Casey //
 +
 +Fitting low-resolution BP/RP spectra and high-resolution (AMBRE grid from Gaia-ESO, not RVS from Gaia) spectra simultaneously. Does it outperform fitting each individually?​ High-resolution model grid is from MARCS and BP/RP are provided in MARCS, too.
 +  ​
 +
 +// From: Maria Bergemann //
 +
 +the performance
 +of our new Bayesian pipeline [[http://​adsabs.harvard.edu/​abs/​2014MNRAS.443..698S |(Schoenrich & Bergemann 2013)]] on the Mock Gaia photometry+RVS+parallax
 +data samples.
 +
 +
 +
 +
 +// From: Simon Murphy //
 +
 +Finding *new* young moving groups in the solar neighbourhood (<1 kpc say) using
 +a combination of BP,RP photometry, astrometry and RVS velocities.
 +  ​
 +
 +// From: Kester Smith //
 +
 +Identify the red clump.
 +
 +
 +// From: Kester Smith //
 +
 +Identify the blue horizontal branch.
 +
 +// From: Kester Smith //
 +
 +identify extreme metallicity stars (ultra low, or very high alpha enhanced, or some other extreme)
 +
 +// From: Rene //
 +
 +validation of HR diagram: do all relevant types of stars exist in test data? do they end up in the right region of the HRD?
 +
 +
 +
 +
 +=== Useful references ===
 +
 +  * CU8 APSIS: [[http://​adsabs.harvard.edu/​abs/​2013A%26A...559A..74B|Bailer-Jones et al. (2013)]], [[http://​adsabs.harvard.edu/​abs/​2012MNRAS.426.2463L|Liu et al. (2012)]]
 +  * Combining photometry, spectroscopy & astrometry: [[http://​adsabs.harvard.edu/​abs/​2011MNRAS.411..435B|Bailer-Jones (2011)]], [[http://​adsabs.harvard.edu/​abs/​2014MNRAS.443..698S |Schoenrich & Bergemann (2013)]]
 +  * Gaia Object Generator (GOG): [[http://​adsabs.harvard.edu/​abs/​2014A%26A...566A.119L|Luri et al. (2014)]]
 +  * Gaia Universe Model Snapshot (GUMS): [[http://​adsabs.harvard.edu/​abs/​2012A%26A...543A.100R|Robin et al. (2012)]]
 +  * Benchmark stars: [[http://​adsabs.harvard.edu/​abs/​2014A%26A...564A.133J|Jofre et al. (2014)]], [[http://​adsabs.harvard.edu/​abs/​2014A%26A...566A..98B|Blanco-Cuaresma et al. (2014)]]
 +  * Conversion to Gaia magnitudes: [[http://​adsabs.harvard.edu/​abs/​2010A%26A...523A..48J|Jordi et al. (2010)]]
 +  * Extinction laws: [[http://​adsabs.harvard.edu/​abs/​1989ApJ...345..245C|Cardelli et al. (1989)]], [[http://​adsabs.harvard.edu/​abs/​1999PASP..111...63F|Fitzpatrick (1999)]]
tests/astropars/astroparsii.txt ยท Last modified: 2015/06/16 11:47 by glennvdv