VOSA. Help and Documentation

Version 7.0, July 2021

1. Introduction
2. Input files
2.1. Upload files
2.2. VOSA file format
2.3. Single object
2.4. Manage files
2.5. Archiving
2.6. Filters
3. Objects
3.1. Coordinates
3.2. Distances
3.3. Extinction
4. Build SEDs
4.1. VO photometry
4.2. SED
4.3. Excess
5. Analysis
5.1. Model Fit
5.2. Bayes analysis
5.3. Template Fit
5.4. Templates Bayes
5.5. Binary Fit
5.6. HR diagram
5.7. Upper Limits
5.8. Statistics
6. Save results
6.1. Download
6.2. SAMP
6.3. References
6.4. Log file
6.5. Plots
7. VOSA Architecture
8. Phys. Constants
9. FAQ
10. Use Case
11. Quality
11.1. Stellar libraries
11.2. VO photometry
12. Credits
12.1. VOSA
12.2. Th. Spectra
12.3. Templates
12.4. Isochrones
12.5. VO Photometry
12.6. Coordinates
12.7. Distances
12.8. Dereddening
12.9. Extinction
13. Helpdesk
14. About
 
Appendixes
. Excess calculation
. Total flux calculation
. VOphot quality info

Use Case: From SED fitting to Age estimation. The case of Collinder 69

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Bayesian analysis.

The model chi-2 fit gives us the parameters for the best fit model. But a Bayesian analysis uses all the fits to estimate the probability fo each parameter value.

In order to try this option, we enter the "Model Bayes Analysis" tab and we see a form with the available theoretical models, so that we can choose what ones we want to use in the fit. In this case we decide to try Kurucz and BT-Settl-CIFIST models as we did in the chi-2 fit. Thus, we mark them and click in the "Next: Select model params" button.

For each of the models, we see a form with the parameters for each model and the available range of values for each of them. We choose the ranges that best fit our case and then click the "Next: Make the fit" button.

The fit and analysis process is performed asynchronously so that you don't need to stay in front of the computer waiting for the search results. You can close your browser and come back later. If the fit is not finished, VOSA will give you some estimation of the status of the operation and the remaining time.

When the process finishes VOSA shows us a list with, for each object and each model collection, the most probable value for each parameter and its probability.

And, if we click in one object name, we see a detailed information for that object with the probability of each parameter value and the corresponding plots.

 

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