Absolute flux calibrated spectra

Enrique Solano 3 years ago in Search for data updated by Archive Science Group 3 years ago 1

Dear Helpdesk,

I would need to find flux callibrated spectra in absolute units but it is not clear to me how to query the archive by this condition.

Thank you very much in advance for your help.


Dear Enrique,

   many thanks for using the ESO archive services.

There are different ways to achieve your goal:

  • If you are interested in a specific data collection, for instance the X-Shooter Spectral Library (XSL), you should refer to the associated release description, that contains information on how the data are reduced and the level of the calibration achieved.
  • It is possible to run a TAP query to obtain the list of all calibrated data by setting a WHERE condition on the o_calib_status column and requiring spectrum as dataproduct_type:
    SELECT TOP 10 * 
    FROM ivoa.ObsCore 
        o_calib_status = 'absolute' AND 
        dataproduct_type = 'spectrum'
  • If you are interested in a specific target, you can take advantage of the unofficial ESOAsg python package. For instance, if you want to collect all calibrated spectra present in the ESO archive associated with the star HD 057060, you can run:

    from ESOAsg import archive_observations
    from astropy.coordinates import SkyCoord
    # Define star position
    star_position = SkyCoord.from_name('HD 057060')
    # Get information on all spectra collected within 5" from the star
    eso_spectra = archive_observations.query_from_radec(star_position, radius=5., columns=['dp_id', 'instrument_name', 'o_calib_status'], data_types='spectrum')
    # Select absolute flux calibration
    cond_absolute = (eso_spectra['o_calib_status'] == 'absolute')
    # Download the data
    Note that this is equivalent to run this TAP query and download the retrieved dp_ids

Please let us know if this answer your question. We can also provide a more tailored feedback, but we will need some more details on the goal you need to achieve.

Enjoy your data!

The ESO Archive Science Group