Matilija University 1 year ago updated by Deborah Baines 1 year ago 1

I have not yet found the display function in ESA Sky which allows us to display known and imaged Quasars, AGN and Candidates.

From the 1.5 Million or so in our database to date. Viz the Million Quasars (Milliquas) catalog, v7.10, 15 April 2023


How do we toggle/display all known, imaged, Quasars for viewing and exploring in ESA Sky?

Or Open Clusters, Globular Clusters, Dwarf Galaxies, Galaxies, etc.?

Thank you. I was not able to get any assistance from the SDSS for viewing the imaged Quasars in the Catalog

Millennium Twain

member of the ESA Gaia Research Community


Dear Millennium Twain,

From what I understand, this is a very large catalogue that you'd like to view in ESASky, and to possibly filter for certain types of objects? 

I'm happy to tell you that ESASky now provides access to VizieR and the 4 versions of the Milliquas catalogue are appearing in ESASky. When I search in VizieR, the latest version of the catalogue appears to be: The Million Quasars (Milliquas) catalogue, version 7.2 (Flesch, 2021); the VII/290/catalog, and I can find it and load it in ESASky by doing the following:

  • Click on the 5th icon in the top left (when hovering it says 'Explore data from external data centres in this region')
  • Click on the 'VizieR' tab
  • In the search field, search for 'Flesch' or even better, search for 'VII/290/catalog'
  • Open the 'VII_nonstellar' tree
  • If you want to load sources within the field of view displayed in ESASky, toggle on the 'FoV restricted' button in the top right of the External Data Centres window and then select the first icon on the left of the catalogue, in the Open column (when hovered over it says 'open table'). 
  • By toggling off the 'FoV restricted' button you will load the whole table, however, please note this is limited to 10,000 sources so as not to overload the browser. What you can next do is filter the query for quasars, for example, by filtering the 'Type' column in the catalogue. You can do this using the ADQL functionality within ESASky (select the 3rd icon in the Query column (when hovered over it says 'create a custom ADQL query'). And you can type something like the following (and see the image below): 

SELECT TOP 10000 * FROM "VII/290/catalog"

WHERE 1=CONTAINS( POINT('ICRS', RAJ2000, DEJ2000), CIRCLE('ICRS', 235.65,10.0, 10.0))

AND Type = 'Q'

The above ADQL code brings back the first 10000 rows (TOP 10000) and all columns (*) from the VII/290 catalogue (FROM "VII/290/catalog") centred at coordinates RA=235.65, DEC = 10.0 and a radius of 10.0 degrees (2nd line) and also only selecting Quasars (Type = 'Q'). 

Image 108

Note, this type of query is still restricted to returning 10000 objects in the sky (even if you remove TOP 10000). Let us know if you need to visualise more objects in the sky or the type of use case you are trying to do. 

To find out more about this functionality and about ADQL commands, please read our help pages here: https://www.cosmos.esa.int/web/esdc/esasky-interface#EXTTAP

I hope all this helps.

Best regards,

Deborah, on behalf of the ESASky team