CDS
CDS is experiencing a cybersecurity incident within its network of servers located in Strasbourg. Our teams are taking steps to assess and mitigate the issue. This includes taking some systems offline to help protect them. As a consequence, access to SIMBAD, VizieR, Aladin image surveys, X-Match and other services hosted on our main site cds.unistra.fr is currently degraded.
We apologize for any inconvenience this issue may cause. Our teams are doing their best to investigate the incident, and restore full access to the services located in Strasbourg as soon as possible.
This page provides some alternatives for accessing some of the services in the meantime.
Sesame / object name resolver 
A mirror of Sesame is running on the IDIA server (South Africa) : https://vizier.idia.ac.za/viz-bin/Sesame
The API endpoint is of the form : https://vizier.idia.ac.za/viz-bin/nph-sesame/{option}?{object}
For example, to query object Vega and get XML output: https://vizier.idia.ac.za/viz-bin/nph-sesame/-ox/?Vega
Another mirror of Sesame is running at CfA Harvard : https://vizier.cfa.harvard.edu/viz-bin/Sesame
SIMBAD 
At CfA Harvard
A mirror of the SIMBAD service is accessible at : https://simbad.cfa.harvard.edu/simbad/ It contains data ingested up to 2026-10-14.
A mirror of the SIMBAD TAP service is available here : https://simbad.cfa.harvard.edu/simbad/sim-tap/
At IDIA (South Africa)
A mirror of the SIMBAD service is accessible at : https://simbad.idia.ac.za/
A mirror of the SIMBAD TAP service is available here : https://simbad.idia.ac.za/simbad/sim-tap/
astroquery.simbad
You can configure astroquery to use a specific mirror to query SIMBAD.
The mirror site used by astroquery.simbad can be configured either:
- In each script:
>>> from astroquery.simbad import Simbad
>>> my_simbad = Simbad()
>>> my_simbad.server = "simbad.harvard.edu"
>>> result_table = my_simbad.query_object("HD 8745")
>>> print(result_table)
main_id ra dec coo_err_maj coo_err_min coo_err_angle coo_wavelength coo_bibcode matched_id
deg deg mas mas deg
--------- -------------- -------------- ----------- ----------- ------------- -------------- ------------------- ----------
HD 8745 21.72418762496 37.49220928213 0.0206 0.0205 90 O 2020yCat.1350....0G HD 8745(works with astroquery >=0.4.8)
- Permanently on you machine:
To do so, go to the file ~/.astropy/config/astroquery.cfg and edit the [simbad] section. There should be a commented line:
#server = simbad.cds.unistra.frReplace by:
server = simbad.cfa.harvard.eduTroubleshooting: if the file is not there, you might have changed the default location for astropy configuration files. You can find yours with:
from astropy.config import get_config_dir_path
print(get_config_dir_path())VizieR 
Mirrors
Several mirrors of VizieR are available :
- at IDIA (South Africa) : https://vizier.idia.ac.za/viz-bin/VizieR
- at CfA Harvard : https://vizier.cfa.harvard.edu/viz-bin/VizieR
- at NAOJ (Japan) : http://vizier.nao.ac.jp/viz-bin/VizieR
- at China-VO : http://vizier.china-vo.org/viz-bin/VizieR
Note that the large catalogues (such as Gaia DR3 I/355) are not available on all mirrors. You can access Gaia data from the ESA archive.
astroquery.vizier
The mirror site used by astroquery.vizier can be configured either:
- In each script:
from astroquery.vizier import Vizier
my_vizier = Vizier(vizier_server="vizier.cfa.harvard.edu")
my_vizier.find_catalogs("SDSS")- Permanently on you machine:
To do so, go to the file ~/.astropy/config/astroquery.cfg and edit the [vizier] section. There should be a commented line:
#vizier_server = vizier.cds.unistra.frvizier_server = vizier.cfa.harvard.eduTroubleshooting: if the file is not there, you might have changed the default location for astropy configuration files. You can find yours with:
from astropy.config import get_config_dir_path
print(get_config_dir_path())Aladin 
Aladin Lite
Instead of using the Aladin Lite source code linked from aladin.cds.unistra.fr, the latest version of Aladin Lite JavaScript source code can be downloaded from here : aladin.js.
A fallback version of the Aladin Lite previewer is available on this website : https://aladin.cds.unistra.fr/AladinLite/
It includes a list of HiPS available from mirror sites, an object name resolver, and link to SIMBAD mirror.
HiPS surveys
Links to alternative servers providing the most popular HiPS image surveys :
- DSS color - CDS/P/DSS2/color
- 2MASS color - CDS/P/2MASS/color
- SDSS9 color - CDS/P/SDSS9/color
- PanSTARRS irg - CDS/P/PanSTARRS/DR1/color-i-r-g
- AllWISE color - CDS/P/allWISE/color
A complete list of HiPS surveys available is listed here.