Aladin Desktop is a powerful, interactive sky atlas developed by the Centre de Données astronomiques de Strasbourg (CDS). It serves as a key visual platform for astronomers and astrophysicists to explore, analyze, and cross-match astronomical data from diverse sources. Originally designed for accessing and displaying astronomical catalogs and images, Aladin has evolved into a versatile, multi-purpose tool, essential in modern multi-messenger astronomy, particularly for gravitational-wave (GW) follow-up observations.
Core Capabilities
Sky visualization with HiPS support. Aladin enables navigation of the celestial sphere using the HiPS (Hierarchical Progressive Surveys) standard, which allows scalable and efficient access to high-resolution astronomical imagery. Users can seamlessly browse data across multiple wavelengths (optical, infrared, ultraviolet, radio) and display wide-field surveys such as DSS, 2MASS, Gaia, and Pan-STARRS with high performance and detail.
Catalog access and overlay. Users can overlay a wide range of astronomical catalogs—such as from SIMBAD, VizieR, GLADEnet, or custom datasets—directly onto images, facilitating rapid source identification and classification. Advanced cross-matching tools allow the comparison of heterogeneous catalogs and data products.
Interactive analysis tools. Aladin provides intuitive tools for inspecting celestial coordinates, photometric properties, generating thumbnails, and supporting observational planning. Advanced features allow users to define observational fields, annotate regions of interest, and download data for subsequent analysis.
Support for Transient Events and Gravitational Waves
Aladin is a Virtual Observatory tool for the visualization and analysis of astrophysical transients, particularly those associated with gravitational-wave (GW) events. Thanks to its modular architecture and integration with IVOA standards, Aladin supports the rapid construction of complex workflows for scientific interpretation and observational planning.
Key functionalities
Area estimation within a credible region. Users can interactively analyze credible regions (e.g., 90% confidence level), computing their area in square degrees. This enables accurate assessment of localization uncertainty and facilitates comparison across different sky maps released by the LVK collaboration, whose localization precision typically improves through successive post-processing stages (e.g., from initial BAYESTAR to refined Bilby sky maps).
Querying and filtering galaxy catalogs. Aladin supports querying of major galaxy catalogs such as GLADE+, as well as user-defined datasets. Filtering can be applied based on astrophysical parameters (e.g., magnitude, redshift) to identify plausible electromagnetic counterparts.
Thumbnail view generator. The platform enables automatic generation of high-resolution thumbnail images of selected galaxies or regions of interest. These are useful for visual inspection, data validation, and preparation of observational campaigns, and can be exported for collaboration.
Building spatial and temporal credible regions. Using VO standards such as Space-Time MOC (ST-MOC), users can define credible regions that integrate both spatial localization and observational time windows. This is essential for targeting short-lived transient phenomena.
Spatial and temporal coverage intersections. Aladin allows users to intersect credible regions with observational footprints or survey coverage in both space and time. This functionality is critical for identifying optimal follow-up opportunities across multiple telescopes and observing facilities.
Aladin is a versatile and indispensable platform for both professional astronomers and educators. In the context of multi-messenger astronomy, it enables seamless visualization of gravitational-wave (GW) sky maps, the computation and analysis of credible regions, and the strategic planning of follow-up observations. These capabilities are enhanced by the integration of standardized tools such as Space-Time MOC (ST-MOC), which provides a formalism for encoding both spatial and temporal coverage in a unified framework.