DSS2

DSS2, short for Digitized Sky Survey 2, is a digital atlas of the night sky produced by digitizing photographic plates from major sky surveys. It is the successor to the original Digitized Sky Survey (DSS1) and provides broad, ready-to-use astronomical imagery that supports source identification, astrometric work, and cross-matching with newer surveys. DSS2 images are created from plates obtained with the Palomar Observatory Sky Survey II and the UK Schmidt Telescope, and the data are reprocessed to improve photometric calibration, astrometric accuracy, and image quality. The resulting products include blue and red photographic data and color composites, offering a convenient reference for researchers and educators.

Access and usage: DSS2 imagery is distributed by major astronomical data centers, including the Centre de Données astronomiques de Strasbourg (CDS). It is commonly accessed through virtual observatory tools such as the Aladin Sky Atlas, which allows users to view DSS2 data alongside other surveys and catalogs. The dataset has been widely employed for identifying astronomical objects, confirming variable sources, historical comparisons, and educational demonstrations due to its near-global coverage and archival value.

Limitations: Being derived from photographic plates collected decades ago, DSS2 has lower sensitivity and dynamic range compared with modern CCD-based surveys. Astrometry and photometry may require recalibration for precise measurements, and plate artifacts or defects can appear in some regions.

Other uses: The acronym DSS2 can also refer to Deep Space Station 2, a NASA Deep Space Network ground station used for communications with interplanetary missions. This article focuses on the astronomical DSS2, Digitized Sky Survey 2.