About

This site aims to provide accurate real time data and finder charts for the most interesting Solar System objects. Currently we are tracking 426 objects, including comets, planets, asteroids and spacecrafts.

Ephemeris

The ephemeris provided by this site (which include coordinates, distances from Earth and Sun, estimated magnitude and, for comets, time to perihelion) are obtained from the JPL Horizons service. In order to compute real time data, we are using interpolation of the Horizons sampled data, which provides a quite good accuracy. It you need very accurate and lates up-do-date data, please use the Horizons service directly.

Finder Charts and Catalogs

Our Finder Charts (see example) are created using the Digitized Sky Survey imagery. For each object, we acquire a 60'x40' DSS image in the red channel and we add overlays to represent the observed object, plus informative labels about the stars and deep sky objects represented in the chart. The position of the overlays is dynamic, this means that in case of fast moving objects (e.g. fast moving comets) it should be possible to see the live movement of the object on the chart.

We are using the following astronomical catalogs to show information about represented objects:

• Hipparcos Catalogue: contains information about 117934 bright stars. We use green labels for information from this catalogue
• Tycho 2 Catalogue: contains information about 2430468 stars. We use blue labels for information from this catalogue
• PGC 2003 Catalogue: contains information about 983261 galaxies. We use red labels for information from this catalogue
• GSC 2.3 Catalogue: an all-sky catalog of approximately 2 billion stars and galaxies containing positions, magnitudes,colors and proper motions complete to a minimum of V=18. We are using grey labels when showing information from this catalog

Acknowledgments

• The Digitized Sky Survey was produced at the Space Telescope Science Institute under U.S. Government grant NAG W-2166. The images of these surveys are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope. The plates were processed into the present compressed digital form with the permission of these institutions.
• The National Geographic Society - Palomar Observatory Sky Atlas (POSS-I) was made by the California Institute of Technology with grants from the National Geographic Society.
• The Second Palomar Observatory Sky Survey (POSS-II) was made by the California Institute of Technology with funds from the National Science Foundation, the National Aeronautics and Space Administration, the National Geographic Society, the Sloan Foundation, the Samuel Oschin Foundation, and the Eastman Kodak Corporation. The Oschin Schmidt Telescope is operated by the California Institute of Technology and Palomar Observatory.
• The UK Schmidt Telescope was operated by the Royal Observatory Edinburgh, with funding from the UK Science and Engineering Research Council (later the UK Particle Physics and Astronomy Research Council), until 1988 June, and thereafter by the Anglo-Australian Observatory. The blue plates of the southern Sky Atlas and its Equatorial Extension (together known as the SERC-J), the near-IR plates (SERC-I), as well as the Equatorial Red (ER), and the Second Epoch [red] Survey (SES) were all taken with the UK Schmidt telescope at the AAO.
• The Guide Star Catalogue–II is a joint project of the Space Telescope Science Institute and the Osservatorio Astronomico di Torino. Space Telescope Science Institute is operated by the Association of Universities for Research in Astronomy, for the National Aeronautics and Space Administration under contract NAS5-26555. The participation of the Osservatorio Astronomico di Torino is supported by the Italian Council for Research in Astronomy. Additional support is provided by European Southern Observatory, Space Telescope European Coordinating Facility, the International GEMINI project and the European Space Agency Astrophysics Division.
• The Guide Star Catalog-I was produced at the Space Telescope Science Institute under U.S. Government grant. These data are based on photographic data obtained using the Oschin Schmidt Telescope on Palomar Mountain and the UK Schmidt Telescope.

Comet Observation Data

• We acknowledge COBS, the Comet Observation Database for the usage of recent comet observation data, in particular the recently observed comet magnitude and coma diameter.

HTML5 Sky Maps and 3D orbit diagrams

• The constellation lines used in the ephemeris computation HTML5 sky charts have been created by Dan Burton as part of his Star Chart project.
• The HTML5 sky charts and orbit diagrams have been developed using the three.js javascript 3D library.
• The astronomy.js library by Don Cross is used to compute approximate position of the Solar System objects given their keplerian elements.

Images

• Images used in the Observing Guide are from: Tom Hall, Justin Flincher, Alvesgaspar via Wikimedia Commons
• The images used for the Moon phases in the Online Planetarium are derived from the original work by Jay Turner, licensed under Creative Commons Attribution-ShareAlike 4.0 International.
• The background image used in the 3D Solar System viewer is credited to ESO/S. Brunier.

Contacts

Please use one of the following ways to send any feedback for improvement, questions or suggestions:

• Write to:
• Use the Feedback Form

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