Astronomy Visualization Metadata (AVM) is a standard for tagging digital astronomical images stored in formats such as JPEG, GIF, PNG and TIFF. [1] The AVM standard extends the concept of Extensible Metadata Platform (XMP) headers to include useful astronomical information about the subject of the image as well as the telescope used to take the image. This ensures that relevant information is transferred with the image when it is shared with others. AVM could be considered analogous to the FITS headers associated with raw astronomical data files.
JPEG is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality.
Portable Network Graphics is a raster-graphics file-format that supports lossless data compression. PNG was developed as an improved, non-patented replacement for Graphics Interchange Format (GIF).
The Extensible Metadata Platform (XMP) is an ISO standard, originally created by Adobe Systems Inc., for the creation, processing and interchange of standardized and custom metadata for digital documents and data sets.
The standard was proposed by the Virtual Astronomy Multimedia Project, part of the IAU Commission 55 and the International Virtual Observatory Alliance. It reached version 1.1 on May 14, 2008. [2] The standard is currently used to tag images from the Chandra X-ray Observatory, Herschel Space Observatory, Spitzer Space Telescope, ESA/Hubble and the European Southern Observatory. [3] Software packages such as PinpointWCS, [4] FITS Liberator [5] and Microsoft WorldWide Telescope have implemented the standard.
The International Virtual Observatory Alliance or IVOA is a worldwide scientific organisation formed in June 2002. Its mission is to facilitate international coordination and collaboration necessary for enabling global and integrated access to data gathered by astronomical observatories. An information system allowing such an access is called a Virtual Observatory. The main task of the organisation so far has focused on defining standards to ensure interoperability of the different virtual observatory projects already existing or in development.
The Chandra X-ray Observatory (CXO), previously known as the Advanced X-ray Astrophysics Facility (AXAF), is a Flagship-class space observatory launched on STS-93 by NASA on July 23, 1999. Chandra is sensitive to X-ray sources 100 times fainter than any previous X-ray telescope, enabled by the high angular resolution of its mirrors. Since the Earth's atmosphere absorbs the vast majority of X-rays, they are not detectable from Earth-based telescopes; therefore space-based telescopes are required to make these observations. Chandra is an Earth satellite in a 64-hour orbit, and its mission is ongoing as of 2019.
The Herschel Space Observatory was a space observatory built and operated by the European Space Agency (ESA). It was active from 2009 to 2013, and was the largest infrared telescope ever launched, carrying a 3.5-metre (11.5 ft) mirror and instruments sensitive to the far infrared and submillimetre wavebands (55–672 µm). Herschel was the fourth and final cornerstone mission in the Horizon 2000 programme, following SOHO/Cluster II, XMM-Newton and Rosetta. NASA is a partner in the Herschel mission, with US participants contributing to the mission; providing mission-enabling instrument technology and sponsoring the NASA Herschel Science Center (NHSC) at the Infrared Processing and Analysis Center and the Herschel Data Search at the Infrared Science Archive.
The metadata include information about the creator of the image, the content (including description and subject category), the method of observation (including facility, instrument and spectral information), the World Coordinate System (WCS) position in the sky, and the publisher of the image.
AVM was conceived by Robert Hurt, Lars Lindberg Christensen, and Adrienne Gauthier.
Lars Lindberg Christensen is science communicator and author of a dozen books on astronomy and science communication translated to ten languages. He is employed by ESO and by the International Astronomical Union. As press officer for the latter he was leading the media communication of the 2006 IAU reclassification of Pluto as a dwarf planet. He leads the Portal to the Universe project, and was the initiator of the ESA/ESO/NASA FITS Liberator project. He leads the Hubblecast and ESOcast video podcasts and initiated the Astronomy Visualization Metadata project, that later became the Virtual Astronomy Multimedia Project. He has received a handful of awards including the Danish Tycho Brahe Medal.
