SDSS-IV

SDSS Fourteenth Data Release

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This post was written by Anne-Marie Weijmans, the SDSS Data Release Coordinator.

It’s the last day in July, and that means that it’s time again for a Sloan Digital Sky Survey (SDSS) data release! This year, we are very happy to announce our fourteenth public data release, DR14.

Making data publicly available is an important aspect of SDSS, as it allows SDSS data to be used world-wide by anyone with an internet connection. For more than a decade, SDSS data has been used by astronomers for their science, by teachers in their classrooms[1], by students for their school projects, and by the general public to learn more about the Universe. In order to have this broad impact, we work hard to not only make our data available, but to also ensure that it is accessible. All our data is thoroughly documented, and we have various tools, tutorials and examples to assist anyone interested in using our data — from professional astronomers to high school students. Just go to the SDSS data access website to find out how you can work with the SDSS data!

All the SDSS data are stored at the servers of the Center for High Performance Computing (CHPC), at the University of Utah. This particular server holds all the SDSS data releases, including DR14. Just DR14 alone is already a whopping 156 TeraBytes (TB = 1000 Gigabyte = 1012 bytes): that is more than 33,800 DVDs worth of data! Image credit: Adam Bolton

So, what is available in DR14?

  • APOGEE-2, or the APO Galaxy Evolution Experiment-2 is very proud to announce its first public data release! APOGEE-2 studies the structure of the Milky Way by taking infra-red spectra of stars, to learn more about how the Milky Way formed and evolved over time. You can explore these spectra using our webapp and find stellar parameters and chemical properties in the APOGEE-2 data release.
  • eBOSS, short for extended Baryon Oscillation Spectroscopic Survey, is also celebrating its first public data release! eBOSS is mapping the structure of the Universe, by taking optical spectra of distant galaxies and quasars. These spectra provide distance measurements to galaxies, quasars, and intervening gas, all of which enable eBOSS to make a 3D map of the Universe, and learn more about how galaxies cluster in space. Ultimately, eBOSS aims to precisely measure the expansion rate of the Universe, and reveal more about the nature of the mysterious Dark Energy that accelerates this expansion. The eBOSS spectra are also available in our webapp.
  • MaNGA or Mapping Nearby Galaxies at Apache Point Observatory already released its first data last year, but they’re back with even more data cubes, 2,812 in total! MaNGA uses integral-field spectroscopy to map the properties of galaxies, and find out more about how different galaxies form and evolve. The MaNGA team has prepared a very handy set of tutorials to explain the data cube format, so that anyone can make use of the wealth of information hidden in these galaxy integral-field spectra.

Finally, we’re also very excited to share our new Image Policy with you! We have updated our image license to a Creative Commons Attribution license (CC-BY), which means that any image on our website may now be downloaded, linked to, or otherwise used for any purpose, provided that the image credits are given.

We hope you’ll have fun with all the spectra, catalogs, and tools included in our Fourteenth Data Release, and that they will help you with your science, outreach, teaching, school projects, and anything else!

Anne-Marie Weijmans

SDSS Data Release Coordinator

University of St Andrews

[1] If you are a teacher, we invite you to check out our latest educational guides and activities at SDSS Voyages! We are also developing a Spanish version, available here.

Integral Field Spectroscopy 101

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As frequent readers know, the SDSS-IV-MaNGA survey plans to obtain spatially-resolved spectra of somewhere in the neighborhood of 10,000 galaxies using a technique called integral-field spectroscopy (or IFS). IFS essentially relies on placing an array of fiber-optic cables over an object of interest in the sky, and using the fiber-optics to pipe the light into a spectrograph, which produces the useful data by breaking up that light into its constituent wavelengths (an easy way you can do this at home is with a glass prism). The array of fibers is nicknamed a “bundle,” which is a pre-packaged grouping of fibers that we know the arrangement, and packaging the fibers allows more observational efficiency, since we don’t have to re-position the telescope to make a measurement of the same galaxy at a slightly different point.

However, the specific design of the fiber bundles is an important problem. Continue reading →

SDSS at #AAS225 – Tweets by SDSS-IV Spokesperson, Jennifer Johnson

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This week the SDSS Collaboration has a large presence at the American Astronomical Society‘s 225th Meeting, being held in Seattle, Washington.

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All sorts of SDSS related stuff will be going on at this meeting, from dozens of talks and posters, to demos of SDSS online resources at the SDSS Booth in the Exhibit Hall and not to mention the final data release from SDSS-III. Our “Tweep of the Week” for this exciting week will be SDSS-IV Spokesperson, Jennifer Johnson.

Jennifer Johnson is an Asssociate Professor in the Astronomy Department of The Ohio State University. Her science interests are in stellar abundances, the origin of the elements, nucleocosmochronology and the formation of our own Galaxy and Local Group. She is the Science Team Chair of the APOGEE survey of SDSS-III, and the Spokesperson for SDSS-IV (as well as working on APOGEE-2).

Jennifer Johnson

Jennifer Johnson

The SDSS Spokesperson has two main roles. She is the main person in charge of making sure the SDSS collaboration is running smoothly and fairly. As part of this, the Spokesperson Chairs the SDSS Collaboration Council (which has a representative from each institutional member of SDSS). This group are the first point of approval for requests for Architect Status (ie. people who have contributed so much to SDSS development they can request to be on any publication) and External Collaborator requests (non-SDSS members working on specific projects), as well as for drafting our publication and other collaboration policies. They also organise the annual SDSS Collaboration Meetings (the next one to be held in Madrid, 20-23rd July 2015).

The SDSS Spokesperson is also responsible for representing SDSS to the press and the public. As such she is responsible for working with the SDSS Communications Director (Jordan Raddick) to draft the text of press releases and maintain the SDSS website, as well as with the SDSS Director of EPO (Karen Masters) on our collective public engagement and outreach efforts.

Added: here’s a storify of Tweets by Jennifer during her week.