PPMXL+Gaia DR1=HSOY in the Heidelberg Data Center

The stunning precision of Gaia’s astrometry is already apparent in the first release of the data obtained by the satellite, available since last September. However, apart from the small TGAS subset (objects already observed by the 90ies HIPPARCOS astrometry satellite) there is no information on the objects’ proper motions in DR1.

Until Gaia-quality proper motions will become available in DR2, the HSOY catalog – described in Altmann et al’s paper Hot Stuff for One Year (HSOY) freshly up in arXiv and online at http://dc.g-vo.org/hsoy – can help if you can live with somewhat lesser-quality kinematics.

It derives proper motions for roughly half a billion stars from PPMXL and Gaia DR1, which already gives an unprecedented source for 4D astrometry around J2015. And you can start working with it right now. The catalog is available in GAVO’s Heidelberg data center (TAP access URL: http://dc.g-vo.org/tap; there’s also an SCS service). Fire up your favourite TAP or SCS client (our preference: TOPCAT) and search for HSOY.

Image: Errors in proper motion in declination in HSOY on the sky

HSOY average errors in proper motion in declination over the sky, in mas/yr. The higher errors south of -30 degrees are because the great sky surveys of the 50ies could not be extended to the southern sky, and thus the first epoch there typically is in the 1980ies.

Oh, and in case you’re new to the whole TAP/ADQL game: There’s our ADQL introduction, and if you’re at a German astronomical institution, we’d be happy to hold one of our VO Days at your institute – just drop us a mail.

DaCHS, SODA, and Datalink

DaCHS, the Data Center Helper Suite, is a comprehensive suite for publishing astronomical data to the Virtual Observatory, supporting most major protocols out there. On Dec 12, GAVO released a new version, 0.9.8. The most notable change is that now SODA is supported as specified in the last IVOA Proposed Recommendation.

This is fairly big news, as SODA is the VO’s answer to providing cutout services and the like, which obviously is important part with datasets in the Multi-Gigabyte range and the VO’s wider programme of trying to enable users to only download what they need. But even for spectra, which aren’t typically terribly large, we have been using SODA; for instance, when you just want to see the development of a single line over time, say,, it’s nice to not have to bother with the the full spectrum. The spectral client SPLAT has been offering such functionality for a couple of year now — watch out for the scissors icon in discovery results. These indicate SODA support on the respective services.

Another client that will support SODA and its basis Datalink is Aladin – we’ve seen a promising demo of that during the last Interop in Trieste. Until the clients are there, DaCHS contains a (largely re-usable) stylesheet that generates simple UIs for Datalink documents and SODA services. Some examples:

Note again that all of these are not actually web pages, they’re machine-readable metadata collections; if you don’t believe it, pull the URLs with curl. To learn more about the combo of Datalink and SODA, check out this ADASS 2015 poster (preferably before even looking at the not terribly readable standards texts).

If you’re running DaCHS yourself and can’t wait to run Datalink and SODA — here’s how to do that.

ProvenanceDM Working Draft released

We’ve released the first version of working draft for the IVOA Provenance Data Model at the IVOA documents page:

ProvenanceDM Working draft.

Updated versions will be put at the same URL (check the date! The first version is from 21st November 2016).

Want to get your hands on the very latest version?
Check out the volute svn repository! Since it’s not so easy to find what you want there, here’s the path to the Provenance Data Model at volute, and here’s a direct link to the latest development draft [pdf].

We’re happy to receive some feedback on the document via IVOA’s data modelling mailing list dm@ivoa.net.

UWS 1.1 approved!

UWS stands for Universal Worker Service and is an IVOA standard provides a protocol which can be used for accessing databases and other web services from the command line, e.g. using the python uws-client.
This allows to create (asynchronous) jobs for a web service (e.g. an SQL query), check their status, retrieve their results, abort or delete them.

The updated version 1.1 was approved at the InterOperability Meeting last week and brings some nice new features:

  • Job list filtering: When retrieving the job list, one can now retrieve only jobs created after a certain date, the latest n jobs or jobs with a certain phase (e.g. EXECUTING or COMPLETED)
  • WAIT: When asking for job details, it is now possible to append a WAIT parameter and provide an integer as wait-time in seconds. This means that the job details will only be returned when the wait-time is over or the job’s phase has changed, whichever comes first.

For all the details, have a look at the standard itself:
UWS 1.1 Recommendation.

A few examples using the CosmoSim database are given here:
UWS tutorial for CosmoSim (pdf), using 1.0 and
UWS 1.1 update at CosmoSim.

And if you want to implement UWS 1.1 for your own service, here is a test-tool that may be useful for validating for you for validating the new features:
uws-validator.

ADASS and InterOp participation

We were taking part at this year’s ADASS meeting (Astronomical Data Analysis Software and Systems) in Trieste and contributed a talk on the Provenance Data Model for the data model session.

The ADASS meeting was followed by the Northern Fall Interoperability Meeting of the IVOA, where new standards and protocols were being discussed.

It was a quite long week, but very inspiring!!