• GAVO at AG-Tagung 2017, Göttingen

  2017-09-19 Markus Demleitner

  

  For the 11th time, GAVO has a booth at a meeting of the venerable Astronomische Gesellschaft (AG). This year, we are in Göttingen, again offering advice to users and data providers at our booth (if you're looking for us: We're close to the entrance of Hörsaal 5).

  And again we have a Puzzler, a little problem easily solved if you know your VO tech – and if you don't we'll gladly help you at our booth. We are also giving hints there, one being released at each coffee break on Tuesday and Wednesday (there are little posters with them, too, if you miss one). Of course, if you're not in Göttingen, you're still welcome to try your hand. You won't get to win our great first prize then, the big Crab Nebula towel (it should be easy to spot on the image above).

  If, on the other hand, you are in Göttingen, be sure to drop by our splinter meeting. Yours truly, for instance, will speak about EPN-TAP (remember And the Solar System, too right here? That's what this is about).

  Update 2017-09-20, 17:00 We've just given out the last hint for the puzzler, and so we can publish them all over on the puzzler archive: Hints for the 2017 puzzler. If you're in Göttingen, you still have until tomorrow 16:00 to hand in a solution and perhaps win our nice and fuzzy Crab Nebula towel.

  Update 2017-09-21, 17:00 And the winner is... again not from Marburg, which is beginning to become a running gag, and they've been unlucky for the last three years in a row. Anyway, here's our proposed solution.

  

• The Earth is Our Telescope

  2017-07-31 Markus Demleitner

  

  The coverage of the 2007-2012 Antares neutrinos, with positional uncertainties scaled by three.

  At our Heidelberg data center, we have have already published some neutrino data, for instance the Amanda-II neutrino candiates, the IceCube-40 neutrino candidates, and the 2007-2010 Antares results.

  That latter project has now given us updated data, for the first time including timestamps, available as the Antares service.

  Now, if you look at the coverage (above), you'll notice at least two things: For one, there's no data around the north pole. That's because the instrument sits beyond the waters of the Mediterranean sea, not far from where some of you may now enjoy your vacation. And it is using the Earth as its filter – it's measuring particles as they come ”up” and discards anything that goes “down”. Yes, neutrinos are strange beasts.

  The second somewhat unusual thing is that the positional uncertainties are huge compared to what we're used to from optical catalogs: a degree is not uncommon (we've scaled the error circles by a factor of 3 in the image above, though). And that requires some extra care when working with the data.

  In our table, we have a column origin_est that actually contains circles. Hence, to find images of the “strongest” neutrinos in our obscore table, you could write:

  SELECT * FROM
  ivoa.obscore AS o
  JOIN (
    SELECT top 10 * FROM antares.data
    ORDER BY n_hits desc
  ) AS n
  ON 1=INTERSECTS(
    s_region,
    origin_est)
  

  in a query to our TAP service.

  But of course, this only gets really exciting when you can hope that perhaps that neutrino was emitted by some violent event that may have been observed serendipitously by someone else. That query then is (and we're using all the neutrinos now):

  SELECT * FROM
  ivoa.obscore AS o
  JOIN antares.data as n
  ON
     epoch_mjd between t_min-0.01 and t_max+0.01
    AND
      dataproduct_type='image'
    AND
      1=INTERSECTS(origin_est, s_region)
  

  On our data center, this doesn't yield anything at the moment (it does, though, if you do away with the spatial constraint, which frankly suprised me a bit). But then if you went and ran this query against obscore services of active observatories? And perhaps had your computer try and figure out whether anything unusual is seen on whatever you find?

  We think that would be really nifty, and right after we've published a first version of our little pyVO course (which is a bit on the back burner, but watch this space), we'll probably work that out as a proper pyVO use case.

  And meanwhile: In case you'll be standing on the shores of the Mediterranean this summer, enjoy the view and think of the monster deep down in there waiting for neutrinos to detect – and eventually drop into our data center.

• DaCHS 1.0 released

  2017-07-11 Markus Demleitner

  Today, I have released DaCHS 1.0 – after long years in the 0.9 range, it was finally time to do so. The jump in the major version number was an opportunity to remove some cruft that had accumulated over the years; this, on the other hand, means that if you're running DaCHS, you should watch the upgrade and see if anything broke later (this might be the perfect time to add regression tests to your RDs).

  The changelog is below, but before that a bold-faced warning:

  Install python-astropy before upgrading

  This is because DaCHS now depends on astropy rather than pyfits and pywcs. The latter is no longer part of Debian stretch, and so we made the jump to astropy (that would have been due during Debian stretch's lifetime anyway) even before 1.0.

  Now, Debian holds back packages with new dependencies, and due to the way DaCHS' modules are distributed, DaCHS will break when some of its packages are held back. The symptom is error messages like "pkg_resources.DistributionNotFound: gavodachs==0.9.8". If you already see those, a apt-get dist-upgrade should get you in business again.

  With this out of the way, here is an annotated log of the major changes:

  • DaCHS' main entry point is now actually called dachs (i.e., call dachs imp q and such in the future). gavo will work as an alias for quite a while to come, though, and it's still used a lot in the documentation (you're welcome to fix this: the docs are maintained on github).
  • Hopefully more useful manpage (of course, also available with man dachs) – have a peek!
  • UWS support is now at version 1.1 (i.e., there's creationDate in jobs, filters in the joblist, and slow polling).
  • Added “declarative” licenses. Please read the Licensing chapter in the tutorial and slap licenses on your data.
  • Now using astropy.wcs instead of pywcs, and astropy.io.fits instead of pyfits. The respective APIs have, unfortunately, changed quite a bit. If you're using them (e.g., in processors), you'll have to change your code; it's unlikely services are impacted at runtime. (see also How do I update my code?).

  • Removed the //epntap#table-2_0mixin. Use

    //epntap2#table-2_0 instead (sorry).

  • Removed sdmCore (use Datalink/SODA instead); the SODA procs in //datalink are also gone, use the ones from //soda instead (sorry, SODA development has been difficult on the IVOA level).
  • Removed imp -u flag and the corresponding updateMode parse option. If you used that or the uploadCore, just mark the DDs involved with updating="True" instead.
  • Massive sanitation of input parameter processing. If you've been using inputTable, inputDD, or have been doing creative things with inputKeys, please check the respective services carefully after upgrading. See also DaCHS' Service Interface in the reference documentation. The most user-visible change in this department is if you've been using repeated parameters to fill array-valued inputs. That's no longer allowed; if you actually must have this kind of thing, you'll need a custom core and must fill the arrays by hand.
  • In DaCHS' SQL interface, tuples now are matched to records and lists to arrays (it was the other way round before). If while importing you manually created tuples to fill to array-like columns, you'll have to make lists from these now.
  • rsc.makeData or rsc.TableForDef no longer automatically make connections when used on database tables. You must give them explicit connection arguments now (with base.getTableConn() as conn:).
  • logo_tiny.png and logo_big.png are now ignored by DaCHS, all logos spit out by it are now based on logo_medium.png, including, if not overridden, the favicon (that you will now get if you have not set it before).
  • Removed (probably largely unused) features editCore, SDM2 support, pkg_resource overrides, simpleView, computedCore.
  • Removed the argparse module shipped with DaCHS. This breaks compatibility with python 2.6 (although you can still run DaCHS with a manually installed argparse.py in 2.6).

  Even though that's quite a mouthful, I expect few people will actually experience breaking services. If you do, by all means let us know on the DaCHS-support mailing list.

  As usual, the general upgrading instructions are available in the operator's guide; if you plan on upgrading to stretch soon, also have a look at hints on postgres upgrades. Stretch comes with postgres 9.6 (jessie: 9.4), and you should migrate sooner or later anyway.

  Users not using Debian's package management can, as usual, grab tarballs from http://soft.g-vo.org/dachs.

• ADQL tricks at MPIA

  2017-06-29 Markus Demleitner

  

  The 2017-06-29 ADQL talk (red circle) from 30000 ft

  Today I was up on Heidelberg's signature mountain, Königstuhl, at the Max-Planck-Institute for Astronomy for a little talk on what I'd provisionally call “intermediate ADQL” – discussing some aspects of ADQL and some TAP techniques that may not be immediately obvious but still generally and straightforwardly applicable to everyday problems. Since I suspect the lecture notes for that talk may be of interest to some readers of this blog, I thought I should share them here.

  What this also contains is a very quick piece of pyVO-based python (which needs both this helper and a recent pyVO) for a use case that comes up fairly often: “Give me all proper motions (radio fluxes, distances, radial velocities, whatever) for object in this region.”

  This uses a discovery case I've been after for quite a while now: Find services by the UCDs of tables within them. And while that's been possible for quite a while on GAVO's Registry UI WIRR, there's still too many services that don't declare their tables to the Registry, and when talking about TAP, the situation is still a bit worse (as has been mentioned in my account of the last interop). So – enjoy the code, but very frankly, you'll still see wires sticking out for a several months yet.

  And if you run a TAP service yourself, please have a look at how to enable table discovery over on the IVOA wiki so we can finally get those pesky wires out of our users' eyes.

• GAVO at the Northern Spring Interop

  2017-05-29 Markus Demleitner

  

  15 Years of IVOA: The birthday cake our Shanghai hosts prepared for us.

  Every half year, VO enthusiasts from all over the world gather for an “Interoperability conference”, or Interop for short. The latest such event, the Shanghai Interop 2017, ended Friday a week ago. It has been a “long” one again after the short southern spring Interop in Trieste last year (featured in this blog).

  As usual, it was a week of many discussions and much consensus-building. In this post, I'd like to mention a few of the GAVO-related contributions; links typcially go to slides or lecture notes PDFs.

  On the Registry side of things, we're currently (among many other things) briding the gap between DOIs and the Registry in VOResource 1.1, and we invited registry providers to take up the new features, as well as proposing how to update RegTAP (which is used to actually query the Registry) to cope with the new metadata.

  Also in Registry, our efforts of almost a decade to properly support registering tables and similar data collections bore fruit (Britain's Mark Taylor reported on his experiences taking up our current proposal), and the fairly spectacular new Aladin V10 (presented by the CDS' Pierre Fernique, who showed off what I'm tempted to call a “visual registry interface”) urgently needs what we've developed over the years.

  We furthermore reported on new steps to finally let people search the registry using Space-Time constraints (spoiler: the tech is almost there, registry records need lots of work).

  Spatial searches in the registries are one thing enabled by storing and searching for MOCs in relational databases, as was reported by Markus Nullmeier over in an Applications session. The setting may already tell you that these MOCs (Multi Order Coverages, a healpix-based way of representing fairly arbitrary areas on the sky) have applications far beyond Registry.

  Also in Apps, Ole reported on progress in packaging VO applications for easy and reliable installation, in this case for Debian and derivatives. Finally for Apps, Margarida reported on getting lines and line lists into the spectral analysis package SPLAT: Implementation of SLAP and VAMDC interfaces in SPLAT-VO.

  In the wider area of data access protocols and underlying data models, we contributed to Marco's talk on the long-overdue facelifting for the VO's bedrock, Simple Cone Search (Keeping SCS up-to-date within DAL landscape) – the fact that there's an installed base of 15000 of such services may let you guess that we need to tread lightly here. On the bleeding-edge side of things, we presented our current ideas on how, eventually, several data models, data modelling as such and the annotation of data according to these data models might play together in publishing time domain data with DACHS (previously featured on this blog in a slightly less technical way).

  We also talked about education and outreach. Hendrik reported on our ADQL course and how it helps future astronomers learn dealing efficiently with even very large datasets. Hendrik's long-lasting dedication to these topics did not go unpunished at this interop: since the Exec meeting on the Interop Wednesday he is vice-chairing the education interest group of the IVOA. Back in the session I also mused a bit about what metadata changes are needed to make the VO tutorial collection VOTT more useful.

  It is a particular pleasure for me to mention that the IVOA has a new interest group: “Solar System”. Regular readers of the blog will have noticed that I have a particularly soft spot in my heart for that crowd, and so I gave a short overview over how DaCHS is used among them, too.

  And that's just the official programme. Much more fixing, designing, and discussion went on between sessions or in the evenings. The latter, of course, included some decidedly less technical aspects. Including, as pictured above, a nice birthday cake for the IVOA, as it is now 15 year since the first Interop meeting in January 2002.

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