Posts with the Tag AG-Tagung:

• GAVO at the AG-Tagung in Garching

  2026-09-08 Markus Demleitner

  It's AG-Tagung time again: As every year in early autumn, the Astronomische Gesellschaft is beckoning the German astronomical Community. This year, 380 persons followed, which is a really good turnout by today's standards. Let's see how many we'll pull into to our booth: For the 19th time, GAVO is trying to get everyone there on board for using the Virtual Observatory – and contributing to it.

  We are in the huge building of the mechanical engineering department, and before everything started, we had our booth ready:

  

  To meet the challenge to fill this space with enthusiastic people, we again have a little VO-solvable riddle: this year's puzzler. At the booth, you can pick up what amounts to the full solution. Oh, and this year's prize is a towel sporting a photo of the recent total solar eclipse seen from the Ebro delta:

  

  Sorry, you can't participate remotely. But if you're in Garching: Be sure to pick up a problem sheet [Update: they're gone. But we'll happliy give you hand-drawn lots if you want] and hand in your guess. And drop by at our splinter meeting, too.

• GAVO at the AG-Tagung in Görlitz

  2025-09-16 Markus Demleitner

  Every year in early (meteorological) autumn, the venerable Astronomische Gesellschaft has its annual meeting, and since 2007, GAVO participates. This year's AG-Tagung takes place in Görlitz[1].

  As every year, we brought a Puzzler, and again you can win a beautiful towel with an astronomical image (this time: Euclid's view of the Cat's Eye nebula). To increase participation, this year we are doing multiple choice:

  

  (as PDF with complete instructions)

  In contrast to our puzzlers so far, this one is solvable with astronomical intuition alone, but of course the plan still is that you use the Virtual Observatory to work out the answer; on Thursday, I will tell you how right here in this post (and, of course, during the morning coffee break in Görlitz). As a special service to folks following us in the Fediverse, here are the complete hints towards this solution already.

  Normally, you would have to come to our booth to pick up these hints, one per coffee break; but somewhat regrettably our booth is not easy to find, and it is not staffed most of the time, either.

  

  Our long-runner, the lame excuses poster (on the poster wall right next to the door), is again eliciting amusement at our Görlitz booth.

  The background is that the venue in Görlitz is rather exotic: The plenaries take place in the (desecrated) old synagoge of Görlitz[2], and the exhibitors were placed in the „Sängerempore“, the singers' gallery (mainly because of fire code constraints, I'm told). Of course, the singer's gallery was designed so any sound in it carries to the main room, and that means that during the sessions, it needs to be silent up there. Hence, we don't do our traditional informal side meetings there, and there is none of my beloved VO show-and-tell either.

  In the afternoon, splinter sessions are distributed over a significant part of the old town, and thus few people are near the synagoge in the first place. “Our” session, the one on E-Science and Machine Learning, took place at Schlesisches Museum, for instance. There, I reported on our experiences with our VO course and invited people to run one of these, too. My gut feeling at the end of the talk was that I will not hold my breath until the next full-semester VO course in presence takes place at a German university. But then perhaps a joint course, held online, is more realistic?

  

  The plenaries are taking place below the exquisitely decorated dome of the old Görlitz synagogue.

  The reason for the somewhat haphazard room situation is actually rather exciting: The institution hosting the conference does not really exist yet, in the sense that it does not have a large lecture hall and mainly exists a a suite of leased offices. It's the DZA (previously mentioned here), a future large (~1000 employees) astronomical institute to be built here in Görlitz. Given its existence in statu nascendi, I am rather impressed how well things work.

  Later this year, by the way, I will be in a similar situation, as I am part of the LOC of the 2025 IVOA Interop. I sincerely hope things will work about as smooth then as they do now.

  Followup (2025-09-18)

  This year's winner of the puzzler prize will be well known to many of you:

  

  I have also published the solution and updated the puzzlerweb accordingly.

  While polishing the solution, I noticed I should be advertising TOPCAT's ability to plot spherical geometries like polygons. So, the solution does that, and in a lame attempt to make you look, here's the image I came up with within a few seconds:

  

  [1]

  Since last year's meeting was in Köln, you could suspect that we only meet in towns with ö. But no, the AG does not pick host cities by röck döts. Next year's meeting will not be in Göttingen, Würzburg, München, Günzburg, or Gräfenberg. It will be in Garching. Except… That town's official name happens to be Garching bei München. Oh my. Note that the conference language still is English, in case you are tempted to drop by.

  [2]

  The reason it is still there, by the way is rather simple: In 1938, when many Germans torched their neighbours' synagogues, in most cities the fire brigade basically stood by and at best made sure the fires did not spread. In Görlitz, they actually put the fire out. Which goes to show that the others could have done that as well. They just did not want to.

• GAVO at the AG-Tagung in Köln

  2024-09-09 Markus Demleitner

  

  As every year, GAVO participates in the fall meeting of the Astronomische Gesellschaft (AG), the association of astronomers working in Germany. This year, the meeting is hosted by the Universität zu Köln (a.k.a. University of Cologne), and I want to start with thanking them and the AG staff for placing our traditional booth smack next to a coffee break table. I anticipate with glee our opportunities to run our pitches on how much everyone is missing out if they're not doing VO while people are queueing up for coffee. Excellent.

  As every year, we are co-conveners for a splinter meeting on e-science the virtual observatory, where I will be giving a talk on global dataset discovery (you heard it here first; lecture notes for the talk) late on Thursday afternoon.

  And as every year, there is a puzzler, a little problem rather easily solvable using VO tools; I was delighted to see people apparently already waiting for it when I handed out the problem sheet during the welcome reception tonight. You are very welcome to try your hand on it, but you only get to enter our raffle if you are on site. This year, the prize is a towel (of course) featuring a great image from ESA's Mars Express mission, where Phobos floats in front of Mars' limb:

  

  I will update this post with the hints we are going to give out during the coffee breaks tomorrow and on Wednesday. And I will post our solution here late on Thursday.

  At our booth, you will also find various propaganda material, mostly covering matters I have mentioned here before; for posteriority and remoteriority, let me link to PDFs of the flyers/posters I have made for this meeting (with re-usabilty in mind). To advertise the new VO lectures, I am asking Have you ever wished there was a proper introduction to using the Virtual Observatory? with lots of cool DOIs and perhaps less-cool QR codes. Another flyer trying to gain street cred with QR codes is the Follow us flyer advertising our Fediverse presence. We also still show a pitch for publishing with us and hand out the inevitable who we are flyer (which, I'll readily admit, has never been an easy sell).

  

  Bonferroni for Open Data?

  A lot more feedback than on the QR code-heavy posters I got on a real classic that I have shown at many AG meetings since the 2013 Tübingen meeting: Lame excuses for not publishing data.

  A tricky piece of feedback on that was an excuse that may actually be a (marginally) valid criticism of open data in general. You see, in particular in astroparticle physics (where folks are usually particularly uptight with their data), people run elaborate statistics on their results, inspired by the sort of statistics they do in high energy physics (“this is a 5-sigma detection of the Higgs particle”). When you do this kind of thing, you do run into a problem when people run new “tests” against your data because of the way test theory works. If you are actually talking about significance levels, you would have to apply Bonferroni corrections (or worse) when you do new tests on old data.

  This is actually at least not untrue. If you do not account for the slight abuse of data and tests of this sort, the usual interpretation of the significance level – more or less the probablity that you will reject a true null hypothesis and thus claim a spurious result – breaks down, and you can no longer claim things like “aw, at my significance level of 0.05, I'll do spurious claims only one out of twenty times tops”.

  Is this something people opening their data would need to worry about when they do their original analysis? It seems obvious to me that that's not the case and it would actually be impossible to do, in particular given that there is no way to predict what people will do in the future. But then there are many non-obvious results in statistics going against at least my gut feelings.

  Mind you, this definitely does not apply to most astronomical research and data re-use I have seen. But the point did make me wonder whether we may actually need some more elaborate test theory for re-used open data. If you know about anything like that: please do let me know.

  Followup (2024-09-10)

  The first hint is out. It's “Try TOPCAT's TAP client to solve this puzzler; you may want to took for 2MASS XSC there.“ Oh, and we noticed that the problem was stated rather awkwardly in the original puzzler, which is why we have issued an erratum. The online version is fixed, it now says “where we define obscure as covered by a circle of four J-magnitude half-light radii around an extended object”.

  Followup (2024-09-10)

  After our first splinter – with lively discussions on the concept and viability of the “science-ready data” we have always had in mind as the primary sort of thing you would discover in the VO –, I have revealed the second hint: “TOPCAT's Examples button is always a good idea, in particular if you are not too proficient in ADQL. What you would need here is known as a Cone Selection.”

  Oh, in case you are curious where the discussion on the science-ready data gyrated to: Well, while the plan for supplying data usable without having to have reduction pipelines in place is a good one. However, there undoubtedly are cases in which transparent provenance and the ability to do one's own re-reductions enable important science. With datalink [I am linking to a 2015 poster on that written by me; don't read that spec just for fun], we have an important ingredient for that. But I give you that in particular the preservation of the software that makes up reduction pipelines is a hard problem. It may even be an impossible problem if “preservation” is supposed to encompass malleability and fixability.

  Followup (2024-09-11)

  I've given the last two hints today: “To find the column with the J half-light radius, it pays to sort the columns in the Columns tab in TOPCAT by name or, for experts using VizieR's version of the XSC, by UCD.” and “ADQL has aggregate functions, which let you avoid downloading a lot of data when all you need are summary properties. This may not matter with what little data you would transfer here, but still: use server-side SUM.”

  Followup (2024-09-12)

  I have published the (to me, physically surprising) puzzler solution to https://www.g-vo.org/puzzlerweb/puzzler2024-solution.pdf. In case it matters to you: The towel went to Marburg again. Congratulations to the winner!

  Followup (2024-09-13)

  On the way home I notice this might be a suitable place to say how I did the QR codes I was joking about above. Basis: The embedding documents are written in LaTeX, and I'm using make to build them. To include a QR code, I am writing something like:

  \includegraphics[height=5cm]{vo-qr.png}}
  

  in the LaTeX source, and I am declaring a dependency on that file in the makefile:

  fluggi.pdf: fluggi.tex vo-qr.png <and possibly more images>
  

  Of course, this will error out because there is no file vo-qr.png at that point. The plan is to programatically generate it from a file containing the URL (or whatever you want to put into the QR code), named, in this case, vo.url (that is, whatever is in front of -qr.png in the image name). In this case, this has:

  https://doi.org/10.21938/avVAxDlGOiu0Byv7NOZCsQ
  

  The automatic image generation then is effected by a pattern rule in the makefile:

  %-qr.png: %.url
          python qrmake.py $<
  

  And then all it takes is a short script qrmake.py, which based on python3-qrcode:

  import sys
  import qrcode
  
  with open(sys.argv[1], "rb") as f:
          content = f.read().strip()
  output_code = qrcode.QRCode(border=0)
  output_code.add_data(content)
  
  dest_name = sys.argv[1].replace(".url", "")+"-qr.png"
  output_code.make_image().save(dest_name)
  

• GAVO at the AG-Tagung in Berlin

  2023-09-12 Markus Demleitner

  

  It's time again for the annual meeting of the German astronomical society, the Astronomische Gesellschaft. Since we have been reaching out to the community at these meetings there since 2007, there is even a tag for our contributions there on this blog: AG-Tagung.

  Due to fire codes, our traditional booth would almost have ended up in a remote location on the third floor of TU Berlin's main building, and I had already printed desperate pleas to come and try find us. But in a last minute stunt, the local organisers housed us in an almost perfect place (thanks!): we're sitting right near the entrance, where we can rope in passers-by and then convince them they're missing out if they're not “doing VO”.

  One opportunity for them to realise how they're missing out is our puzzler, this year about a lonely O star:

  

  Since this star must have formed very (by astronomical standards) recently, it should still be in its nursery, something like a nebula – but it clearly is not. It's a runaway. But from what?

  Contrary to last year, we will not accept remote entries, sorry – but you're welcome to still try your hand even if you are not in Berlin. Also, if you like the format, there's quite a few puzzlers from previous years to play with.

  I have just (11:30) revealed the first hint towards our sample solution:

  We recommend solving this puzzler using Aladin. There, you can look for services serving, e.g., the Gaia DR3 data in the little “select” box in in the lower left corner. Shameless plug: Try dr3lite.

  If you are on-site: drop by our booth. If not: we will post updates – in particular on the puzzler – here.

  Followup (2023-09-13)

  At yesterday's afternoon coffee break, we gave the following additional hint:

  To plot proper motions for catalogue objects in Aladin, try the Create a filter… entry in the Catalog menu.

  And this morning, we added:

  If you found Gaia DR3, you can also find editions of the NGC catalog (shameless plug: openngc). These are small enough for a plain SELECT * FROM….

  Followup (2023-09-14)

  The last puzzler hint is:

  Aladin's dist tool comes in handy when you want to do quick measurements on the sky. If you are in Berlin, you still have until 16:00 today to hand in your solution.

  However, the puzzler should not prevent you from attending our splinter meeting on e-science and the Virtual Observatory, where I will give an overview over the state of ADQLs in arrays. Regular readers of this blog will remember my previous treatment of the topic, but this time the queries will be about time series.

  Followup (2023-09-14)

  Well, the prize is drawn. This time, it went to a team from Marburg:

  

  As promised, here's our solution using Aladin. But one of the nice things about the VO is that you get to choose your tools. One participant using pyVO was kind enough to let us publish their solution using pyVO, too: puzzler2023-solution.py. Thanks to everyone who particpated!

• We are at the AG-Tagung in Bremen

  2022-09-13 Markus Demleitner

  

  Our puzzler prize for this year (well, its lower part): The Hertzsprung-Russell diagram according to Gaia on a wonderfully soft towel.

  After two years of “virtual” meetings, this year the venerable “Herbsttagung der Astronomischen Gesellschaft”, the meeting of Germany's Astronomical Society, is back. Almost as before Corona, it is bringing astronomers together, this year in Bremen (previously on this blog: 2018 in Stuttgart).

  Bowing to the “German“ in GAVO, this is an opportunity for us to connect to the (or, rather, our) community, both with a splinter meeting and with our traditional booth, at which you can pick up various edifying printed matter, a laminated ADQL reference card, and lots of VO wisdom (i.e., chat with our friendly booth staff).

  And you can solve our puzzler, a little problem that has an elegant VO-based solution (previous puzzlers). As is tradition, solving the puzzler will not only give you intellectual satisfaction and perhaps even insights into the VO, it will also give you a chance to win an item that is heavenly fluffy. The article photo shows this year's puzzler prize, and if this piques your desire, absolutely feel free to hand in solutions even if you are not in Bremen[1].

  Update 2022-09-15: This year's prize went to Bonn. So, there's no point to hand in solutions any more – rather, have a look at how we thought the problem should be approached.

  [1]	We've had an actual award (the AG-RAS Carolin Herschel medal) being handed out virtually yesterday, so in case we really draw a remote entry, I am very confident that we can work something out for handing over the prize.

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