Archive for August, 2018

XXXth General Assembly of IAU – week 1

Posted August 26, 2018 By grigoris

The XXXth General Assembly of the IAU is held in Vienna, Austria, from Aug 20 to 31, 2018. The first week is finished now and tomorrow the second starts.

It is the biggest convention I have been so far with almost 3000 attendees, from all around the world literally. If I was to use only one world to describe it, ti would be “HUGE”! The Vienna International Center is great as it is neally easy to navigate and it can accommodate such an event. It is also very interesting and definitely uncommon to see exhibitors in astronomical conferences. You can find a large variety of booths from publishers, telescope/instrument companies, universities/telescopes/institutions advertising their projects, societies promoting their work, ESO and ESA, and an exhibition dedicated to the 100th anniversary of IAU. To all of these add the promotional stuff and gifts (from stickers to t-shirts and bags) and you get a rather different atmosphere sometimes.

A perspective of the exhibition.

A perspective of the exhibition.

The supernova - part of the 100th anniversary of the IAU.

The supernova – part of the 100th anniversary of the IAU.


LEGO models of some telescope facilities - part of the 100th anniversary of the IAU.

LEGO models of some telescope facilities – part of the 100th anniversary of the IAU.

Of course the main core is the various symposia and meetings. I came in Vienna on Tuesday (Aug 22) so as to take a look at the session on circumstellar environment around AGB stars (IAU Symposium 343: Why Galaxies Care About AGB Stars: A Continuing Challenge through Cosmic Time). Then, in the afternoon I went to the reception of the Focus Meeting 14: IAU’s role on global astronomy outreach, the latest challenges and bridging different communities, which was held at the Natural History Museum of Vienna. That was finally an amazing experience. Apart from getting to know fellow participants we got a free tour around the museum by its director. The museum exhibits an overwhelming collection, which represents only a small fraction of its collection (which is stored under the floors that are open to the public, and is accessible only to its scientists). On the next day (Thursday) the meeting took place, where I had an eposter representing the collective work we have done with the Hellenic Amateur Astronomy Association.

Then on Friday the Division G (Stars and Stellar Physics) Days, started, which I followed as much as possible, although I did tried to listen to other talks (the University of Vienna provided a very useful app to check the program and create your own agenda to easily follow whatever interests you most).

Another interesting week in starting tomorrow. I have a talk at the Division G Days and a poster contribution at the IAU Symposium 346: High-mass X-ray binaries: illuminating the passage from massive binaries to merging compact objects.

A fascinating comparison of what we knew in 1919 and in 2019 - Part of the 100th anniversary of the IAU.

A fascinating comparison of what we knew in 1919 and in 2019. It is amazing how our knowledge has advances. (Part of the 100th anniversary of the IAU.)

For a certain project I had created a number of photometric catalogs, each one corresponding to a specific observing field. I would like to construct the final (merged) one but for this I needed to add a unique source identifier at the beginning of each row. I decided to create a F#-**** tag for each source with “F#” corresponding to the field id and **** to a counter for each source per field. The final command was:

for i in {1,2,4,5,6,7,8,9,10,11,12,13,16};do echo F$i.matches.all.cat;awk -v id="$i" 'FNR>1 {print "F"id"-"1+c++, $0}' F$i.matches.all.cat >> results.tmp; done

So the command reads all the specific numbers for which a catalog with a filename of F*.matches.all.cat exists. The number of each field ($i) is parsed as an external variable (id) to awk which places it as the unique identifier “Fid-counter” with the incremental “counter” (1+c++) corresponding actually to the number of row (1+counter to begin from 1 instead of 0 – FNR avoids the first line of each catalog which is a column description). All results are written appended to the output file results.tmp (created automatically when non-existing).

Then, we can use sed to add the header:

sed -i '1i\#SourceID ...' results.tmp

An amazing drawing of Saturn

Posted August 2, 2018 By grigoris

In the era of imaging even from our cell phones making a drawing of a planet seems redundant. However, this is certainly a different perspective of a direct experience at the eyepiece of a telescope. And the final result can be fascinating, such as this drawing from Paul G. Abel, using the Clark telescope (a 24″ refractor) at Lowell observatory.

A drawing of Saturn using the 24" Clark refractor at Lowell observatory (Paul G. Abel).

A drawing of Saturn using the 24″ Clark refractor at Lowell observatory (Paul G. Abel).

Source: ALPO-Japan