With a bit of delay, we are now updating the status of the ALTO prototype project on our Blog.
On May the 25th our two water tanks were completely filled with water and the data taking started at 17:00 the same day. So now we are smoothly taking data since more than three weeks.
This picture shows the moment at which the second water tank was completely filled; the way for us to know that the water had reached the top of the tank was to open the upper tap and see when the water started to come out.
And here is a water-Cherenkov coincidence event (a coincidence event is an signal seen in both tanks at the same time and therefore it is generated by a cosmic ray induced atmospheric shower) seen by the photo-multipliers inside the ALTO tanks:
We already had some visits of the ALTO site on May the 31st, when 700 school kids visited the campus. They were of course all introduced to Astronomy and the ALTO project. 🙂