Category Archives: Projects

7 years of PVOL

The Planetary Virtual Observatory and Laboratory (PVOL) is an online database of amateur images of the outer planets (Jupiter, Saturn, Uranus and Neptune). It was developed in early September 2004, during my attendance to the first NVO Summer School in Aspen (Co, USA). It was first put online during November 2004, so we already celebrated its 7th birthday.

After a bit more than 7 years online, it was time to prepare some charts showing the evolution in the number of images published. The following graph shows the number of images of Jupiter available since year 2000 (PVOL inherited the images already available in the previous IOPW page).

And the 2011-2012 apparition of Jupiter didn’t even finish yet!

So, thanks to the growing community of amateur astronomers (260 listed today) publishing images in the PVOL, and special thanks to the Planetary Sciences Group of the UPV-EHU for the great work they’re doing managing the system.

PVOL in the AstronomíA magazine

I started writing the PVOL (Planetary Virtual Observatory and Laboratory) system during the first NVO Summer School which took place in Aspen (Colorado, USA) in the summer of 2004. The system is up and running since November 2004 in the Ajax Cluster of the Planetary Sciences Group, in the University of the Basque Country, and available at


We currently have more than 200 registered contributors (50 of them allowed to directly publish new images), more than 9200 images of Jupiter (first one from year 2000) and more than 1800 images of Saturn. Last image received was just from yesterday:

Good news is that not only amateur observers are publishing lots of new images of Giant Planets every day (mainly Jupiter and Saturn), but also that two of the guys in the Planetary Sciences Group also wrote an article about the PVOL system and how it helps on the research of the atmospheres of these planets. The publication is not available online, it seems, so if you want to take a look at it you’ll need to buy the magazine (Spanish only):

Pequeños telescopios al estudio de los planetas gigantes“, por Jon Legarreta y Ricardo Hueso, AstronomíA, November 2010.

The Octopus Library 0.0.1 released

LGPLv3 logo

This is the first version of the Octopus Library, a C library providing advanced file system crawling and monitoring capabilities on top of GLib’s GIO. This library, released under the LGPLv3+, is a full rewrite of some of the features provided by Gnome Tracker‘s libtracker-miner library.

Online documentation is available in:

The sources can be downloaded from:

The mdsum is:
cca4e5152e9586abc57d330bad7bee09 octopus-0.0.1.tar.gz

This release is also GPG signed. You can download the signature from:

Some of the features provided by this new library are:
* Recursive crawling on a set of configured directories. For example, it may be configured to recursively crawl /home and /media.
* Directories inside the tree to recurse can be set to be ignored. For example, it may be configured to recursively crawl /home/user but not /home/user/.private.
* Directories may be configured to be crawled, but not recursively. For example, /home may be configured to be non-recursively crawled.
* Any possible combination of crawled, recursively-crawled and ignored is supported, as long as the same path is not added with different options.
* For every file or directory found during the crawling operation, a new event will be notified to configured signal listeners.
* During the filesystem crawling, monitors may be enabled in directories.
* Event merging; so that multiple events of the same type on the same file are all combined in a single event. Event merging will also act on different event types, trying to combine them in the best possible way. For example, if a file is CREATED, UPDATED and then REMOVED no event will be notified.
* Real-Time event notification. Both merged or raw events can be set to be notified in real-time.
* On-Demand iteration of events. If enabled, the monitor will store all received events in a proper order, so that afterwards they can be iterated. You could for example, configure a timeout every 30 minutes to iterate all raw or merged events which happened since the last iteration.
* Proper order of events. When notifying or iterating events the order may not be exactly the same as the one in the original events, but it is assured that if followed all events in the order given by the Octopus Monitor, the result is exactly the same as if followed in the original order.

In the roadmap for next versions:
* Asynchronous API will be available in release 0.0.2.
* A ‘database’ of already crawled directories will be optional, storing mtimes of each found file, so that when the program starts and re-crawls a common directory structure, it will check if the files in the tree changed since the last time crawled. This will be available in release 0.0.3.

Please send bug reports and suggestions to aleksander (at) or aleksander (at)


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