Archive by Author | chrislintott

See you in Hull

As part of the celebrations of Galaxy Zoo’s tenth birthday (!), we’ll be hosting sessions at the UK’s National Astronomy Meeting in Hull.

I’ll be giving a public talk on Monday 3rd July – ticket details coming shortly. Then on the 4th and 5th July there will be scientific sessions on the theme of Modern Morphologies: 10 years of Galaxy Zoo.

The session abstract is as follows:

As our community has developed increasingly sophisticated techniques to analyse the data in large galaxy surveys, we have seen a resurgence of interest in galaxy morphology. Clues to a galaxy’s formation and evolution are recorded in its morphology, and we are now seeing growing evidence that its evolution may also be affected by its internal structures. This session, marking the 10th anniversary of Galaxy Zoo, will discuss results from the use of morphological markers including the effects of bars, bulges and disks.

and researchers are welcome to submit via the abstract form. Though this is part of the formal scientific conference, we’ll make sure our worldwide community are included in what’s going on.

Watch this space for more Galaxy Zoo birthday news shortly.

Kyle’s Legacy

Screen Shot 2016-05-31 at 10.55.36

Good news! Early this morning UK time, we submitted the paper describing the finished data release for the third iteration of Galaxy Zoo to the journal Monthly Notices of the Royal Astronomical Society. It’s taken an enormous amount of work to get to this point, in particular in understanding how to account for the effects of distance on classifications. Most of that work was done by Kyle Willett and Mel Galloway from the University of Minnesota (Kyle gave a sneak preview here), and it was finished just in time because Kyle leaves us tomorrow.

Kyle and friend at his leaving party.

Kyle and friend at his leaving party.

Kyle has had an enormous impact on Galaxy Zoo since he came on board in 2011. As well as publishing papers on star formation and the enormous data release paper for Galaxy Zoo 2, he’s been the person making images, coordinating what’s seen on the site and keeping an eye on classifications as they’ve come in. Just as importantly, he’s been a prolific contributor to this blog, playing a leading role in keeping our important collaborators, the volunteers, in touch with what’s going on. It’s not just Galaxy Zoo, either, as Kyle has also played a critical role in the Radio Galaxy Zoo team, and has made major contributions to their recent papers too. He will be much missed by all of us, though we wish him well with his future endeavours.

Models of Merging

Once upon a time, there was an experimental project called Galaxy Zoo: Mergers. It used ancient, mystical technology to allow volunteers to run simulations of merging galaxies on their computers, and to compare the results of many such simulations. Their mission: to find matches to more than fifty nearby mergers selected from Galaxy Zoo data.

The wonderful Penguin Galaxy, studied in the project.

The wonderful Penguin Galaxy, studied in the project.

Amongst the chosen galaxies were not just run-of-the-mill, everyday mergers, but also the various oddities that the volunteers found, such as the Penguin galaxy. The team led volunteers through a series of tournaments designed to pit potential solutions for a particular galaxy against each other. In total, more than 3 million simulations were reviewed producing the results described in the paper, now accepted by the journal MNRAS, and in the dataset visible at the main Galaxy Zoo data repository. This represents a huge amount of effort, and a speeding up of the process – in the paper, we note that previous fits to mergers have taken months of effort to complete.

Which is not to say the analysis, led by Anthony Holincheck and John Wallin, has been easy. In a recent email to the Galaxy Zoo team, John commented:

This is by far the most complex project I have ever worked on. Most papers that model interacting galaxies contain one or two systems where the author uses a few dozen simulations. We just published a paper that modeled 62 different systems using a brand new modeling technique where the 3 million simulation results were reviewed by citizen scientists. Best of all, the 62 models were done using the same code and the same coordinate system so others can reproduce them. Doing this with other published simulations is nearly impossible.

I know an immense amount of effort went into making sure that the results weren’t wasted, and the paper thus represents a happy ending to a tale that’s been running a long time. But it is not really an end; we are already planning to observe some of these galaxies as part of surveys like MaNGA that can measure the way that the galaxies’ components are moving today, allowing us to test these models. We also hope a library of models might be useful for other astronomers, and will be looking to try and revive this kind of project.

Read more about Galaxy Zoo: Mergers in this old blog post

Eight Years of Galaxy Zoo

It’s our eighth birthday! The team have done a great job exploring the various ways the number eight connects to the Galaxy Zoo Universe and that collection of blogs does a brilliant job of illustrating the dramatic variety of places we’ve explored together. Some of them were familiar, but others we didn’t even dream of before the start of the project.

An 8 for our 8th birthday!

An 8 for our 8th birthday!

Once you start thinking about it, thinking of Galaxy Zoo as an exploration, as a journey undertaken as a group makes a lot of sense. Lots of you have joined us for the whole journey, as we’ve travelled further and further from familiar ground, while others – just as welcome – have walked only a little way. The science team, too, has grown as it has become apparent quite how much can be done with your classifications, and the whole grand parade has attracted a following of computer scientists, web developers and other assorted camp followers.

I’m writing this on my way to report on the arrival of New Horizons at Pluto for the Sky at Night. For the first time, we’ll see close up images of a world that until now has been little more than a point of light. The missions is part of the glorious tradition of Solar System exploration, but our journey through the datasets provided by the Sloan Digital Sky Survey and by Hubble are voyages of exploration too. We need not travel to distant galaxies to understand them; encountering something new and never-before-seen in your web browser is thrill enough. Thanks for all the classifications of the last eight years – here’s to many more.


Sunset in Hawai’i


Hello from the summit of Mauna Kea, Hawai’i! We’re here to follow up on a host of Galaxy Zoo blue ellipticals, trying to use the Caltech Submillimeter Observatory to catch the signature of Carbon Monoxide – gas which might provides the fuel for star formation.

Sadly, we’re not in Hawai’i – I’m in the office in Oxford (my sunrise is below), Becky is in Bristol and we’re joined by Meg Schwamb from Planet Hunters on her first extragalactic observing run. Conditions look good, if a bit windy, and I’ll try and keep you informed as the night wears on.

2014-07-12 06.29.48


EDIT: We have an open dome and the weather is looking good. Here’s a dark webcam image you can squint at to pick out a telescope and sky.

Screenshot 2014-07-12 07.30.29

And first observations for calibrations are on Mars! Here’s an excitingly noisy spectrum with a nice broad absorption line in the middle – you’re looking at CO (carbon monoxide) in the atmosphere of Mars. The width can even tell you about the current wind speed on Mars. From Oxford to Hawaii to Mars to back to you at home.

Screenshot 2014-07-12 07.34.29



EDIT : Well, that was interesting. It turns out it helps if you know a telescope – none of us have used the CSO before and it’s been quite hard work to get our heads round the right software. Still, we successfully observed our first target – an unprepossessing, rather distant blue elliptical by Sloan standards (see below) and on first glance didn’t quite see anything. It set before we could quite confirm that there was nothing there to see, and we’ve moved on to a second galaxy, stopping off on the way by a cool star in order to calibrate the system.


EDIT : End of a long night. One disadvantage of observing remotely is that we have to be very cautious, so we’re commanded to shut the telescope an hour before sunrise. We got data, certainly, but it’s not one of those nights in which wonderous things are apparent immediately. We have more chances for the rest of the week if the weather cooperates, so watch this space.

Thanks to the Forum – and Farewell


After very nearly seven years online, and over 650,000 posts by its members, the time has come to shut the doors on the original Galaxy Zoo Forum. Originally an afterthought, created to deal with the fact that we couldn’t possibly deal with the volume of mail that we were getting, the Forum quickly established itself as a very special place. It generated science – the Voorwerp and its diminutive colleagues, the Voorwerpjes, the Peas and much more came from discussions amongst its boards, as well as such random fun things as the letters that power My Galaxies.

It was also a very civilized place – entirely due to the standards set by Alice and the team of moderators that followed, especially Graham and Hanny who have served most recently. The forum inspired much of what the Zooniverse tries to do today, but time has moved on and we have taken, in collaboration with the moderation team, the decision to shut the forum down. The vast majority of Galaxy Zoo volunteers now interact with each other via Talk, not the forum, and that’s where we want to concentrate our efforts. Closing the forum will allow us to abandon the archaic software that runs the forum itself, and free the moderators from the increasingly onerous task of clearing the forum of spam. It will be preserved intact as a valuable resource, and a record of discussion during the first seven years of Galaxy Zoo’s life.

Feedback and discussion about everything in the Zooniverse is still welcome, of course. As well as Talk, there are blog comments, and thanks to a recent grant from the Alfred P. Sloan Foundation, we’re going to be rebuilding Talk over the next few months. If you’d like to help shape the future of discussion and community in the Zooniverse, then there’s a form for feedback available here. I’m looking forward to reading what you have to say.


Galaxy Zoo 2 data release

It’s always exciting to see a new Galaxy Zoo paper out, but today’s release of our latest is really exciting. Galaxy Zoo 2: detailed morphological classifications for 304,122 galaxies from the Sloan Digital Sky Survey, now accepted for publication in the Monthly Notices of the Royal Astronomical Society, is the result of a lot of hard work by Kyle Willett and friends.

Get back to work, Kyle!

Lead author Kyle, seen here taking a rare moment away from reducing Galaxy Zoo data.

Galaxy Zoo 2 was the first of our projects to go beyond simply splitting galaxies into ellipticals and spirals, and so these results provide data on bars, on the number of spiral arms and on much more besides. The more complicated project made things more complicated for us in turning raw clicks on the website into scientific calculations – we had to take into account the way the different classifications depended on each other, and still had to worry about the inevitable effect that more distant, fainter or smaller galaxies will be less likely to show features.

We’ve got plenty of science out of the Zoo 2 data set while we were resolving these problems, but the good news is that all of that work is now done, and in addition to the paper we’re making the data available for anyone to use. You can find it alongside data from Zoo 1 at One of the most rewarding things about the project so far has been watching other astronomers make use of the original data set – and now they have much more information about each galaxy to go on.

(Most) Galaxy Zoo Papers now Open Access

As announced on the Zooniverse blog, Oxford University Press have agreed that to make the Zooniverse papers published in Monthly Notices of the Royal Astronomical Society open access. While they’ve always been freely available on astro-ph, it’s nice that everyone who contributed can now get access – for free – via the main journal site.

Machine Learning & Supernovae

This post, from Berkley statistician Joey Richards, is one of three marking the end of this phase of the Galaxy Zoo : Supernova project. You can hear from project lead Mark Sullivan here, and from the Zooniverse’s Chris Lintott here.

Thanks to the efforts of the Galaxy Zoo Supernovae community, researchers in the Palomar Transient Factory collaboration have constructed a machine-learned (ML) classifier that can reliably predict, in near real-time, whether each candidate is a real supernova. ML classification operates by employing previously vetted data to teach computer algorithms a statistical model that can accurately and automatically predict the class for each new candidate (i.e., real transient or not) from observed data on that object. The manual vetting of tens of thousands of supernova candidates by the Galaxy Zoo community has provided PTF an invaluable data set which could be used to accurately train such a ML classifier.

The ML approach is appealing for supernova vetting because it allows us to make probabilistic classification statements, in real-time, about the validity of each new candidate. Further, it allows the simultaneous use of many data sources, including both new and reference PTF imaging data, historical PTF light curves, and information from external, on-line sources such as the Sloan Digital Sky Survey and the U.S. Naval Observatory. In total, our automated ML algorithms use 58 metrics about each supernova candidate, all of which are available within seconds after PTF detection of the candidate. These metrics—features in ML parlance—are fed into a sophisticated algorithm, which uses the aggregate of information from more than 25,000 historical supernova candidates which were rated by the Zoo to instantaneously determine whether each newly observed candidate is a supernova.

Human vs Machine scores for Supernova candidates

False Positive rate and missed detection rate for human and machine classifiers.

Our “ML Zoo” has been operating since the beginning of 2012 and has been thoroughly tested against the Human Zoo scores. We found that the ML Zoo scores correlate reasonably well with the average Human Zoo scores for 7000 supernova candidates observed during the first 3 months of 2012 (Figure 1). We also discovered that the ML Zoo is more effective at finding supernovae. In Figure 2 we show a plot of the supernova false positive rate (% of non-supernovae that were classified as supernovae) versus the supernova missed detection rate (% of confirmed supernovae that were classified as a non-supernovae) by both the Human an ML Zoos for 345 spectroscopically confirmed supernovae from 2010. Indeed, the ML Zoo achieves a smaller missed detection rate at each false positive rate.

Joseph Richards works in the Statistics and Astronomy departments at
the University of California, Berkeley as an NSF-sponsored
postdoctoral researcher supported by an interdisciplinary
Cyber-enabled Discovery and Innovation grant. His main area of focus
is astrostatistics and he holds a Ph.D. in Statistics from Carnegie
Mellon University. In his academic research, he has developed
sophisticated statistical and machine learning methodologies to
analyze large collections of astronomical data.

Supernova Project Retires

This post, from project lead Mark Sullivan of Oxford, is one of three marking the end of this phase of the Galaxy Zoo : Supernova project. You can hear from Joey Richards of PTF here, and from the Zooniverse team here.

Since August 2009, Galaxy Zoo Supernovae has been helping astronomers in the Palomar Transient Factory (PTF) find exploding stars, or supernovae, in imaging data taken with a telescope in Southern California. This project has been tremendously successful – Galaxy Zoo Supernovae has uncovered hundreds of supernovae in the PTF data that would otherwise have been missed. These discoveries have directly resulted in scientific publications, with many more in the pipeline, and have been observed on telescopes all over the world, including the 4.2-metre William Herschel Telescope. For example, my colleague Dr. Kate Maguire’s paper includes 8 supernovae found by the Zoo, which were subsequently observed using the Hubble Space Telescope. This allowed her to examine the ultraviolet properties of several thermonuclear ‘type Ia’ supernovae, the same type as those used in the original discovery of dark energy and the accelerating universe. The ultraviolet is a probe of the composition of the exploding star, and allowed her to test whether type Ia supernova properties change with time as the universe ages and becomes enriched with heavy elements.

But – all good things must come to an end. One of the goals of Galaxy Zoo Supernovae was to use the Zoo classifications to improve the algorithms that surveys such as PTF use to find supernovae automatically. And the good news is that, after two years of hard work, we have managed to do just that. The full details are explained in a separate blog posting by Dr. Joey Richards at the University of California at Berkeley.

I’d like to take this opportunity, on behalf of everyone involved with PTF, to thank you all for your time and effort in classifying these supernovae for us. We realise how much effort you’ve put in, and it has been very much appreciated.

For those of you who have become addicted to supernovae, don’t panic – there may be further supernova-related projects in a few months time. In the mean-time, watch this space for more publications based on Galaxy Zoo Supernovae discoveries!