Bars side project

Dear Zooniverse users,

We’d like to re-draw [no pun intended!] your attention to the GalaxyZoo Google-powered Bar drawing website: simply log in with your Zooninverse username and password. Please note, this site works best using FireFox.

GZ2 Galaxy as seen in Google Maps

GZ2 Galaxy as seen in Google Maps

In this project, we ask for more specific observations and even drawing to be performed on a selection of galaxies. The sample size is relatively small, and 8000 [of the 8400] galaxies have been classified 5 times. The remaining 400 have been examined 6+ times.

We are starting to collate votes, for example we see some excellent agreement between users, e.g. See the picture below, which shows the bars as drawn on the above galaxy by different users, but we still need a few more classifications for each galaxy, to really be able to produce science.

One such science question we’d like to answer is, “How does the presence of a bar, affect the galaxies properties?”. GZoo allows us to study this question with 20- times more data than previously possible.

GZ2 Galaxy with Bars drawn by users.

GZ2 Galaxy with Bars drawn by users.

We’d also like to thank the GZ users for the hard work they have put into the site since it’s launch in October.


Ben Hoyle, on behalf of the GZ-bar drawing team

About The Zooniverse

Online citizen science projects. The Zooniverse is doing real science online,.

4 responses to “Bars side project”

  1. Alice says :

    Back in the bars, and have tweeted this 🙂

    More work for the programmers: do you think you could have a title? I was only able to access this article by clicking on the picture, which seemed a bit silly. Also it would be very nice if I didn’t have to type out all my details every time, in this almost-white font on a white background. Any chance our details could be remembered again?

    Thanks! Love the bars. Also curious, if that picture is supposed to show exactly what people draw I must be doing it all wrong – that seems to be ellipses around the galaxy and straight lines for the bars, while I thought were were supposed to draw thin ellipses around the bars?!?

  2. Ben says :

    Hi Alice!
    You’re quiet right. I have shown only the lines which people drew marking the length of the bar, and not the full bar ellipses. The image gets a bit messy if I do that!

    The ellipses here show somthing else; The thick green line is the original isophotal ellipse as determined by the SDSS photometric pipeline. The thin purple ellipse is the isophoalt ellipse as modified by a user to ‘better’ fit the light profile. The thick purple ellipse is another SDSS fit parameter, within which 90% of the r band galaxy flux is contained.

    I think that people have fit the length of the bar well to this galaxy.

    I hope this answers your questions.

    Thanks for bringing this up & regards,


  3. Alice says :

    Ooooh, this time my details are remembered – thanks programmers 😀

    And very many thanks Ben! It makes a LOT more sense now! I agree that the ellipses are fit pretty well. Your blog post worked well, too, I spent ages on the bars last night, very enjoyable indeed.

  4. elizatbeth says :

    Wonderful project ! Great fun! learn something new everyday.

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