eGZeLENS — The extensive Galaxy Zoo LENsing Survey

We’ve go exciting news; Galaxy Zoo has gotten time on our largest telescope
yet, the enormous 8m Gemini South telescope…

Hi there

Some of you may have had some interaction with me on the GalaxyZoo Forum on the topic of Gravitational Lenses. My name is Aprajita Verma and I am a researcher at the University of Oxford. I primarily work on galaxies at high redshift trying to understand their nature as we see them, how they began their lives and postulating about their fate.

When Kevin Schawinski first highlighted the Gravitational Lens forum to me, I have to say I was astounded and impressed by the sheer volume of activity and interest in identifying potential gravitational lenses by the Galaxy Zoo community. I have been interested in gravitational lenses since studying lensed objects such as the Cloverleaf Quasar and IRAS F10214+4724 as part of my PhD thesis. Subsequently, I have become involved with a number of observational projects that use integral field spectrographs (IFS) and I thought it would be great to get some IFS data on some of the systems that you guys have been identifying as potential lenses. An IFS is an imaging spectrograph, i.e. it takes an image of an object but the light that reaches each pixel of that image is simultaneously dispersed so that we can measure the spectrum of the object in each pixel that it covers. Observing gravitational lenses with integral field spectrographs provides us with three key advantages.

(1) It bypasses the normal 2 stage process of imaging followed by spectroscopy of the components.

(2) All of the multiple images (if present) or the full extent of any arcs can be observed in a single shot, giving us a multiplex advantage in sensitivity and also in efficiency (since we observe the full extent of the lensed images) than can be achieved with traditional long-slit spectroscopy.

(3) We can also measure the kinematics of the lensing galaxy which is important for determining an accurate lens model.


The Gemini North Telescope, from Gemini.

As an initial attempt, we applied for observing time for IFS observations with the 8m Gemini Telescope in Chile (see This is one of the world’s largest telescope with a twin telescope (hence the name Gemini) in the northern hemisphere on Mauna Kea, Hawaii. These telescopes are located at exceptional sites with very advanced instrumentation. GMOS or the Gemini Multi-Object Spectrograph has an integral field unit that is sensitive to light from ~450nm-900nm. The UK Gemini time allocation group has awarded us 12hrs of observing time to observe our highest priority targets. After trawling through your 120+ pages of entries and having the insightful opinion of lensing expert Phil Marshall (Univeristy of California, Santa Barbara) we have identified 5 high priority targets for confirmation as lenses with GMOS. Unfortunately we were only awarded low priority time (which means higher priority programs will be observed first), nevertheless we are hopeful that we can obtain data on at least one or two of the lens candidates. If you are interested, please keep an eye on the Gravitational Lens forum discussion where I’ll be discussing the shortlist and reporting on progress. The first stage is the definition of the science observations which are due on Monday 14th July that I am currently working on. The 2008B semester starts on the 1st August, so it’s 6 months of keeping fingers crossed for some data!


GMOS on the telescope, from the Durham AIG.

Sorry to not have posted info on this proposal before submission, but needless to say all Galaxy Zoo members are co-investigators and your thoughts and inputs are always welcome. None of this would have been possible without your hard work and enthusiasm. Thank you!

In an attempt to identify the Galaxy Zoo Gravitational Lens group and projects, Matthias Tecza (an IFU expert at Oxford who is involved with the proposal) and I came up with a project acronym of eGZeLENS (like “excellence”) – The extensive Galaxy Zoo LENsing Survey. I hope you all approve.

If you are interested, please keep an eye on the Gravitational Lens forum discussion where I’ll be discussing the our shortlist and reporting on progress.

About The Zooniverse

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12 responses to “eGZeLENS — The extensive Galaxy Zoo LENsing Survey”

  1. elizabeth siegel says :

    awesome news!!! thanks for letting known.

  2. Pat says :

    Thanks Aprajita!!! Fingers are crossed here. Brillant news.

  3. Alice says :

    Wow, how cool can you get! Give the lenses my greetings! What a great birthday present for Gumbosea too. What is it with Galaxy Zoo and telescopes? All of a sudden they all seem to be coming our way!

    Thanks for all the trawling – any way you could tell us the SDSS reference numbers of your five high priority lenses? And were they all newly discovered by us?

  4. Joseph K. H. Cheng says :

    It would appear that the birthday presents for the ZOO will keep coming. Fabulous news & thanks for the detailed explanation.

  5. fluffyporcupine says :

    eGZeLENT news! πŸ˜€ cant wait to see the top 5. Thanks for keeping us informed, keep up the great work!

  6. Hanny says :

    eGZeLENT indeed! πŸ˜€

  7. Joseph K. H. Cheng says :

    I forgot to mention that the project acronym of eGZeLENS is both imaginative and a morale booster. Thank you very much for your creativity, Aprajita.

  8. Adam Primus says :

    Great cookie-jar of Zanzibar! At this rate all telescopes will be working on GZ identified objects soon!
    As Monty Burns might say, “Egzelen-t!”

    p.s. I thought that we (the UK) had withdrawn funding & participation in Gemini… Que?

  9. Alice says :

    Perhaps that issue has two faces . . .

    (Sorry about that.)

    Was it because Kevin and Aprajita and some of the other zookeepers are in the States?

  10. Aprajita says :

    Hi everyone,

    Thanks for your comments. There has been quite some discussion on the UK’s involvement with Gemini. Actually the UK are still involved with Gemini but are looking for partners to share their contribution.

    We’ll be revealing the priority list as we get data, which depends upon a number of things, but I’ll be posting updates on the Grav. Lens forum. All the targets I put in my list of favourites have not been published by anyone else, so they are new lens candidates. But we won’t know if they are true lenses until we get some data.

    Let’s keep our finger’s crossed!


  11. pluk says :

    Very cool news πŸ™‚

  12. anetak says :

    Ve-e-e-ry interesting my dear Watson.

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