Silly questions
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by AlexandredOr
When we get this tag : Nice! There is no gravitational lens in this field! after studying an image, does it mean a contrario that in the other images, non tagged with this "Nice! There is no gravitational lens in this field!" there is inevitably one, or more, lens ??
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by ElisabethB moderator
No ! 😄
There is a subset of 600 (I think) images that have been carefully looked at by the scientist and they decided there was not a lens in them.
These images are also part of the training.Posted
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by AlexandredOr
Thank you Els 😄
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by FBloggs
Is it the whole sky that we are looking at or just particular sections?
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by AlexandredOr
Good question ! I'm impatient to know the answer... 8D
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by Capella05 moderator
Just a particular section of the sky 😃
You can find out more information here CFHTLS Survey
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by AlexandredOr
Thank you Capella05. Here is the answer : CFHTLS is a survey conducted with the CFHT 3.6m telescope using the Megacam camera. It targeted 4 patches of the sky, adding up to about 150 sq deg It's finally a very short piece of sky we are studying !
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by AlexandredOr
Another silly question : when arcs are not too close to the lens, must we mark them too ? 😕
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by Budgieye moderator
I think the software wants you to mark the arcs, not the centre galaxy.
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by ElisabethB moderator
I think Alexandre is asking about marking arcs that are far from the lensing galaxies.
For me, if an arc is too far away, it cannot be a lensed arc and I won't mark it.
Unless the lensing galaxy is very very massive, arcs will be close to the galaxy.Posted
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by AlexandredOr
Thank you both of you. 😉
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