Euclid - Challenge the Machines

Frequently Asked Questions

Classification

What label should I give an image I am unsure about?
Only mark an image as a lens if you are sure there is a lens in the image, if not mark the image as not containing a lens.

Will the lens always be obvious?
Some images will contain obvious lenses, however some of the images will contain lenses that are difficult to identify. Some images will contain lenses that won't be possible to identify.

Shape

Will the lenses always be arc-shaped?
In general yes, however some of the lenses will be very close to the central lensing galaxy, and may not look arc shaped, but will still be a different colour.

Can an arc be around a non-central object?
No all the lenses in these simulations have been lensed by the galaxy in the centre of the image. Some may have large arcs or even rings, but these will still be around the central galaxy.

Colour

Will the arcs of lenses always appear blue?
The arcs in general should appear "bluer" than the central object, but may not always be an obvious blue. Arcs of lensed galaxies should appear as a different colour to the central object, but could still have similar colours.

General

What are the images I'm looking at?
The images are simulations designed in the style of the Kilo Degree Survey. The Kilo Degree Survey (KiDS) looks at the sky through 4 filters (u,g,r,i), which see the sky at different wavelengths. Both g and r filters see in the visible spectrum of light, the portion that our eyes also see in. The u filter sees in ultraviolet, and the i filter in the infrared. The colour images that you are looking at are produced by combining the g,r and i images to give a colour image.

Why are there brightly coloured rectangles on some images?
These appear on some images because of camera glitches or artefacts. They have been added to simulate camera glitches to makes the images an accurate representation as far as possible. If possible try to ignore these patches and classify regardless.