# Tidal-feature tagging
Please identify all tidal features you see in this merger. Note that there can be more than one merger feature in the image. Hence, you should select multiple features if they are present.
Identifying these features can be tricky. They are often faint and can come across as either parts of the host galaxies or artefacts from bright sources or the image production process. Furthermore we urge to not worry about identifying these features "scientifically". Once you have gained a grasp of what each merger feature looks like, it will often be a case of trusting your eye and intuition and selecting the features that "seem" the most appropriate. We realise that this is not a very rigorous piece of instruction but the nature of the task is such. Every image that contains a merger will look different and will have different features associated with it. Hence, there are no patterns that can be followed while working on this task. So do not be afraid to choose the wrong feature. Your classifications, as long as performed intentionally and meticulously, will be of immense help to our scientific goals. As an example, below is an image of a merging galaxy.
In this image, we can spot a tail, a bridge and multiple nuclei. You may or may not agree with this classification and this is completely acceptable. A key part of this workflow is aggregating your classifications and using those aggregations to arrive at a final classification. Hence, even if you are apprehensive about your classifications, they will still be valuable to us.
Finally, there will often be mergers with multiple tidal features in them -- sometimes multiple of the same type and sometimes of different types!
These galaxies are particularly interesting and provide key insight to these sources. They may also be really hard to identify.
Assess the same central system in the three supplied views. Return all applicable feature names.
# Answer options
Tail
Stream
Shell or Fan
Double/Multiple Nuclei
Bridge
Remnant
Other - see field guide
System and task instructions
System instruction
Task instruction
Please select all tidal features you see in this merger. You can, and should, select multiple features if they are present.
Select every applicable feature. Return an empty list if none apply; do not repeat labels.
