Any ideas?

https://www.legacysurvey.org//viewer/?ra=343.2093&dec=0.5513&layer=hsc-dr2&zoom=16

Very small, blue but fuzzy object.

Looks like a diffuse galaxy with some star formation occurring.

It’s tiny, unlike other diffuse blue galaxies, which suggests it’s very far away, in which case I would have expected it to be red-shifted. It’s certainly unusual insofar as I have not seen one quite like this before.

Its only around a billion light years away judging by the photo-z, so wouldnt expect too much effect from redshift. Most likely it’s a dwarf galaxy, which is why it looks so small.

Wouldnt surprise me if its a blue compact dwarf.

Like a Smurf, you mean? :rofl:

I don’t put a lot of faith in the photo-z indication. In this case the error is twice as big as the z value, so even the program doesn’t seem to believe its own calculation!

0.1 is a pretty standard uncertainty for photo-z from what I can tell. Even with the maximum z within error, it could only be around 2.4 billion ly away