Only if you really have to.

Iron the shirt inside out or with baking-paper in between and never use steam directly on the artwork.

Fun fact: Heat is energy, too. Some glow pigments may briefly light up while they’re being heated. That’s because warmth can release energy that was already stored inside the pigment. It looks pretty cool – but it’s not a replacement for sunlight or UV light, and excessive heat can permanently damage both the artwork and the fabric.

I’d simply avoid ironing the painted areas whenever possible.