Are those jets or artifact? using unwise layer


never mind, its a lense flare, very high luminosity stars are too darn bright

its actually diffraction spikes caused by the physical structure of the telescope observing the star. there are 4 beams that hold a secondary mirror (the one that focuses light) in place, in front of the primary mirror (the one that collects light from the stars and galaxies). if the secondary mirror had two beams holding it up, that went through the diameter of the opening, you would only see these spikes going one direction on either side of the star. i found this useful graphic showing how the shape of the beams affects the diffraction spikes

2 Likes


Figure 23a - Atlas Intensity Image in W1-4 for Betelgeuse from Tile 0884p075_ac51. For this very bright source, many causes of spurious or potentially spurious sources can be seen: ghosts and latents, diffraction spike objects, halo objects, etc

Or also see



Figure 4 - Examples of ghosts in the four WISE bands. The ghosts are indicated with a red circle and are seen in Bands 2 (upper right), 3 (lower left) and 4 (lower right). Ghosts are generally not visible in Band 1 single-frame images.
1 Like