  We use high-resolution imaging spectroscopy with the Swedish 1-m Solar
Telescope (SST) to study the transient brightenings of the wings of the Balmer
Halpha line in emerging active regions that are called Ellerman bombs.
Simultaneous sampling of Ca II 854.2 nm with the SST confirms that most
Ellerman bombs occur also in the wings of this line, but with markedly
different morphology. Simultaneous images from the Solar Dynamics Observatory
(SDO) show that Ellerman bombs are also detectable in the photospheric 170 nm
continuum, again with differing morphology. They are also observable in 160 nm
SDO images, but with much contamination from C IV emission in transition-region
features. Simultaneous SST spectropolarimetry in Fe I 630.1 nm shows that
Ellerman bombs occur at sites of strong-field magnetic flux cancelation between
small bipolar strong-field patches that rapidly move together over the solar
surface. Simultaneous SDO images in He II 30.4 nm, Fe IX 17.1 nm, and Fe XIV
21.1 nm show no clear effect of the Ellerman bombs on the overlying transition
region and corona. These results strengthen our earlier suggestion, based on
Halpha morphology alone, that the Ellerman bomb phenomenon is a purely
photospheric reconnection phenomenon.
