The latest two GRB detected by Hete‐2: GRB 051022 and GRB 051028

We present multiwavelength observations of the latest two GRB detected by Hete‐2 in 2005. For GRB 051022, no optical/nIR afterglow has been detected, in spite of the strong gamma‐ray emission and the reported X‐ray afterglow discovered by Swift. A mm afterglow was discovered at PdB confirming the association of this event with a luminous (MV = − 21.5) galaxy within the X‐ray error box. Spectroscopy of this galaxy shows strong a strong [O II] emission line at z = 0.807, besides weaker [O III] emission. The X‐ray spectrum showed evidence of considerable absorption by neutral gas with NH,X‐ray = 4.5 × 1022 cm2 (at rest frame). ISM absorption by dust in the host galaxy at z = 0.807 cannot certainly account for the non‐detection of the optical afterglow, unless the dust‐to‐gas ratio is quite different than that seen in our Galaxy. It is possible then that GRB 051022 was produced in an obscured, stellar forming region in its parent host galaxy.For GRB 051028, the data can be interpreted by collimated emission (...