Context : Asteroid ( 130 ) Elektra belongs to one of the six known triple asteroids in the main belt , so its mass has been reliably determined .

Aims : We aim to use all available disk-resolved images of ( 130 ) Elektra obtained by the SPHERE instrument at VLT and by the Nirc2 of the Keck telescope together with the disk-integrated photometry to determine its shape model and its size .
The volume can be then used in combination with the known mass to derive the bulk density of the primary .

Methods : We apply the All-Data Asteroid Modeling ( ADAM ) algorithm to the optical disk-integrated data , 2 disk-resolved images obtained by the SPHERE instrument and 13 disk-resolved images from the Nirc2 of the Keck telescope , and derive the shape model and size of Elektra .

Results : We present the shape model , volume-equivalent diameter ( 199 \pm 7 km ) and bulk density ( 1.60 \pm 0.13 g cm ^ { -3 } ) of the C-type asteroid Elektra .

Conclusions :