Catching a Changing Look Quasar as it undergoes significant changes in accretion rate

We propose a joint TOO observation of Chandra (50 ks) and HST (2 orbits) of Mrk 1018. In February this year, we discovered the unambiguous case of a "changing look" quasar completing a full cycle: Mrk 1018 transformed from a Seyfert 1.9 to a Seyfert 1 in 1984, and it has just now transitioned back into a Seyfert 1.9. This state change is accompanied by extreme dimming in both X-ray and optical which might be still ongoing. Joint HST and Chandra observations are needed to constrain the current physical state of the accretion disk and embedded hot corona, respectively. This program will only be triggered if our optical monitoring programs detects a change of more than a factor of 5 in optical flux of Mrk 1018. Note that this proposal is accompanied by a GO proposal of the same object.