------------------------------------------ ----------------------------- ----------------- --------------------- ------------------
  Observation                           Dates  t$_\mathrm{sci}$    Image rms                 beam size (PA)                Min and max baselines \[m\]   Flux calibrator   Bandpass calibrator   Phase calibrator
                                                   \[min\]        \[$\mu$Jy\]                                              (5th and 95th percentiles)                                           
  Band 6 - 12m             24, 27-30 Apr 2017       236.4             6.8       $0\farcs67\times0\farcs66$ ($-2.9\degr$)           41 and 312              J1229+0203          J1229+0203           J1215+1654
  Band 7 - 12m                    11 Dec 2016        48.8            30.0       $0\farcs46\times0\farcs37$ ($21.2\degr$)           48 and 410              J1229+0203          J1229+0203           J1215+1654
  Band 7 - ACA          20 Oct and 2 Nov 2016       135.1             245       $4\farcs3\times3\farcs4$ ($-76.4\degr$)             9 and 44                  Titan            J1256+0547           J1224+2122
                       22 Mar and 13 Apr 2017                                                                                                                                                   
  Band 7 - 12m+ACA                          -         -              31.1       $0\farcs47\times0\farcs38$ ($20.8\degr$)                -                       -                   -                   -
  ------------------ ------------------------ ------------------ ------------- ------------------------------------------ ----------------------------- ----------------- --------------------- ------------------

Despite the tentative evidence of planets producing these gaps around their orbits, neither the HD 107146 ALMA observations, nor the scattered light observations of HD 92945 and HD 131835, ruled out alternative scenarios in which planets are not orbiting within these gaps, but similar structure is created in the dust distribution through different mechanisms. These different scenarios have important implications for the inferred dynamical history of the system and planet formation. While a planet formed in situ could explain the data reasonably well, questions arise regarding how 