In this paper, we propose a cooperative guidance law aimed to achieve coordinated impact angles with limited observation on target information. The primary challenge lies in establishing an appropriate communication graph among all missiles and devising an algorithm to estimate target acceleration information during engagements. To address this, we propose a specific communication topology and employ a numerical integration-based estimation method. Additionally, a distributed algorithm is introduced to facilitate consensus on target acceleration estimation. Building upon these foundations, we design an optimal-control-based distributed guidance law for each missile. Performance of the proposed guidance law is validated through numerical simulations.