NICER observation list: Target ID 355301

We propose the sixth NICER observation of RX J0806.4-4123 to complete the timing campaign started in Cycle 1. The goal is to obtain an accurate timing solution for this isolated neutron star. Previous constraints by XMM-Newton yielded a frequency derivative with a large uncertainty that is consistent with both spin-up or spin-down of the neutron star. A better constrained timing solution is needed because recent near-infrared observations discovered an extended source at the position of the neutron star which could indicate a circumpulsar disk. The proposed observations will allow us to test whether RX J0806.4-4123 has timing properties different from those of its siblings, the other six of the so-called Magnificent Seven.