Observed minus calculated (O-C) diagram of TOI-1130 b (top) and TOI-1130 c (bottom). The calculated T₀s were determined from the linear ephemeris: T_lin,b,N = 2392.81470 ± 0.00021 (0.01260) + N × 4.078668 ± 0.000002 (0.000097) BTJD_TDB, and T_lin,c,N = 2392.66995 ± 0.00007 (0.00218) + N × 8.349560 ± 0.000002 (0.000023) BTJD_TDB, with formal (thin-black area) and bootstrap (between round brackets, grey area) uncertainty. Ground-based T₀s presented in Sect. 2.1.3 and analysed in Sec. 4.1 are reported as ground. T_ref is the reference time of the linear ephemeris plotted as dashed-grey vertical line. All the times are in BTJD, that is BJD_TDB − 2 457 000.