2026MNRAS.545f2034B

We report the detection of a glitch in the millisecond pulsar (MSP) PSR J0900-3144, which is included in the European, MeerKAT, and Parkes pulsar timing array (PTA) experiments. The data set combines observations from the MeerKAT, Nançay, Lovell, and Murriyang telescopes, spanning a total baseline of approximately 14 yr. The glitch occurred on MJD 59942(17), with a measured fractional spin frequency step of $\Delta \nu _{\rm g} / \nu = 1.15(13) \times 10^{-12}$. This event represents the third glitch detected in an MSP, following those in PSRs B1821-24A and J0613-0200. Although smaller in amplitude than the previous two, the glitch in PSR J0900-3144 is of a comparable order of magnitude. The updated MSP glitch rate is $2.5(1)\times 10^{-3}$ glitches per pulsar per year, which suggests it is likely that current PTAs will detect another MSP glitch within 5 yr. Using simulations, we demonstrate that such small glitches can go undetected, especially in short data sets such as those from new PTAs, and can bias the inferred achromatic noise model parameters, potentially leading to the down-weighting of the pulsar in gravitational wave background searches.