This directory contains test time-dependent internal field models constructed while preparing the CHAOS-1969 field model: - CHAOS-1969_POGO.mat: POGO-only model. Created using POGO data from 1965-1971. - CHAOS-1969_OBS.mat: Ground observatory-only model. Created using one month of POGO data and ground observatory data from 1960-1980. - CHAOS-1969_Wo_key_OBS.mat: Model without key ground observatories. Created using POGO data from 1965-1971 and ground observatory data from 1960-1980 with the data from key ground observatories removed. - CHAOS-1969_v2.mat: Main CHAOS-1969 model but with coestimated crustal field from degree 14-40. Created using POGO data from 1965-1971 and ground observatory data from 1960-1980. Full details of the CHAOS-1969 model are given in the article: Blangsbøll, Finlay and Kloss (2022) Localized origin at the core-mantle boundary of the 1969 geomagnetic impulse. Geophysical Research Letters, XXX. Further details of the test models are given in the associated Supplementary Information: Blangsbøll, Finlay and Kloss (2022) Supplementary Information to "Localized origin at the core-mantle boundary of the 1969 geomagnetic impulse". Geophysical Research Letters, XXX.