It was considered that tenmondo and rekido in those days provided relatively highly accurate prediction of solar eclipse, but that since their personnel and equipment were only enough for keeping their standard time observation from eight to ten p.m. and from four to six a.m. and not enough for observing other phenomena, tenmon hakase and others were not guaranteed to observe unusual astronomical phenomenon without fail -- therefore, great many of unusual astronomical phenomena might have been left out of the tenmon misso.
もっとも、当時の天文道・暦道は日食の発生の予知の正確さについてはかなり高かったものの、その他の分野に関しては毎日戌の刻と寅の刻に行われる定時観測を維持するだけの人員と設備しかなかったと考えられており、天文博士らが確実に異常な天文現象を観測できる保証が無かったために、実際には異常な天文現象が発生しても、天文密奏が行われなかった例も相当数あったと考えられている。