The phrase "ascertained when the" is correct and usable in written English.
It can be used when discussing the determination of a specific time or condition related to an event or situation.
Example: "The results of the experiment were ascertained when the final measurements were taken."
Alternatives: "determined when the" or "established when the".
Last night Dirk Vande Beek, Mr. Cheney's spokesman, said he was trying to ascertain when the Cheneys' full tax returns may be disclosed.
The Tribune board is expected to choose one bidder with whom it will enter exclusive negotiations, but it was impossible on Tuesday to ascertain when the board will meet or whether it will force the three bidders into a Strat-O-Matic playoff to determine the finalist.
The approach ascertains when the system needs to undergo maintenance, repair and overhaul before failure occurs.
A critical aspect is to ascertain when the measured (including uncertainties) is substantially lower than the reference/limiting value.
Plus, it is virtually impossible to ascertain when the studio disburses payouts to its "partners," including director Jerry Bruckheimer.
Accessed from a web browser, this information enables farmers to work out when best to spray large areas of farmland, because they can ascertain when the land is dry enough, when the wind speed is low enough to permit spraying, and when there is a long enough time window before the next rainfall to ensure that the spraying is effective.
In this way, it was possible to ascertain when the woman would become eligible for NPNL and F52 measurements.
The third new study is still ongoing and the authors have been contacted to ascertain when the published data will be available (Cox 2014).
According to Article 580, referenced in the charges, a crime is only ascertained when intent to commit the crime has been established.
Specificity of ChIP was ascertained when no amplification was obtained in the group where the antibody against histone H3 was omitted.
