Read the action column
A photograph of a signing ceremony can establish that a signature took place. It does not necessarily show that the state has completed every step needed to become bound by the treaty. The significance of the act depends on the treaty and the kind of signature involved.
The UN Dag Hammarskjöld Library's treaty explanation distinguishes signature subject to ratification from ratification itself. The former does not establish consent to be bound, although it carries an obligation concerning the treaty's object and purpose. Ratification is the international act expressing that consent where the parties use that procedure.
Sources: s1
There are other routes and another clock
The UN Treaty Handbook also explains definitive signature and accession. A definitive signature can express consent without a later ratification; accession can have the same legal effect as ratification. Entry into force is a separate issue governed by the relevant provisions and conditions. Avoid treating these different dates as interchangeable milestones.
For a factual status note, record the exact treaty, depositary, state, type of action and date. Read the status table's notes and the treaty's entry-into-force clause. If the question concerns a past date, preserve the historical cutoff. A current table may contain actions that had not occurred at the time under discussion.
Report status before interpreting consequences
A careful research answer can say that a named instrument was deposited on a specified date and identify the supporting record. Whether a particular obligation applies in a concrete dispute may require additional legal analysis, reservations and domestic law. The document-research method here helps establish the record; it does not replace that analysis.