What is Date, when Constellation is "Delphinus"?
CREATE TABLE "targets" (
  "hd_designation" text,
  "constellation" text,
  "distance_ly" real,
  "spectral_type" text,
  "signal_power_k_w" real,
  "date_sent" text,
  "arrival_date" text
);
SELECT "date_sent" FROM "targets" WHERE "constellation"='delphinus';