I want the NGC number for leo of irregular galaxy
CREATE TABLE "2901_3000" (
  "ngc_number" real,
  "object_type" text,
  "constellation" text,
  "right_ascension_j2000" text,
  "declination_j2000" text
);
SELECT "ngc_number" FROM "2901_3000" WHERE "constellation"='leo' AND "object_type"='irregular galaxy';