What is the average NGC number of everything with a Right ascension (J2000) of 05h33m30s?
CREATE TABLE "2001_2100" (
  "ngc_number" real,
  "object_type" text,
  "constellation" text,
  "right_ascension_j2000" text,
  "declination_j2000" text
);
SELECT AVG("ngc_number") FROM "2001_2100" WHERE "right_ascension_j2000"='05h33m30s';