This constellation, abbreviated as 'oph' has how many right ascension (in hm)?
CREATE TABLE "external_links" (
  "rank" real,
  "family" text,
  "abbre_viation" text,
  "constellation" text,
  "area_sq_deg" text,
  "area_msr" text,
  "per_cent_age" text,
  "right_ascension_hm" text,
  "decli_nation_dm" text,
  "quad" text
);
SELECT COUNT("right_ascension_hm") FROM "external_links" WHERE "abbre_viation"='Oph';