how many times was the exposures 53?
CREATE TABLE "observations_made_of_the_hdf_s_with_the_" (
  "camera" text,
  "filter" text,
  "wavelength" text,
  "total_exposure_time" text,
  "exposures" real
);
SELECT COUNT("camera") FROM "observations_made_of_the_hdf_s_with_the_" WHERE "exposures"=53;