CREATE TABLE table_name_77 (declination___j2000__ VARCHAR(255), constellation VARCHAR(255), right_ascension___j2000__ VARCHAR(255))
what is the declination (j2000) that has a constellation of hydra and a right ascension (j2000) of 10h46m44.9s?
    
SQL: SELECT declination___j2000__ FROM table_name_77 WHERE constellation = "hydra" AND right_ascension___j2000__ = "10h46m44.9s"