The requirement for the Sun angle was particularly restrictive, limiting the launch date to one day per month.
ðə ɹᵻkwˈaɪɚmənt fɚðə sˈʌn ˈæŋɡəl wʌz pɚtˈɪkjʊlɚli ɹᵻstɹˈɪktɪv, lˈɪmɪɾɪŋ ðə lˈɑːntʃ dˈeɪt tə wˈʌn dˈeɪ pɜː mˈʌnθ.