Well, the Hijri date 11 Rajab 1280 corresponds to the Gregorian date Monday, 21 December 1863. This date lies in the seventh month of the Hijri year 1280 AH, which is Rajab of 1280 AH. Both this Hijri and Gregorian date occur on the single day that is Monday without any doubt. The Arabic date 1280/07/11 is calculated using the Umm Al-Qura calendar and the sighting of the moon. One thing to remember is that this Arabic date may occur on different Gregorian date depending upon the region and country and obviously the moon.
If you are still not sure about the date then you can use our Arabic date converter.
The following is the conversion of the Gregorian date 21 December 1863 to its equivalent Arabic date.
The following is the conversion of the Arabic date 11 Rajab 1280 AH to its equivalent Gregorian date.
فَنَادَتْهُ ٱلْمَلَٰٓئِكَةُ وَهُوَ قَآئِمٌۭ يُصَلِّى فِى ٱلْمِحْرَابِ أَنَّ ٱللَّهَ يُبَشِّرُكَ بِيَحْيَىٰ مُصَدِّقًۢا بِكَلِمَةٍۢ مِّنَ ٱللَّهِ وَسَيِّدًۭا وَحَصُورًۭا وَنَبِيًّۭا مِّنَ ٱلصَّٰلِحِينَ
And the angels called to him as he stood praying in the sanctuary: Allah giveth thee glad tidings of (a son whose name is) John, (who cometh) to confirm a word from Allah lordly, chaste, a prophet of the righteous.
Surah Aal-i-Imraan(3:39)