recorded as having studied with Sayyid Abdullah bin Aqil bin Yahya (Sayyid Usman's father)
in Betawi, where this teacher has given him a diploma (scientific license).
Like other Nusantara scholars, Shaykh Muhammad Mukhtar also studied at the Hijaz.
Some of his teachers in the Hijaz include Ahmad Nahrawy, As-Sayyid Abdul Bary Ridwan al-
Madany (d. 1358 H/1938 AD), Muhammad bin Abdul Kabir al-Kattany, and As-Sayyid
Muhammad bin Ja'far al-Kattany (Abdul Jabbar et al., 2019; Umar Abdul Jabbar, 1982).
Meanwhile, his students included Shaykh Sulaiman Samdani (d. 1349 H/1930 AD) and Shaykh
Muhammad Zein Batubara (d. 1388 H/1968 AD). His works are "Ittihāf as-Sādāt al-
Muhadditsīn bi Musalsalah al-Arba'īn". While his work in the field of astronomy is "Taqrīb
al-Maqshad fī al-'Amal bi ar-Rub' al-Mujayyab"(Abdul Jabbar et al., 2019; Umar Abdul
Jabbar, 1982).
In this “Taqrīb al-Maqshad fī al-'Amal bi ar-Rub' al-Mujayyab”, which is the 10th
chapter, the discussion on timing and calculation of zawal (Fi Ma'rifah al-Auqāt al-Madzkūrah
'alā Hisāb as- Sā'ah az-Zawāliyyah), Muhammad Mukhtar stipulates that the standard of dawn
is 19 degrees (Hidayatullah, 2019).
"And as for the dawn, then add the radius distance above the angle of 19 with the original
mury on the appropriate, then subtract on the contrary. And anything between the line and the
end in those two states is the dawn of 12 hours” (Hidayatullah, 2019).
As for the time of Isha, he set a standard of 16 degrees for the first Isha and 19 degrees
for the second Isha. He said as follows,
"And as for the first and second Isha, then add bu'd quthr above angle 16 with the original
mury on al-muwāfaqah, then subtract it from al-mukhālafah. While between the line and the
beginning in the two conditions is the first Isha over 6 hours, do it like that with an angle of 19
then the result is the second Isha” (Hidayatullah, 2019).
Muhammad Ma’shum bin Ali (d. 1351 H/1933 AD)
His full name is Muhammad Ma'shum bin Ali bin Abdul Muhyi Maskumambang. He
was born and raised in a boarding school environment, namely in Maskumambang, Gresik,
around the year 1305 H/1887 AD. Meanwhile, he died on the 24th of Ramadan 1351 H/08
January 1933 AD. Shaykh Ma'shum bin Ali has many skills, including the field of reckoning.
(arithmetic), astronomy (astronomy), sharaf and nahwu. His ability in various sciences made
K.H. Hasyim Asy'ari was amazed until he finally married his daughter (Khairiyah). From this
marriage, he was blessed with 6 children (Butar-Butar, 2017)
Abidah, the first daughter of Sheikh Ma'shum bin Ali married Mahfud Anwar (son of
K.H. Anwar, founder, and leader of the Paculgowang Islamic Boarding School, Jombang).
Mahfudz Anwar also inherited his father-in-law's expertise in astronomy. In 1913 AD, Shaykh
Ma'shum bin Ali founded the Seblak Islamic Boarding School with an area of about 2 hectares.
One of the sciences taught in this pesantren is astronomy. Among the students studying at this
pesantren is Zubair Salatiga (author of "al-Khulāshah al-Wafiyyah"). Ma'shum bin Ali's works
in the field of astronomy include ad-Durūs al-Falakiyah, Badīah al-Mītsāl, and Fath al-Qadīr
fī 'Ajā'ib al-Maqādīr.
In his work "ad-Durūs al-Falakiyyah", Shaykh Muhammad Ma'shum bin Ali put forward
his formulation and conception of the standard time of Isha and dawn. The discussion of the
two he gave the title "Miqdār Hisshah ash-Syafaq wa Hisshah al-Fajr" (Measure of the
Duration of Syafak and Duration of Dawn). According to him, Isha time is when the Sun is