Harrow, United Kingdom
Qibla = 119 29 E (From True North)

SICM's time table is based on the extensive work done by the emminent astro-phisicist Dr. Mohammad Ilyas Ph.D(Adelaide), M.Sc. (Aligarh), FRMetS, FRAS as explained in his book A Modern Guide to Astronomical Calculations Of Islamin Calendar Times & Qibla. The difference in the magrib times should not be significant as all Shias add a few minutes to the sunset time to obtain the magrib time. Though a prominent Shia Mujtahid Mohammad Husain FazluAllah says magrib is same as sunset.

As for Imsak/fajr times SICM uses the well-known criteria of 18/16 degrees, i.e. when the sun is 18/16 degrees below the horizon. This criteria was well known to the muslim astronomers of the past and cn be seen in the works of many past and present day muslim scholars.

Note: Ayatullah Seestani says 'The obligatory precaution is that as 'long as the redness in the eastern sky appearing after sunset has not passed 'overhead, Maghrib Namaz should not be performed.' This is based on ihtiyat '(precaution) to the one who feels that the sunset does not take effect except 'after the disappearance of that redness.
Ayatullah Fadhullah says 'Sunset 'takes effect when the sun's disk disappears from the horizon,' 'Thus one can 'at such a time say one's maghrib prayer, and also break his fast if one 'fasts'
Ayatullah Khui It is Ehtiyate Wajib to wait until the redness that appears in the eastern horizon after sunset has passed overhead
Shaykh Sudduq, 'Sunset (Maghrib) is validated by the fall of the Sun's disk
Shaykh Tusi Maghrib starts at the setting of the sun

Please do not hesitate to contact us if you need more details regarding SICM's timetable.

prayertimes@sicm.org.uk

May Allah guide us on the right path.