• Defintion of the prayer times
• Principles for taqdir
  

• Physical aspects
  
• Astronomiical tables
  
• Compensation for refractionen
• Refraction at various latitudes within Sweden
  
• Shuruq and Maghrib in Islamic prayer time tables
  

• Astronomical measures of twilight
  
• Relation between fiqh definitions and astronomical angles
  
• Angles obtained from twilight observation
  

• Length of the period depending on definition
  
• Implementation of taqdir
  

• Comparison between manipulated and original times
  
• Construed times of Fajr during Ramadan
  
• Conclusion

www.birka.st

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Fajr (dawn):

1. al-fajr al-kadhib (false dawn): One may sometimes observe a vertical light on the sky before actual dawn. This was termed in the Hanafi madhhab "false dawn".
   
   
2. al-fajr al-sadiq (true dawn): the time when light can first be seen at the horizon, which then spreads horizontally. This is the beginning time for the Fajr prayer in the four madhahib.
   

Shuruq (sunrise) is defined as the time when the upper edge of the sun disk first becomes visible at the horizon.

Zhuhr (noon): The time for the zhuhr prayer begins when the entire sun disk has passed a vertical line suspended from the highest point of the sun during a day.

Asr (afternoon): There are two opinions regarding the start of Asr prayer:

1. The time when the shadow of an object exceeds its noon shadow by once its own length. This is the definition according to the Shafi`i, Maliki and Hanbali madhhab, and it was the opinion of the two companions of Imam Abu Hanifa (Imam Muhammad and Qadi Abu Yusuf), rahimahum Allah ajama'in.
   
   
2. The time when the shadow of an object exceeds its noon shadow by twice its own length. This was the opinion of Imam Abu Hanifa, and it is fatwa in the madhhab.

Maghrib (sunset) is defined as the time when the entire sun disk has disappeared below the horizon.

Isha (night) has two definitions:

1. After passing of the red twilight (al-shafaq al-ahmar), i.e. is when the red sunset light disappears and a white layer if light remains at the horizon. This is the start of Isha according to the two companions of Imam Abu Hanifa⁵, and this is also the definition in the other madhahib.
   
   
2. After passing of the white twilight (al-shafaq al-abyad), i.e. the time when the white layer of layer disappears and complete darkness overtakes. This was the opinion of Imam Abu Hanifa⁵.
   

Principles of taqdir

At high latitudes, there are periods during the summer when the prayer times do not exist accoriding to the above definitions.

Physical aspects
Any  calculation model needs to take into account the following factors:

• (a) the passing of the entire sun disk through the horizon
  
• (b) refraction through the atmosphere
  
• (c) the observer's position above sea level.
  

The apparent sun radius (as viewed by an observer on earth) has a radius of 0.16 arc minutes ( 0.267° in decimal form). This is independent on location on earth. Refraction however depends on latitude, as well as on the temperature profile through the atmosphere. The effect of elevation above sea level is complex and is not discussed in this version of the paper.

Astronomical tables
Astronomical sunrise/sunset depression from zenith is 90°. In the Islamic context, the depression from the horizon is preferred, i.e. sunrise/sunset is when the sun is depressed 0° from the horizon. At this point, one would see the center of the sun disk passing through the horizon, when standing at a free horizon at sea level - if there were no atmosphere surrounding earth. However, sun rays passing through the atmosphere are deviated, due to the refraction of the air. Therefore the observer will see sunrise a little earlier and sunset a little later than the times calculated.

Most astronomical and metrological time tables compensate for this by adding a standard angle of 0.833°.

The Swedish Metrological Institute, SMHI [Ref, data]  and Astronomisk kalender [Ref, data] sunrise and sunset as the astronomically compute time when the center of the sun disk is at the horizon, adjusted with an angle of 3.4´ (0.57°). It is not clear it this is meant to compensate for refraction alone or also for the passage of the disk through the horizon.

The astronomical calendar "Den Svenska Almanackan" uses a compensaiton of 0.833°, which is the international standard used also US Naval Observatory [Ref, data] and other observatories around the world. This is meant to compensate by 0.16´ (0.267°) for the apparent radius of the sun, plus 0.34´ for refraction, summing up to 0.5` (0.833° in decimals).

Compensation for refraction
At high latitudes, refraction has an essential effect on the observation of sunrise and sunset. It is therefore necessary to apply a more refined method than that used in presently available tables.

Most Islamic prayer time tables adopt the international standard of 0.57°, which was suggested by Bessel in 1823, which is not adequate at high latitudes. Tables published by IKUS for Scandinavia use an adjustment of 1.73°, which applies to extreme latitudes.

In Birka we have implemented a simple empirical model for the variation of refraction with latitude (see section on Refraction):

• This is valid for all latitudes from 0° to 75° (the latitude of Norway's furthermost point is 70°, northern Greenland is at 75°, the North Pole at 90°).
  
• After adding 0.27° to compensate for the sun's apparent radius, the total compensation for Sweden will vary between 1.0° and 1.34°.
• The compensation 0.833 is valid at latitude 49°. It is approximately valid in London.
  

Refraction aangles for locations at different latitudes
The table below shows the difference in sunset times obtained with and without refraction compensation at different latitudes. We can see that the standard compensation of 0.833° adds 4-5 minutes to sunset time. This is valid in London. In Stockholm the effect is 10 minutes, and in northern Sweden up to half an hour and more!

Location	Latitude	Compensation for		Effect on calculated sunset time
		refraction	refraktion plus sun radius	June, 21	Sept, 21	Dec, 21
Riksgränsen	68.4°	1.29°	1.56°	*	14 min	**
Kiruna	67.9°	1.25°	1.52°	*	14 min	**
Luleå	65.6°	1.11°	1.38°	***	11 min	29 min
Skellefteå	64.8°	1.07°	1.34°	39 min	10 min	23 min
Umeå	63.8°	1.02°	1.29°	26 min	9 min	19 min
Sundsvall	62.4°	0.97°	1.24°	18 min	8 min	15 min
Gävle	60.7°	0.89°	1.16°	13 min	7 min	12 min
Stockholm	59.3°	0.84°	1.11°	11 min	7 min	11 min
Göteborg	57.7°	0.79°	1.06°	9 min	6 min	9 min
Malmö	55.6°	0.73°	1.00°	7 min	5 min	7 min
London	51.5°	0.63°	0.90°	5 min	4 min	5 min
New York	40.8°	0.43°	0.70°	3 min	3 min	3 min
Damascus	33.5°	0.32°	0.59°	2 min	2 min	2 min
Makka	21.5°	0.20°	0.47°	1 min	1 min	1 min

 

Islamic prayer time tables
We conclude from the above that the compensation used in the current prayer time tables is not adequate. The table below shows the calculated time for Maghrib varies depending on the compensation applied.

Sunset on June, 15, 2009	Makka Lat 21°	London Lat 51°	Stockholm Lat 59°	Skellefteå Lat 65°
0.267° (sun radius only)	18:02	21:15	21:58	23:08
0.567° (Astronomisk. almanacka)	18:03	21:17	22:02	23:17
0.833° (US Naval - Bessel 1823)	18:04	21:19	22:06	23:25
0.47 - 1.0 - 1.11 - 1.31 Birka f(Lat))	18:02	21:20	22:09	23:45
1.7 (IKUS)	18:08	21:27	22:17	0:05

Taking Birka as the accurate norm, we see that tables applying the model of Bessel give Maghrib times up to 20 minutes ahead of the its time, while the IKUS model leads to Maghrib times up to 20 minutes past its time.

Astronomical measures
Astronomers use the following measures of darkness:

• Civil twilight lasts until the sun is 6° below the horizon. At good weather conditions, largest stars will then appear on the sky.
  
• Nautical twilight lasts until the sun is 12° below the horizon. After that one can no longer distinguish objects at sea.
  
• Astronomical twilight lasts until the sun is 18° below the horizon. After this, no sunlight reaches the oberver.
  

Relation between fiqh defintions and astronomical angles
According to the Egyptian Fatwa Authority (Fatwa No. 200750), the difference between the disappearance of the red and the white twilight corresponds to an angel of 3°.

Most Islamic prayer tie tables relate the fiqh definition of Fajr and Isha to an angle between 15° and 20°. Some commonly quoted value are shown below.

Fatawa	Fajr (Imsak)	Isha (red twilight)	Isha (vhite twilight)
Uthmani fatawa [1]	19°	17°	19°
Egyptian General Authority of Survey [2]	19.5°	17.5°
Univ. Islamic Sciences, Karachi [3]	18°	--	18°
Muslim World League [5]	18°	18°
ISNA [6]	18°	18°

• [1] Endless Bliss
• [2], [3] Quoted from Islamicfinder;
• [5] According to a fatwa of the Muslim World League (Rabita), 9th konference 1406 H (March 1996)., reiterated in  2003 nd 2007, the angel for Isha should be 17°. According to a new descision, taken in Belgium in September 2009, the angel 18° is now used. (Rabita in Sweden does not flollow any of these methods, see below.)
• [6] Update (Sept 7, 2009): According a message by Dr. Muzammil H. Siddiqi, chairman of the Fiqh Council of North America, "The correct Fajr time begins when sun is 18 degrees below  the horizon. Inshallah, we shall correct the information given in the name of ISNA". The same angle is also recommende for Isha. The messages were sent out to ICOP Mainling List on Sept. 5 and Sept 7, 2009. Hence the angle quoted by IslamicFinder is incorrect.

Published tables	Fajr	Isha
IKUS1	20°	18°
Islamic Academy1, 2	18°	18°
Islamiska Förbundet i Sverige (Swedish branch of Rabita)1, 3	14.7° winter time	13.7° winter time

1. Angles are obtained as best fit to published time tables.
2. Islamic Academy's tables are based on the recommendation of University of Islamic Sciences in Karachi, then adding a few minutes for safety.
3. The tables from Islamiska Förbundet (Swedish branch of Rabita) used to employ the ISNA recommendation, but recently switched to a new claculation model. We have not been able to find any detialed information about the new model. In summer time no fix angle is used.
   

At high latitudes, the computed length of the twilight interval (from Maghrib to Isha) is increasingly sensitive to the angle used for Fajr and Isha, as seen in the table below:

Ort	Latitud	12°	15°	18°
Riksgränsen	68.4°	-	--	--
Luleå	65.6°	3:17 min	--	--
Sundsvall	62.4°	2:19 min	3:28 min	--
Stockholm	59.3°	1:56 min	2:38 min	3:42 min
Göteborg	57.7°	1:48 min	2:23 min	3:10 min
Malmö	55.6°	1:38 min	2:09 min	2:46 min
London	51.5°	1:25 min	1:51 min	2:18 min
Makka	21.4°	0:52 min	1:06 min	1:18 min

 Time between nominal sunset (0.267°, i.e. no refraction comepnsation) och twilight end
  on August, 21, 2009, depending on the definition of twilight

In Makka, on August 21, the difference between 15° and 18° corresponds to a time difference on only 12 minutes, while in Stockholm it corresponds to one hour's difference (in the north of Sweden, twilight does not end at this date).  From there we see that it is most important to use an accurate model for high latitudes. Such a model must be based on actual observation of the phenomena described by the fuqaha.

Angles deduced from observation of dawn and dusk
How to relate eye observation of Fajr and Isha to the angles used in calculations, and what needs to be considered in order to make generally valid observations - this is discussed in detailed in the section  Observations. Below is a summary of angles obtained from various observations:

al-shafaq al-ahmar 9-15° al-shafaq al-abyad 14-18° al-fajr al-sadiq 14-19°

These values need to be taken with great caution, as many observations are likely to be affected by light contamination, making it impossible to observe a really dark sky - see the section Physical measures of darkness. The conservative route is to use the higher values in each category.

"Persisting twilight" means that Isha and Fajr times do not exist according to their fiqh definitions. This occurs at high latitudes for a longer or shorter period during summer. This phenomenon is mentioned in the early Hanafi fiqh literature. The computed length of this period varies with latitude, and depends on which angles are adopted for Fajr and Isha.

Approaching the polar circle, sunset also disappears and the sun is stil visible at midnight (midnight sun). This is not mentioned in the classical fiqh literature.

Length of the period depending of twilight definition
The table below shows beginning and end of the persisting twilight period for locations at various latitudes, depending of which angle is used for Isha.

Location	Latitude	Beginning				End
		18°	15°	12°		12°	15°	18°
Riksgränsen	68.4°	29mar	6apr	13apr		27aug	4sept	12sep
Luleå	65.6°	6apr	14apr	22april		19aug	28aug	5sep
Sundsvall	62.4°	14apr	23apr	3maj		9aug	18aug	27aug
Stockholm	59.3°	23apr	3maj	14maj		28jul	8aug	18aug
Göteborg	57.7°	28apr	9maj	21maj		21jul	2aug	13aug
Malmö	55.6°	5maj	17maj	3juni		7jul	25jul	6aug
London	51.5°	22maj	--	--		--	--	20jul
Paris	48.9°	12jun	--	--		--	--	29jun

If, for instance, the angle 18° is used for Isha (corresponding to the end of the white twilight), the period in which Isha does not occur in Stockholm lasts from April 23 to August 18, and persistent twilight occurs down do latitude 49° (Paris). If instead 15° is used for Isha, the period will be three weeks shorter in Stockholm, and it will not occur at all south of latitude 51.5° (London).

Implementation of taqdir
When prayer times do not occur according to their definition, one may construe them (taqdir) according to the directions given by fuqaha. Taqdir is only to be used a way out when this is necessary, i.e. within the period when no time can be observed, not outside that period.

The Shafi'i madhhab rules the principle of "aqrab al-bilad", which meabs that prayer times are taken from the nearest location where the times still exist. The span of time between Maghrib and Isha at that location is added to the local Maghrib time. However, if this is applied on a day-to-day basis, the location that lent its time will soon lose it as well, so one has to move further south to find a new location where the times exist and repeat the same procedure [Ref]. Hence in practice, this implementation "aqrab al-bilad" amounts to setting Isha close to midnight (between sunset and sunrise) for the entire period.

In the Hanafi madhhab, if the white twilight is normally used, the red twilight can be used during the critical period, if it exists, since it is a valid alternative in the madhhab. When the red shafaq also persists, different methods of taqdir have been suggested by recent 'ulama in the Hanafi madhhab:

1. Adding a fixed time interval Maghrib:
   Time intervals between 57 minutes and 2 hours have been suggested.
   
   For reference, Sheikh Ibn Uhtaymin (Hanbali madhhab) [Ref] suggested to use to time interval betwen Maghrib and Isha in Makka. In summer. this interval is between 77 and 88 minutes. Hence, adding 90 minutes to the local Maghrib time  would satisfy his criterion. (Note that the fatwa only allows this when the time is non-existent.)
   
   However, this method collapses at high latitudes, as soon as the time difference from sunset to midnight becomes less than the suggested time interval.
   
   
2. Aqrab al-ayyam (the nearest day):
   The  time for the day just before the prayer time expired is used [Ref] - In practice this amounts to setting Fajr and Isha at midnight (between sunset and sunrise).
   
   IKUS and Islamic Academy apply this to Fajr in their time tables for Scandinavia.
   
   
3. Aqrab al-bilad (nearest location):
   This principle can be applied in two different ways, depending on what is meant by "nearest location":
   
   1. the nearest location where the prayer time can be observed at that specific date
   2. nearest location where the prayer time can be observed all year round
      
   
   Applying (a), as in the method described above for the Shafi'i madhhab, results in setting Fajr and Isha near midnight throughout the critical period, i.e. the same as in "aqrab al-ayyam".
   
   Applying (b) would mean applying the prayer times from a location at the same longitude, but far enough south to get the prayer times all year round.
   
   Using 18° for normal Isha times, this amounts to using the Isha and Fajr times at latitude 48.5, which is the most northern location at which the sun goes below 18° thorughout summer. Stockholm, located at (59, 18), would then use the Isha and Fajr times  at coordinates (48.5, 18) in Horne, Slovakia as Aqrab al-Bilad.
   
   This simple method works surprisingly well, and can safely be used all the way up to where Mahgrib disappears., i.e. up to the 65th latitude.
   
   If one decides to define the standard Isha depression as 15°, it is necessary to find the furthest location where Isha exist throughout summer according to this definition, and use that as Aqrab l-Bilad. This is a latitude of 51.5.
   
   If one defines the standard Isha depression as 17°, aqrab al-Bilad is at latitude 49.5.
   
   
   
4. Half of the night, or a third, or a seventh:
   Isha is obtained by adding the corresponding fraction of the night to the Maghrib time.
   

A combination of 3 and 1 is suggested by Nuh Keller in "The Reliance of the Traveller", namely to add the amount of time between  Maghrib and Isha in the "nearest city" to the time of Maghrib in one's own city (and similarly for Fajr). However, this method crashes at high latitudes (e.g. in Sweden), and  produces Isha times that are later than the calculated Fajr times!  This is because the time between Maghrib adn Isha is not 90 minutes as assumed, but closer to 3 hours, resulting in Isha times past midnight and Fajr times before midnight.

A combination of 3 and 4 above was suggested by MWL 2003 one could use the night portion corresponding to the nearest loction  where persistent twilight does not occur (defined as 48° latitude), calculate the corresponding  local night portion, and add this to the local Maghrib time. A similar algorithm was implemented by ICOP 2009, where the estimate is based on the local average night portion under normal conditions.

Conclusion:
The methods that can be practically applied at all locations up to the 65th laittude are the following:

1. Replacing the Isha/Fajr times with those at the 48th latitude
   
2. Using a variable night portion based e.g. on the 48th latitude
   
3. Using a fix night portion (e.g. midnight, 1/3, 1/7 or the local mean under normal conditions)

Note regarding the length of the night:
In Hanafi fiqh, the night is defined as the time between sunset and sunrise.In Maliki and Shafi'i fiqh, however, night means the time between sunset and Fajr, which poses the problem of estimating Fajr in the first place, in order to obtain the length of the night. If, for simplicity, the time from Fajr to Shuruq is taken to be equal to the time from Maghrib to Isha, and n denotes the part of the night to be computed, then

        1/n _{maghrib-shuruq} =1/(n+1) _maghrib-fajr

For example:

• 1/2 of the night from sunset to sunrise corresponds to 1/3 of the night from sunset to dawn
• 1/3 of the night from sunset to sunrise corresponds to 1/4 of the night from sunset to dawn
• 1/6 of the night from sunset to sunrise corresponds to 1/7 of the night from sunset to dawn

Some Islamic prayer time tables do not apply any of the above principles, instead they use other interpolation methods. For instance,

• IslamicFinder uses a method they name "angle based", which means that Fajr and Isha are calculated as the part of the night corresponding to the respective angle / 60. Using 15° for Isha for instance, the program will calculate the time for Isha as 15/60th = 1/4th of the night from sunset to sunrise and add it to Maghrib.
  
  
• Rabita uses a special method devised by their organization, where Isha is taken as 1/3rd of the night from sunset to sunrise at midsummer, but varies during the rest of the period.
  

The problem with these methods is that they are used even outside the critical periods, when there is no valid reason for construing prayer times -- see Criticism of current prayer time tables.

Many prayer time tables use some form of estimate (taqdir) for Fajr and Isha times in locations where these times to do not exist for a  limited period during summer. However, in order to get a smooth transition to the prayer times in winter, the time table is "padded" in a way that it contains construed times for the entire period between the equinoxes. In other words. construed times are tabulated for dates when the prayer times exist according to their fiqh definition. Ramadan year 2008 and onwards is included in the period where fallacious times for Fajr are given.

This problem was pointed out by the Cambridge Prayer Time Project 2004⁴, but unfortunately does not seem to have received the attention it deserves. Below we will illustrate the problem for three specific cases.

Comparison between manipulated and real times for some common prayer timetables
In order to expose the problem, we have plotted

• Fajr times issued by Rabita (Islamiska Förbundet) for Stockholm (Latitude 59.3) year 2009
• times computed by Islamic Finder ("angle based") for Stockholm year 2009
• times tabulated by Hizbul Ulama in Blackburn (Latitude 53.7), perennial

Each set of data is compared to unmodified times computed with Birka, using a fix angle of 14.7°, which corresponds to Rabita's table in winter, as well as with Blackburn tables in spring and autumn.

• On the vertical axis is time a.m.
  
• The red lines are al-fajr al-sadiq computed with Birka using 14.7°.
• Light-blue regions indicate the periods of persistent twilight (i.e. Fajr does not exist)
  
• The green, blue and purple lines are respectively for
  
• Rabita (IFS) (interpolation method: special algorthm)
• Islamic Finder (interpolation method: "angle based")
  
• Hizbul Ulama (interpolation method: hand-made)
• The yellow regions indicated indicate those periods of the year during which construed Fajr times are given, despite the fact that the real al-fajr al-sadiq can be observed.
  

The jumps in the curves are due to transition to and from summer time light saving.

Construed Fajr times during Ramadan
We see that the curve of Rabita (IFS) fits 14.7° during winter time. For this angle, the period of persistent twilight lasts from May 5 to August 9, i.e. this is the period during which al-fajr al-sadiq cannot be observed. However the method of Rabita (IFS) does not return to the Fajr definition of 14.7° when the critical period is over. It continues to produce artificial values for 7 months of the year, from March 1 until September 30!

Ramadan year 1430 H. (2009) is from August 20 to Sept 19. For this month, the time difference between the Fajr time given by IFS´s and al-fajr al-sadiq range from 10 to 50 minutes in Stockholm. Further north, it is even more. If a person begins his fast at the Fajr-time given by IFS, it means that he is eating long after al-fajr al-sadiq, and his fast may not be valid.

Islamic Finder computes prayer time tables worldwide, that can easily be linked into any home page. Twilight angles can be set by the user, or one may use one of the preset schemes that are named "Egyptian Authority of Survey", "Islamic University of Karachi" etc. However, regardless of what settings are used, the program will invariably apply the interpolation algorithm called "angle based" (explained above). It cannot be switched off, and it is not limited to the period of persistent twilight. It continues to produce artificial values for Fajr until these latter coincide with the true values, i.e. from April 13 to August 29. It should be pointed out that this procedure is not sanctioned by Fatwa authorities in Egypt or Karachi, they are entirely a product of IslamicFinder's calculation scheme.  In Ramadan 1430 H. (2009) the time difference between true Fajr and unduly construed Fajr times is up to 24 minutes.

These interpolation methods used by Rabita and IslamicFinder are not acceptable, and may lead to Muslims starting their fast too late.

Hizbul Ulama in Blackburn made a yearlong study observing for each day sunrise, sunset and morning and evening twilights. On the basis of these observations, the constructed a prayer time table for Blackburn. Rejecting categorically astronomical angles as a basis for prayer times calculation, they calculated the difference between Maghrib and Isha, and between Fajr and sunrise, observed in Blackburn, and added these to local sunrise/sunset times in other cities. In this way they constructed prayer time tables for various locations in the UK. - The third graph in the above figure compares the timetable for Blackburn with times computed with Birka for the angle 14.7°. We may first of all note that the coincidence is very good for the winter months - contrary to the statements of Hizbul Ulama, who state that no fix angle fits their data. - In summer time, when the true dawn does not take place, the Blackburn tables contain values for the time when light has spread all along the horizon, which corresponds in their case to an angle of 8.5°. Then the curve is "smoothed out" so as to avoid gaps. This last procedure spreads out the artificial values over the whole period from March to September. In other words, during these transition periods, interpolated values are given in the tables, even where al-fajr al-sadiq was actually observed!


Summary

• At all locations above latitude 48, Fajr and Isha do not exist according to their fiqh definition for a longer or shorter period in summer. This is known as "persistent rwilight".
  
  
• Prayer time tables issued by Hanafi institutes in most cases don't give any time for Isha, and if time is given for Fajr, it is midnight.
  
  
• Prayer time tables where taqdir is applied for non-existing times do not limit this to the period of persisting twilight, but continue applying it over 6-7 months of the year.
  
  
• Although taqdir as such is permitted, or in the Shafi'i madhhab even necessary during the periods of persistent twilight, we don't see any fiqhi justification for applying it outside this period of time, and must be regarded as invalid.
  
  
• This problem becomes most relevant during Ramadan, when many Muslims, following the Sunna, get up for Suhur at a time near Fajr.
  
  
• The time tables of Rabita and IslamicFinder give unduly construed values of Fajr during Ramadan 2009 in Sweden. If these times are followed, the fast will begin too late. For Stockholm, the difference can be as much as 50 minutes, and for locations further north even more.
  
  
• In UK, this does not affect Ramadan 2009, but it will affect Ramadan 2010.
  
  
• The Birka time tables apply taqdir only during the periods where this is allowed/necessary, and marks the estimated values by putting them into brackets. As a result, there is no smooth transition, however, this is the correct approach.

1. It is not clear if SMHI is taking account of the sun passage over the horizon or not.

2. The principle of "Aqrab al-ayyam" was established for the Hanafi madhhab by Hazrat Thanvi in Imdadul Fatawa Vol 1, p 98 (quoted by Y. Miftahi, p. 111)

3. "With regard to the issue of First Light vs Tabayyun, Mufti Saeed Ahmed Palanpuri with the support of Mufti Mohammad Amin and Mufti Abdur-Rauf says that there is disagreement in Hanafi Fiqh on whether the beginning of Fast is from Fajare Haqiqi or from its Tabayyun (i.e. when the light has spread along the horizon). Whilst the beginning of the Fast at First Light is the safer of the two, the time of Tabayyun allows ease and is permissible. This ruling is supported by Mufti Saeed Ahmed who referred to Hazrat Molana Binori’s Marifuss Sunan, Volume 5, Page 323, which itself is based on Fatawa Hindiyah, the Fatawa Alamghiri, which uses Halwani, Al Muhiti and Khazanatul Fatawa in support of this ruling." (Y. Miftahi p. 84)

4. "The Cambridge Prayer timetable Project uses the “Daruri” shariah rules, which indicate that if anything is permitted under “extreme necessity” the permission should only be confined within that terminology and not beyond. And those exceptional cases should not be generalised. Accordingly, if we have to estimate some prayer times – when the Shariah phenomena is difficult to implement and interrupted or absent, we should only confine our estimation under these circumstances. Here in Britain, the shariah phenomenon (i.e., the absence of persistent twilight) is present for about for about eight months. We therefore need only to estimate, change or adjust any of the prayer times for the period when the shariah phenomenon is absent or difficult to implement. In some prayer time-tables the timings for prayers are changed all year round without any valid reason. We only need to estimate the prayer timings if the shariah phenomena is absent or difficult to implement. We follow and abide by the Islamic shariah’s rules in order to determine the prayer timings in the period where the shariah phenomena is stable, consistent and is implement able."  (The Cambridge Prayer Timetable Project, 2004, p. 5 - emphasis of this author)

5. There is ikhtilaf in the Hanafi madhhab regarding the beginning of Isha. For a discussion of the subject see this link, or the summary given by (Dar al-Ifta al-Misriyya, Fatwa No. 20070). The red twilight is taken as the fatwa in some of the basic fiqh texts of the madhhab (Nur al-Idah/Maraqi al-Falah/Imdad al-Fattah, Mukhtasar al-Quduri/al-Lubab), while the white twilight is preferred in Radd al-Muhtar. There is agreement that the best thing is to avoid praying between the disappearance of the red and white twilights, in order to avoid going against any of the opinions.

6. Nuh Keller writes in the Appendix of "The Reliance of the Traveller", p. 895 (Section w19.2):

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