Calculation Methods with same values and high latitude adjustments

tcorak

I have two separate burning questions but did not want to create two separate posts for them. I hope this is okay, if not, please let me know.

I try to understand how prayer calculation methods work, how they differentiate from each other, etc. Please excuse my ignorance in advance.

Why are there multiple methods with the same fajr and isha angles? What is the rationale behind it? They seem to produce the exact same prayer times. For example, 11. MUIS - Singapore, 17. JAKIM, and 20. Kementerian all have fajr: 20, isha 18, without any offset params so they do show the exact same prayer times for the locations I've tried so far. Can I really use one instead of another or something behind the scenes is different and I should be careful?
Why is the default latitudeAdjustmentMethod ANGLE_BASED? Shouldn't it be NONE by default? I see there is no NONE option. Why is that? Any details would be appreciated, since I still can't comprehend the high latitude adjustment stuff.

meezaan

tcorak

Different methods are from different authorities. They use angles they think are best - in some cases they are the same. So yes, as long as the angles are the same and there is no offset, you can use one in lieu of the other.
NONE is there for mathematical reasons, but it's not really used anywhere. When the default was NONE, every developer asked a question about why the timings were different from their local authority, or Islamic Finder, etc. etc.

Hope this helps.

Jundullah

meezaan
Salam, do you know if there is anyway to calculate Prayertime without Latitude?

meezaan

Jundullah 3laykum salaam. No, you need both co-ordinates, or use geocoding to get the co-ordinates from an address string.

Jundullah

meezaan I meant if there is any other way brother, like ip but IP is not accurate, is there any other methods?

meezaan

Jundullah The actual calculation requires co-ordinates and there is no way to circumvent that.

tcorak

I'm not sure why my post attracted unrelated questions, but I'll carry on.

For high latitude, in order to see the effect of the highLatitudeAdjustment methods, the place should have a high latitude value, and preferably, the date should be summer, right? Otherwise, for normal or low latitude places, the default ANGLE_BASED adjustment or other adjustment does not do anything, am I correct? Or probably API doesn't even bother applying it because the Fajr and/or Isha time is within the "safe" timing range?

I am testing various high-latitude locations, such as Helsinki, Finland. As I understand it, the API does not automatically determine which high-latitude adjustment method to use; it seems to default to ANGLE_BASED and gives the user a choice. I saw some other APIs that automatically suggest one-seventh or middle of the night based on the latitude value, do you know or apply any recommendation to choose the method based on latitude or other variables?

meezaan

tcorak

tcorak I'm not sure why my post attracted unrelated questions, but I'll carry on.

👆️ is a vast subject, so let's not explore it and carry on, indeed 🙂.

For high latitude, in order to see the effect of the highLatitudeAdjustment methods, the place should have a high latitude value, and preferably, the date should be summer, right? Otherwise, for normal or low latitude places, the default ANGLE_BASED adjustment or other adjustment does not do anything, am I correct? Or probably API doesn't even bother applying it because the Fajr and/or Isha time is within the "safe" timing range?

Yes, you are right. I recommend you read - http://praytimes.org/wiki/Prayer_Times_Calculation. The AlAdhan API is based on this.

I am testing various high-latitude locations, such as Helsinki, Finland. As I understand it, the API does not automatically determine which high-latitude adjustment method to use; it seems to default to ANGLE_BASED and gives the user a choice.

Yes.

tcorak I saw some other APIs that automatically suggest one-seventh or middle of the night based on the latitude value, do you know or apply any recommendation to choose the method based on latitude or other variables?

I would venture a guess and say if you move beyond the sub-tropics, you'll almost definitely need to apply a method. I prefer Middle of the Night for it's simplicity, but there's no correct answer here. Local ulema or mosques would decide (I hope), rather than relying on an API or app telling them what is right.

tcorak

meezaan Thank you so much for your thoughtful response. Last question for this year (still in 2024 here) 🙂

Rovaniemi, Findland (approx. 66.5026, 25.7289)
Timezone: Europe/Helsinki
Method: MWL
High Latitude Adjustment: Angle Based
Date: 15 June 2024

API:
https://api.aladhan.com/v1/timingsByCity/15-06-2024?city=rovaniemi&country=Finland&method=3
Fajr: 01:18, Sunrise: 01:18, Dhuhr: 13:18, Asr: 18:17, Magrib: 13:18, Isha: 01:18

MuslimPro:
https://prayer-times.muslimpro.com/en/find?coordinates=66.50394779999999%2C25.7293905&country_code=FI&country_name=Finland&city_name=Rovaniemi&date=2024-06&convention=MWL&asrjuristic=Standard&highlat=Angle
Fajr: 13:18, Sunrise: 13:18, Dhuhr: 13:18, Asr: 18:16, Maghrib: 13:18, Isha: 13:18

This seems weird. Fajr, Sunrise, and Isha seem to be 24 hours off, this can't be just a simple 12h-24h time mistake, can it be?

Any location above 65 latitude (which might be considered an extreme high latitude, I guess) is usually different even though the same calculation method and high latitude adjustment are used.

meezaan

tcorak It sure looks like 24/12 hour mistake.

I am sure MuslimPro makes some adjustment to match local mosques / authorities in some cases - they have a team (or a person, perhaps) for local verification.