To: oif@umsu.ac.id
Subject: Request for Raw SQM Observation Data — Fajr/Isha Twilight Research Collaboration

Assalamu alaykum wa rahmatullahi wa barakatuh,

My name is Ali Camarata. I am an independent researcher working on an open-source project to build the largest empirical dataset of verified Fajr and Isha twilight observations worldwide. The goal is to develop data-driven models for Islamic prayer time calculation based on real human and instrument observations rather than fixed-angle assumptions.

I recently read Lubis, Nafilah & Jihad (2025) in Al-Hisab 2(4):215-229, which used SQM data from OIF UMSU for November 2024. The paper references your observatory's continuous SQM monitoring program running since 2016-2017.

I am writing to ask whether OIF UMSU would be willing to share raw per-night SQM observation data from your Medan site (3.595 N, 98.672 E) for the years 2016-2024. Specifically, I need:

- Date of each observation night
- Local time when dawn brightness first exceeded the night baseline (Fajr onset)
- Local time when evening brightness dropped below the twilight threshold (Isha onset), if recorded
- Sky condition notes (clear, cloudy, etc.) for each night

Even a simple CSV or spreadsheet with date, Fajr time, and Isha time columns would be extremely valuable. The data would be used in an open-source research project (MIT licensed) with full attribution to OIF UMSU and the relevant researchers.

Our project repository: https://github.com/acamarata/pray-calc-ml
Current dataset: 4,200+ Fajr and 19 Isha verified observation records from 140+ sites worldwide.

Your data from Medan would be particularly valuable because:
1. It spans multiple years at a single equatorial site
2. It documents urban light pollution effects on twilight angles
3. North Sumatra is underrepresented in global twilight datasets

Please let me know if this collaboration is possible. I am happy to share our dataset and findings in return.

Jazakallahu khairan,
Ali Camarata
alisalaah@gmail.com
