Rozhen Observation Calendar

Which nights are best for a target over the coming weeks. The astronomy mark (darkness × altitude × Moon) is computed for every night; the weather and the overall mark exist only where Open-Meteo has a forecast (the next four days) or ERA5 history (past nights) — the rest is honestly blank.

Best nights for Seven Sisters: 08-31 (100), 09-01 (100), 09-02 (100), 09-03 (100), 09-04 (100) — by astronomy; check the weather when the night is within four days.

2038-08-18astronomy score per night — click a bar for that night2038-09-16

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-08-18 Wed	18	—	unknown	02:05–04:50 (marginal, 2.75 h)	72.5° 07:20	6.82	85%	48.7°
2038-08-19 Thu	17	—	unknown	02:00–04:55 (marginal, 2.92 h)	72.5° 07:15	6.88	77%	36.9°
2038-08-20 Fri	20	—	unknown	01:55–04:55 (marginal, 3.0 h)	72.5° 07:10	6.94	69%	25.4°
2038-08-21 Sat	26	—	unknown	01:40–04:55 (marginal, 3.25 h)	72.5° 07:05	6.99	60%	14.5°
2038-08-22 Sun	35	—	unknown	03:30–05:00 (good, 1.5 h)	72.5° 07:05	7.05	50%	7.4°
2038-08-23 Mon	45	—	unknown	02:15–05:00 (good, 2.75 h)	72.5° 07:00	7.11	41%	13.5°
2038-08-24 Tue	57	—	unknown	02:05–05:00 (good, 2.92 h)	72.5° 06:55	7.16	31%	24.6°
2038-08-25 Wed	69	—	unknown	01:45–05:00 (good, 3.25 h)	72.5° 06:50	7.22	22%	36.8°
2038-08-26 Thu	81	—	unknown	01:40–05:05 (good, 3.42 h)	72.5° 06:50	7.28	14%	49.4°
2038-08-27 Fri	88	—	unknown	01:40–05:05 (good, 3.42 h)	72.5° 06:45	7.33	8%	62.5°
2038-08-28 Sat	94	—	unknown	01:35–05:05 (good, 3.5 h)	72.5° 06:40	7.39	3%	76.1°
2038-08-29 Sun	96	—	unknown	01:30–05:10 (good, 3.67 h)	72.5° 06:35	7.45	0%	90.1°
2038-08-30 Mon	98	—	unknown	01:25–05:10 (good, 3.75 h)	72.5° 06:30	7.5	0%	104.3°
2038-08-31 Tue	100	—	unknown	01:20–05:10 (good, 3.83 h)	72.5° 06:30	7.56	3%	118.7°
2038-09-01 Wed	100	—	unknown	01:20–05:10 (good, 3.83 h)	72.5° 06:25	7.62	9%	133.2°
2038-09-02 Thu	100	—	unknown	01:15–05:15 (good, 4.0 h)	72.5° 06:20	7.67	17%	147.6°
2038-09-03 Fri	100	—	unknown	01:10–05:15 (good, 4.08 h)	72.5° 06:15	7.73	26%	161.4°
2038-09-04 Sat	100	—	unknown	01:05–05:15 (good, 4.17 h)	72.5° 06:10	7.78	37%	172.2°
2038-09-05 Sun	100	—	unknown	01:05–05:15 (good, 4.17 h)	72.5° 06:10	7.84	48%	166.6°
2038-09-06 Mon	100	—	unknown	01:00–05:20 (good, 4.33 h)	72.5° 06:05	7.89	60%	153.9°
2038-09-07 Tue	100	—	unknown	01:00–05:20 (good, 4.33 h)	72.5° 06:00	7.95	70%	140.6°
2038-09-08 Wed	100	—	unknown	00:55–05:20 (good, 4.42 h)	72.5° 05:55	8.0	79%	127.5°
2038-09-09 Thu	100	—	unknown	00:55–05:25 (good, 4.5 h)	72.5° 05:55	8.06	87%	114.5°
2038-09-10 Fri	100	—	unknown	01:00–05:25 (good, 4.42 h)	72.5° 05:50	8.11	93%	101.7°
2038-09-11 Sat	78	—	unknown	01:30–05:25 (good, 3.92 h)	72.5° 05:45	8.16	97%	89.1°
2038-09-12 Sun	60	—	unknown	02:50–05:25 (good, 2.58 h)	72.5° 05:40	8.22	100%	76.6°
2038-09-13 Mon	45	—	unknown	04:50–05:30 (good, 0.67 h)	72.5° 05:35	8.27	100%	64.4°
2038-09-14 Tue	33	—	unknown	00:30–05:30 (marginal, 5.0 h)	72.5° 05:35	8.32	98%	52.4°
2038-09-15 Wed	24	—	unknown	00:35–05:30 (marginal, 4.92 h)	72.5° 05:30	8.38	94%	40.5°
2038-09-16 Thu	19	—	unknown	00:30–05:30 (marginal, 5.0 h)	72.5° 05:25	8.43	89%	28.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-08-18&days=30"
curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&days=30&format=csv" -o m31-calendar.csv

One row per night: score_astronomy always, score_weather / score only where a forecast or history exists (null otherwise, with weather_source saying which), best window, dark hours, Moon illumination and separation, transit. 7–60 nights. Errors: 400 with invalid_date or target_unresolved. Results are cached for six hours; calculation version 2026-10-10.1.