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: 09-20 (100), 09-21 (100), 09-22 (100), 09-23 (100), 09-24 (100) — by astronomy; check the weather when the night is within four days.

2039-09-20astronomy score per night — click a bar for that night2039-10-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2039-09-20 Tue	100	—	unknown	00:05–05:35 (good, 5.5 h)	72.5° 05:10	8.62	8%	150.6°
2039-09-21 Wed	100	—	unknown	00:00–05:35 (good, 5.58 h)	72.5° 05:05	8.68	16%	164.3°
2039-09-22 Thu	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 05:05	8.73	25%	174.5°
2039-09-23 Fri	100	—	unknown	23:55–05:40 (good, 5.75 h)	72.5° 05:00	8.78	36%	165.2°
2039-09-24 Sat	100	—	unknown	23:50–05:40 (good, 5.83 h)	72.5° 04:55	8.83	47%	151.5°
2039-09-25 Sun	100	—	unknown	23:50–05:40 (good, 5.83 h)	72.5° 04:50	8.88	58%	137.6°
2039-09-26 Mon	100	—	unknown	23:45–05:45 (good, 6.0 h)	72.5° 04:45	8.93	69%	123.7°
2039-09-27 Tue	100	—	unknown	23:50–05:45 (good, 5.92 h)	72.5° 04:45	8.98	79%	109.9°
2039-09-28 Wed	100	—	unknown	23:55–05:45 (good, 5.83 h)	72.5° 04:40	9.03	87%	96.3°
2039-09-29 Thu	100	—	unknown	00:45–05:45 (good, 5.0 h)	72.5° 04:35	9.08	94%	82.8°
2039-09-30 Fri	73	—	unknown	02:20–05:45 (good, 3.42 h)	72.5° 04:30	9.12	98%	69.5°
2039-10-01 Sat	55	—	unknown	05:20–05:50 (good, 0.5 h)	72.5° 04:25	9.17	100%	56.4°
2039-10-02 Sun	35	—	unknown	23:30–05:50 (marginal, 6.33 h)	72.5° 04:25	9.22	100%	43.6°
2039-10-03 Mon	22	—	unknown	03:15–05:50 (marginal, 2.58 h)	72.5° 04:20	9.27	97%	31.1°
2039-10-04 Tue	21	—	unknown	23:25–05:50 (marginal, 6.42 h)	72.5° 04:15	9.32	93%	19.1°
2039-10-05 Wed	25	—	unknown	23:05–05:55 (marginal, 6.83 h)	72.5° 04:10	9.36	87%	8.2°
2039-10-06 Thu	34	—	unknown	22:50–05:55 (marginal, 7.08 h)	72.5° 04:10	9.41	80%	8.0°
2039-10-07 Fri	47	—	unknown	22:35–05:55 (marginal, 7.33 h)	72.5° 04:05	9.46	72%	18.6°
2039-10-08 Sat	60	—	unknown	22:25–05:55 (marginal, 7.5 h)	72.5° 04:00	9.5	64%	30.1°
2039-10-09 Sun	81	—	unknown	22:50–05:55 (good, 7.08 h)	72.5° 03:55	9.55	54%	41.8°
2039-10-10 Mon	88	—	unknown	22:45–06:00 (good, 7.25 h)	72.5° 03:50	9.59	45%	53.6°
2039-10-11 Tue	95	—	unknown	22:40–06:00 (good, 7.33 h)	72.5° 03:50	9.64	35%	65.7°
2039-10-12 Wed	100	—	unknown	22:40–06:00 (good, 7.33 h)	72.5° 03:45	9.68	26%	78.1°
2039-10-13 Thu	100	—	unknown	22:35–06:00 (good, 7.42 h)	72.5° 03:40	9.73	18%	90.8°
2039-10-14 Fri	100	—	unknown	22:30–06:05 (good, 7.58 h)	72.5° 03:35	9.77	10%	103.9°
2039-10-15 Sat	100	—	unknown	22:25–06:05 (good, 7.67 h)	72.5° 03:30	9.81	5%	117.4°
2039-10-16 Sun	100	—	unknown	22:20–06:05 (good, 7.75 h)	72.5° 03:30	9.86	1%	131.2°
2039-10-17 Mon	100	—	unknown	22:20–06:05 (good, 7.75 h)	72.5° 03:25	9.9	0%	145.4°
2039-10-18 Tue	100	—	unknown	22:15–06:05 (good, 7.83 h)	72.5° 03:20	9.94	2%	159.6°
2039-10-19 Wed	100	—	unknown	22:10–06:10 (good, 8.0 h)	72.5° 03:15	9.99	6%	172.7°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2039-09-20&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.