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: 01-21 (100), 01-22 (100), 01-23 (100), 01-24 (100), 01-25 (100) — by astronomy; check the weather when the night is within four days.

2030-01-13astronomy score per night — click a bar for that night2030-02-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-01-13 Sun	45	—	unknown	18:55–02:05 (marginal, 7.17 h)	72.5° 20:35	11.27	71%	10.6°
2030-01-14 Mon	31	—	unknown	18:55–01:50 (marginal, 6.92 h)	72.5° 20:30	11.25	80%	2.4°
2030-01-15 Tue	23	—	unknown	18:55–01:30 (marginal, 6.58 h)	72.5° 20:30	11.22	87%	13.6°
2030-01-16 Wed	19	—	unknown	18:55–20:35 (marginal, 1.67 h)	72.5° 20:25	11.2	93%	25.8°
2030-01-17 Thu	24	—	unknown	19:00–22:35 (marginal, 3.58 h)	72.5° 20:20	11.18	97%	38.2°
2030-01-18 Fri	38	—	unknown	19:00–01:05 (marginal, 6.08 h)	72.5° 20:15	11.16	99%	50.9°
2030-01-19 Sat	57	—	unknown	19:00–20:00 (good, 1.0 h)	72.5° 20:15	11.13	100%	63.8°
2030-01-20 Sun	75	—	unknown	19:00–22:35 (good, 3.58 h)	72.5° 20:10	11.11	98%	77.0°
2030-01-21 Mon	100	—	unknown	19:00–00:05 (good, 5.08 h)	72.5° 20:05	11.08	94%	90.4°
2030-01-22 Tue	100	—	unknown	19:05–00:50 (good, 5.75 h)	72.5° 20:00	11.05	88%	104.0°
2030-01-23 Wed	100	—	unknown	19:05–01:00 (good, 5.92 h)	72.5° 19:55	11.03	80%	117.7°
2030-01-24 Thu	100	—	unknown	19:05–00:55 (good, 5.83 h)	72.5° 19:55	11.0	70%	131.6°
2030-01-25 Fri	100	—	unknown	19:05–00:55 (good, 5.83 h)	72.5° 19:50	10.97	59%	145.6°
2030-01-26 Sat	100	—	unknown	19:10–00:55 (good, 5.75 h)	72.5° 19:45	10.94	48%	159.6°
2030-01-27 Sun	100	—	unknown	19:10–00:50 (good, 5.67 h)	72.5° 19:40	10.91	37%	173.6°
2030-01-28 Mon	100	—	unknown	19:10–00:50 (good, 5.67 h)	72.5° 19:35	10.88	26%	171.7°
2030-01-29 Tue	100	—	unknown	19:10–00:45 (good, 5.58 h)	72.5° 19:35	10.85	17%	157.6°
2030-01-30 Wed	100	—	unknown	19:10–00:40 (good, 5.5 h)	72.5° 19:30	10.82	9%	143.5°
2030-01-31 Thu	100	—	unknown	19:15–00:35 (good, 5.33 h)	72.5° 19:25	10.79	4%	129.4°
2030-02-01 Fri	100	—	unknown	19:15–00:30 (good, 5.25 h)	72.5° 19:20	10.76	1%	115.6°
2030-02-02 Sat	100	—	unknown	19:15–00:30 (good, 5.25 h)	72.5° 19:15	10.72	0%	101.9°
2030-02-03 Sun	100	—	unknown	19:15–00:25 (good, 5.17 h)	72.5° 19:15	10.69	2%	88.6°
2030-02-04 Mon	100	—	unknown	19:20–00:20 (good, 5.0 h)	72.5° 19:10	10.65	6%	75.5°
2030-02-05 Tue	100	—	unknown	19:20–00:15 (good, 4.92 h)	72.5° 19:05	10.62	12%	62.8°
2030-02-06 Wed	93	—	unknown	19:20–00:15 (good, 4.92 h)	72.5° 19:00	10.58	19%	50.4°
2030-02-07 Thu	86	—	unknown	19:20–00:10 (good, 4.83 h)	72.5° 19:00	10.55	27%	38.2°
2030-02-08 Fri	77	—	unknown	19:20–23:50 (good, 4.5 h)	72.5° 18:55	10.51	36%	26.3°
2030-02-09 Sat	60	—	unknown	19:25–23:40 (good, 4.25 h)	72.5° 18:50	10.48	45%	14.5°
2030-02-10 Sun	45	—	unknown	20:25–21:10 (good, 0.75 h)	72.5° 18:45	10.44	54%	3.2°
2030-02-11 Mon	33	—	unknown	19:25–00:10 (marginal, 4.75 h)	72.5° 18:40	10.4	64%	9.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-01-13&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.