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: 01-25 (100), 01-26 (100), 01-27 (100), 01-28 (100), 01-29 (100) — by astronomy; check the weather when the night is within four days.

2035-01-20astronomy score per night — click a bar for that night2035-02-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2035-01-20 Sat	22	—	unknown	19:00–01:05 (marginal, 6.08 h)	72.5° 20:10	11.11	88%	22.9°
2035-01-21 Sun	24	—	unknown	19:00–22:55 (marginal, 3.92 h)	72.5° 20:05	11.09	95%	36.9°
2035-01-22 Mon	36	—	unknown	19:05–00:50 (marginal, 5.75 h)	72.5° 20:00	11.06	99%	51.2°
2035-01-23 Tue	55	—	unknown	19:05–20:05 (good, 1.0 h)	72.5° 20:00	11.03	100%	65.6°
2035-01-24 Wed	76	—	unknown	19:05–22:35 (good, 3.5 h)	72.5° 19:55	11.01	98%	79.8°
2035-01-25 Thu	100	—	unknown	19:05–00:05 (good, 5.0 h)	72.5° 19:50	10.98	94%	93.7°
2035-01-26 Fri	100	—	unknown	19:05–00:40 (good, 5.58 h)	72.5° 19:45	10.95	88%	107.2°
2035-01-27 Sat	100	—	unknown	19:10–00:45 (good, 5.58 h)	72.5° 19:40	10.92	81%	120.2°
2035-01-28 Sun	100	—	unknown	19:10–00:40 (good, 5.5 h)	72.5° 19:40	10.89	72%	132.7°
2035-01-29 Mon	100	—	unknown	19:10–00:40 (good, 5.5 h)	72.5° 19:35	10.86	63%	144.8°
2035-01-30 Tue	100	—	unknown	19:10–00:40 (good, 5.5 h)	72.5° 19:30	10.83	53%	156.2°
2035-01-31 Wed	100	—	unknown	19:15–00:35 (good, 5.33 h)	72.5° 19:25	10.8	44%	166.4°
2035-02-01 Thu	100	—	unknown	19:15–00:35 (good, 5.33 h)	72.5° 19:25	10.76	34%	170.7°
2035-02-02 Fri	100	—	unknown	19:15–00:30 (good, 5.25 h)	72.5° 19:20	10.73	26%	163.7°
2035-02-03 Sat	100	—	unknown	19:15–00:25 (good, 5.17 h)	72.5° 19:15	10.7	18%	153.1°
2035-02-04 Sun	100	—	unknown	19:15–00:20 (good, 5.08 h)	72.5° 19:10	10.66	11%	141.7°
2035-02-05 Mon	100	—	unknown	19:20–00:20 (good, 5.0 h)	72.5° 19:05	10.63	6%	129.8°
2035-02-06 Tue	100	—	unknown	19:20–00:15 (good, 4.92 h)	72.5° 19:05	10.59	2%	117.7°
2035-02-07 Wed	100	—	unknown	19:20–00:10 (good, 4.83 h)	72.5° 19:00	10.56	0%	105.3°
2035-02-08 Thu	100	—	unknown	19:20–00:05 (good, 4.75 h)	72.5° 18:55	10.52	0%	92.6°
2035-02-09 Fri	100	—	unknown	19:25–00:00 (good, 4.58 h)	72.5° 18:50	10.48	3%	79.7°
2035-02-10 Sat	100	—	unknown	19:25–00:00 (good, 4.58 h)	72.5° 18:45	10.45	7%	66.7°
2035-02-11 Sun	96	—	unknown	19:25–23:55 (good, 4.5 h)	72.5° 18:45	10.41	14%	53.4°
2035-02-12 Mon	89	—	unknown	19:25–23:50 (good, 4.42 h)	72.5° 18:40	10.37	22%	40.1°
2035-02-13 Tue	76	—	unknown	19:25–23:45 (good, 4.33 h)	72.5° 18:35	10.33	32%	26.9°
2035-02-14 Wed	58	—	unknown	19:30–23:20 (good, 3.83 h)	72.5° 18:30	10.29	43%	14.7°
2035-02-15 Thu	41	—	unknown	20:00–20:45 (good, 0.75 h)	72.5° 18:25	10.25	54%	9.6°
2035-02-16 Fri	28	—	unknown	19:30–23:50 (marginal, 4.33 h)	72.5° 18:25	10.21	66%	19.1°
2035-02-17 Sat	20	—	unknown	19:30–23:30 (marginal, 4.0 h)	72.5° 18:20	10.17	76%	32.3°
2035-02-18 Sun	21	—	unknown	19:35–23:20 (marginal, 3.75 h)	72.5° 18:15	10.13	85%	46.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-01-20&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.