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 Great Orion Nebula: 01-27 (89), 01-28 (89), 01-29 (89), 01-30 (89), 01-31 (89) — by astronomy; check the weather when the night is within four days.

2036-01-27astronomy score per night — click a bar for that night2036-02-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2036-01-27 Sun	89	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:30	10.93	0%	134.2°
2036-01-28 Mon	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:25	10.9	0%	124.0°
2036-01-29 Tue	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:25	10.87	2%	113.4°
2036-01-30 Wed	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.84	6%	102.5°
2036-01-31 Thu	89	—	unknown	19:15–00:35 (good, 5.33 h)	42.9° 21:15	10.8	11%	91.4°
2036-02-01 Fri	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.77	18%	80.0°
2036-02-02 Sat	86	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:10	10.74	26%	68.6°
2036-02-03 Sun	81	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:05	10.7	36%	57.2°
2036-02-04 Mon	62	—	unknown	19:15–00:00 (good, 4.75 h)	42.9° 21:00	10.67	46%	46.0°
2036-02-05 Tue	43	—	unknown	19:20–00:45 (marginal, 5.42 h)	42.9° 20:55	10.64	57%	35.4°
2036-02-06 Wed	28	—	unknown	19:20–00:30 (marginal, 5.17 h)	42.9° 20:50	10.6	68%	27.1°
2036-02-07 Thu	18	—	unknown	19:20–00:05 (marginal, 4.75 h)	42.9° 20:50	10.57	78%	24.0°
2036-02-08 Fri	13	—	unknown	19:20–20:30 (marginal, 1.17 h)	42.9° 20:45	10.53	87%	28.5°
2036-02-09 Sat	14	—	unknown	19:25–21:30 (marginal, 2.08 h)	42.9° 20:40	10.49	94%	38.4°
2036-02-10 Sun	21	—	unknown	19:25–23:25 (marginal, 4.0 h)	42.9° 20:35	10.46	98%	50.7°
2036-02-11 Mon	32	—	unknown	19:25–23:45 (marginal, 4.33 h)	42.9° 20:30	10.42	100%	63.9°
2036-02-12 Tue	46	—	unknown	19:25–21:00 (good, 1.58 h)	42.9° 20:30	10.38	98%	77.4°
2036-02-13 Wed	75	—	unknown	19:25–22:55 (good, 3.5 h)	42.9° 20:25	10.34	94%	90.7°
2036-02-14 Thu	83	—	unknown	19:30–23:20 (good, 3.83 h)	42.9° 20:20	10.3	88%	103.7°
2036-02-15 Fri	86	—	unknown	19:30–23:25 (good, 3.92 h)	42.9° 20:15	10.26	80%	116.1°
2036-02-16 Sat	87	—	unknown	19:30–23:25 (good, 3.92 h)	42.9° 20:15	10.22	70%	127.8°
2036-02-17 Sun	86	—	unknown	19:30–23:30 (good, 4.0 h)	42.9° 20:10	10.18	60%	138.5°
2036-02-18 Mon	84	—	unknown	19:35–23:25 (good, 3.83 h)	42.9° 20:05	10.14	50%	147.6°
2036-02-19 Tue	82	—	unknown	19:35–23:20 (good, 3.75 h)	42.9° 20:00	10.1	41%	154.0°
2036-02-20 Wed	80	—	unknown	19:35–23:15 (good, 3.67 h)	42.9° 19:55	10.06	32%	156.0°
2036-02-21 Thu	80	—	unknown	19:35–23:10 (good, 3.58 h)	42.9° 19:55	10.02	23%	152.7°
2036-02-22 Fri	78	—	unknown	19:35–23:10 (good, 3.58 h)	42.9° 19:50	9.97	16%	145.7°
2036-02-23 Sat	76	—	unknown	19:40–23:05 (good, 3.42 h)	42.9° 19:45	9.93	10%	136.8°
2036-02-24 Sun	74	—	unknown	19:40–23:00 (good, 3.33 h)	42.9° 19:40	9.89	5%	126.9°
2036-02-25 Mon	73	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:35	9.84	2%	116.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2036-01-27&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.