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: 03-08 (51), 03-09 (50), 03-10 (49), 03-11 (46), 03-12 (45) — by astronomy; check the weather when the night is within four days.

2040-03-08astronomy score per night — click a bar for that night2040-04-06

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2040-03-08 Thu	51	—	unknown	19:55–22:10 (good, 2.25 h)	42.9° 18:50	9.29	22%	136.2°
2040-03-09 Fri	50	—	unknown	19:55–22:05 (good, 2.17 h)	42.9° 18:45	9.24	13%	125.4°
2040-03-10 Sat	49	—	unknown	19:55–22:00 (good, 2.08 h)	42.9° 18:40	9.19	6%	113.7°
2040-03-11 Sun	46	—	unknown	20:00–22:00 (good, 2.0 h)	42.9° 18:40	9.15	2%	101.5°
2040-03-12 Mon	45	—	unknown	20:00–21:55 (good, 1.92 h)	42.9° 18:35	9.1	0%	89.3°
2040-03-13 Tue	43	—	unknown	20:00–21:50 (good, 1.83 h)	42.9° 18:30	9.05	1%	77.3°
2040-03-14 Wed	41	—	unknown	20:00–21:45 (good, 1.75 h)	42.9° 18:25	9.0	4%	65.8°
2040-03-15 Thu	37	—	unknown	20:05–21:40 (good, 1.58 h)	42.9° 18:25	8.95	10%	55.1°
2040-03-16 Fri	32	—	unknown	20:05–21:30 (good, 1.42 h)	42.9° 18:20	8.9	16%	45.4°
2040-03-17 Sat	27	—	unknown	20:05–21:20 (good, 1.25 h)	42.9° 18:15	8.84	24%	37.3°
2040-03-18 Sun	21	—	unknown	20:05–21:05 (good, 1.0 h)	42.9° 18:10	8.79	33%	31.8°
2040-03-19 Mon	16	—	unknown	20:10–21:55 (marginal, 1.75 h)	42.9° 18:05	8.74	42%	30.0°
2040-03-20 Tue	12	—	unknown	20:10–21:45 (marginal, 1.58 h)	42.9° 18:05	8.69	52%	32.4°
2040-03-21 Wed	9	—	unknown	20:10–21:30 (marginal, 1.33 h)	42.9° 18:00	8.64	61%	38.1°
2040-03-22 Thu	8	—	unknown	20:10–21:20 (marginal, 1.17 h)	42.9° 17:55	8.59	70%	45.9°
2040-03-23 Fri	7	—	unknown	20:15–21:15 (marginal, 1.0 h)	42.9° 17:50	8.53	78%	55.0°
2040-03-24 Sat	8	—	unknown	20:15–21:15 (marginal, 1.0 h)	42.9° 17:45	8.48	86%	64.9°
2040-03-25 Sun	9	—	unknown	21:15–22:15 (marginal, 1.0 h)	42.9° 18:45	8.43	92%	75.5°
2040-03-26 Mon	10	—	unknown	21:15–22:20 (marginal, 1.08 h)	42.9° 18:40	8.37	97%	86.4°
2040-03-27 Tue	11	—	unknown	21:20–21:25 (good, 0.08 h)	42.9° 18:35	8.32	99%	97.7°
2040-03-28 Wed	12	—	unknown	21:20–21:30 (good, 0.17 h)	42.9° 18:30	8.27	100%	109.1°
2040-03-29 Thu	14	—	unknown	21:20–21:35 (good, 0.25 h)	42.9° 18:30	8.21	98%	120.4°
2040-03-30 Fri	13	—	unknown	21:25–21:45 (good, 0.33 h)	42.9° 18:25	8.16	94%	131.2°
2040-03-31 Sat	12	—	unknown	21:25–21:40 (good, 0.25 h)	42.9° 18:20	8.1	87%	140.8°
2040-04-01 Sun	10	—	unknown	21:25–21:35 (good, 0.17 h)	42.9° 18:15	8.05	79%	147.7°
2040-04-02 Mon	9	—	unknown	21:25–21:30 (good, 0.08 h)	42.9° 18:10	7.99	68%	149.8°
2040-04-03 Tue	7	—	unknown	21:30–22:00 (marginal, 0.5 h)	42.9° 18:10	7.94	57%	146.2°
2040-04-04 Wed	6	—	unknown	21:30–21:55 (marginal, 0.42 h)	42.9° 18:05	7.88	46%	138.4°
2040-04-05 Thu	5	—	unknown	21:30–21:50 (marginal, 0.33 h)	42.9° 18:00	7.83	35%	128.3°
2040-04-06 Fri	4	—	unknown	21:30–21:45 (marginal, 0.25 h)	42.9° 17:55	7.77	24%	117.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2040-03-08&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.