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: 03-11 (47), 03-12 (45), 03-13 (44), 03-14 (42), 03-15 (40) — by astronomy; check the weather when the night is within four days.

2042-03-11astronomy score per night — click a bar for that night2042-04-09

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-03-11 Tue	47	—	unknown	20:00–22:00 (good, 2.0 h)	42.9° 18:40	9.17	78%	133.9°
2042-03-12 Wed	45	—	unknown	20:00–21:55 (good, 1.92 h)	42.9° 18:35	9.12	70%	141.0°
2042-03-13 Thu	44	—	unknown	20:00–21:50 (good, 1.83 h)	42.9° 18:35	9.07	60%	145.8°
2042-03-14 Fri	42	—	unknown	20:00–21:50 (good, 1.83 h)	42.9° 18:30	9.02	50%	147.0°
2042-03-15 Sat	40	—	unknown	20:05–21:45 (good, 1.67 h)	42.9° 18:25	8.97	40%	143.8°
2042-03-16 Sun	38	—	unknown	20:05–21:40 (good, 1.58 h)	42.9° 18:20	8.92	30%	136.9°
2042-03-17 Mon	37	—	unknown	20:05–21:35 (good, 1.5 h)	42.9° 18:15	8.87	20%	127.5°
2042-03-18 Tue	36	—	unknown	20:05–21:30 (good, 1.42 h)	42.9° 18:15	8.82	11%	116.5°
2042-03-19 Wed	33	—	unknown	20:10–21:30 (good, 1.33 h)	42.9° 18:10	8.77	5%	104.4°
2042-03-20 Thu	32	—	unknown	20:10–21:25 (good, 1.25 h)	42.9° 18:05	8.72	1%	91.8°
2042-03-21 Fri	30	—	unknown	20:10–21:20 (good, 1.17 h)	42.9° 18:00	8.66	0%	79.0°
2042-03-22 Sat	28	—	unknown	20:10–21:15 (good, 1.08 h)	42.9° 17:55	8.61	2%	66.5°
2042-03-23 Sun	26	—	unknown	20:15–21:10 (good, 0.92 h)	42.9° 17:55	8.56	7%	54.8°
2042-03-24 Mon	22	—	unknown	20:15–21:00 (good, 0.75 h)	42.9° 17:50	8.51	15%	44.6°
2042-03-25 Tue	18	—	unknown	20:15–20:50 (good, 0.58 h)	42.9° 17:45	8.45	24%	36.9°
2042-03-26 Wed	13	—	unknown	20:15–20:30 (good, 0.25 h)	42.9° 17:40	8.4	34%	33.2°
2042-03-27 Thu	10	—	unknown	20:20–21:25 (marginal, 1.08 h)	42.9° 17:40	8.35	44%	34.2°
2042-03-28 Fri	7	—	unknown	20:20–21:10 (marginal, 0.83 h)	42.9° 17:35	8.29	55%	39.1°
2042-03-29 Sat	6	—	unknown	20:20–21:00 (marginal, 0.67 h)	42.9° 17:30	8.24	64%	46.6°
2042-03-30 Sun	5	—	unknown	21:20–21:55 (marginal, 0.58 h)	42.9° 18:25	8.18	74%	55.3°
2042-03-31 Mon	4	—	unknown	21:25–21:50 (marginal, 0.42 h)	42.9° 18:20	8.13	82%	64.7°
2042-04-01 Tue	4	—	unknown	21:25–21:55 (marginal, 0.5 h)	42.9° 18:20	8.08	88%	74.4°
2042-04-02 Wed	4	—	unknown	21:25–21:55 (marginal, 0.5 h)	42.9° 18:15	8.02	94%	84.3°
2042-04-03 Thu	5	—	unknown	21:25–22:00 (marginal, 0.58 h)	42.9° 18:10	7.97	98%	94.2°
2042-04-04 Fri	4	—	unknown	21:30–21:55 (marginal, 0.42 h)	42.9° 18:05	7.91	100%	104.1°
2042-04-05 Sat	4	—	unknown	21:30–21:50 (marginal, 0.33 h)	42.9° 18:00	7.85	100%	113.8°
2042-04-06 Sun	4	—	unknown	21:30–21:50 (marginal, 0.33 h)	42.9° 18:00	7.8	98%	123.1°
2042-04-07 Mon	3	—	unknown	21:00–21:15 (marginal, 0.25 h)	42.9° 17:55	7.74	95%	131.8°
2042-04-08 Tue	3	—	unknown	21:00–21:10 (marginal, 0.17 h)	42.9° 17:50	7.69	90%	139.3°
2042-04-09 Wed	2	—	unknown	21:00–21:05 (marginal, 0.08 h)	42.9° 17:45	7.63	83%	144.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-03-11&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.