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: 02-17 (85), 02-18 (83), 02-19 (82), 02-20 (80), 02-21 (78) — by astronomy; check the weather when the night is within four days.

2042-02-17astronomy score per night — click a bar for that night2042-03-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-02-17 Mon	85	—	unknown	19:30–23:25 (good, 3.92 h)	42.9° 20:05	10.16	8%	133.3°
2042-02-18 Tue	83	—	unknown	19:35–23:20 (good, 3.75 h)	42.9° 20:05	10.12	3%	122.8°
2042-02-19 Wed	82	—	unknown	19:35–23:20 (good, 3.75 h)	42.9° 20:00	10.08	0%	111.0°
2042-02-20 Thu	80	—	unknown	19:35–23:15 (good, 3.67 h)	42.9° 19:55	10.04	1%	98.5°
2042-02-21 Fri	78	—	unknown	19:35–23:10 (good, 3.58 h)	42.9° 19:50	9.99	4%	85.7°
2042-02-22 Sat	74	—	unknown	19:40–23:05 (good, 3.42 h)	42.9° 19:45	9.95	10%	73.2°
2042-02-23 Sun	66	—	unknown	19:40–23:05 (good, 3.42 h)	42.9° 19:45	9.91	18%	61.3°
2042-02-24 Mon	55	—	unknown	19:40–22:50 (good, 3.17 h)	42.9° 19:40	9.86	28%	50.4°
2042-02-25 Tue	42	—	unknown	19:40–22:30 (good, 2.83 h)	42.9° 19:35	9.82	39%	41.3°
2042-02-26 Wed	30	—	unknown	19:45–23:20 (marginal, 3.58 h)	42.9° 19:30	9.78	50%	35.1°
2042-02-27 Thu	21	—	unknown	19:45–23:05 (marginal, 3.33 h)	42.9° 19:30	9.73	60%	32.8°
2042-02-28 Fri	15	—	unknown	19:45–22:45 (marginal, 3.0 h)	42.9° 19:25	9.69	70%	35.0°
2042-03-01 Sat	13	—	unknown	19:45–22:30 (marginal, 2.75 h)	42.9° 19:20	9.64	79%	40.7°
2042-03-02 Sun	13	—	unknown	19:45–22:20 (marginal, 2.58 h)	42.9° 19:15	9.6	86%	48.6°
2042-03-03 Mon	15	—	unknown	19:50–22:20 (marginal, 2.5 h)	42.9° 19:10	9.55	92%	57.5°
2042-03-04 Tue	19	—	unknown	19:50–22:30 (marginal, 2.67 h)	42.9° 19:10	9.5	97%	67.1°
2042-03-05 Wed	23	—	unknown	19:50–22:35 (marginal, 2.75 h)	42.9° 19:05	9.46	99%	76.9°
2042-03-06 Thu	29	—	unknown	19:50–20:45 (good, 0.92 h)	42.9° 19:00	9.41	100%	86.8°
2042-03-07 Fri	34	—	unknown	19:55–21:45 (good, 1.83 h)	42.9° 18:55	9.36	99%	96.8°
2042-03-08 Sat	46	—	unknown	19:55–21:50 (good, 1.92 h)	42.9° 18:50	9.31	96%	106.6°
2042-03-09 Sun	49	—	unknown	19:55–21:55 (good, 2.0 h)	42.9° 18:50	9.27	92%	116.2°
2042-03-10 Mon	49	—	unknown	19:55–22:05 (good, 2.17 h)	42.9° 18:45	9.22	86%	125.4°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-02-17&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.