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.

2041-01-27astronomy score per night — click a bar for that night2041-02-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2041-01-27 Sun	89	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:30	10.9	24%	147.0°
2041-01-28 Mon	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:25	10.87	15%	148.6°
2041-01-29 Tue	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.84	8%	144.6°
2041-01-30 Wed	89	—	unknown	19:10–00:35 (good, 5.42 h)	42.9° 21:15	10.81	3%	136.2°
2041-01-31 Thu	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:15	10.78	0%	125.1°
2041-02-01 Fri	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.75	1%	112.8°
2041-02-02 Sat	89	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:05	10.71	5%	100.1°
2041-02-03 Sun	89	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:00	10.68	11%	87.3°
2041-02-04 Mon	88	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 20:55	10.64	19%	75.0°
2041-02-05 Tue	84	—	unknown	19:20–00:10 (good, 4.83 h)	42.9° 20:55	10.61	29%	63.3°
2041-02-06 Wed	69	—	unknown	19:20–23:55 (good, 4.58 h)	42.9° 20:50	10.57	39%	52.6°
2041-02-07 Thu	52	—	unknown	20:00–23:35 (good, 3.58 h)	42.9° 20:45	10.54	50%	43.3°
2041-02-08 Fri	36	—	unknown	19:20–00:25 (marginal, 5.08 h)	42.9° 20:40	10.5	60%	36.0°
2041-02-09 Sat	24	—	unknown	19:25–00:10 (marginal, 4.75 h)	42.9° 20:35	10.46	69%	31.9°
2041-02-10 Sun	16	—	unknown	19:25–23:45 (marginal, 4.33 h)	42.9° 20:35	10.43	78%	31.8°
2041-02-11 Mon	14	—	unknown	19:25–23:20 (marginal, 3.92 h)	42.9° 20:30	10.39	85%	35.6°
2041-02-12 Tue	14	—	unknown	19:25–22:40 (marginal, 3.25 h)	42.9° 20:25	10.35	91%	42.2°
2041-02-13 Wed	18	—	unknown	19:30–23:10 (marginal, 3.67 h)	42.9° 20:20	10.31	96%	50.4°
2041-02-14 Thu	24	—	unknown	19:30–23:25 (marginal, 3.92 h)	42.9° 20:20	10.27	99%	59.5°
2041-02-15 Fri	32	—	unknown	19:30–23:35 (marginal, 4.08 h)	42.9° 20:15	10.23	100%	69.1°
2041-02-16 Sat	41	—	unknown	19:30–20:45 (good, 1.25 h)	42.9° 20:10	10.19	99%	79.1°
2041-02-17 Sun	52	—	unknown	19:35–22:15 (good, 2.67 h)	42.9° 20:05	10.15	97%	89.3°
2041-02-18 Mon	72	—	unknown	19:35–22:55 (good, 3.33 h)	42.9° 20:00	10.11	93%	99.5°
2041-02-19 Tue	76	—	unknown	19:35–23:05 (good, 3.5 h)	42.9° 20:00	10.07	87%	109.8°
2041-02-20 Wed	79	—	unknown	19:35–23:05 (good, 3.5 h)	42.9° 19:55	10.03	80%	119.8°
2041-02-21 Thu	78	—	unknown	19:35–23:10 (good, 3.58 h)	42.9° 19:50	9.98	71%	129.5°
2041-02-22 Fri	76	—	unknown	19:40–23:05 (good, 3.42 h)	42.9° 19:45	9.94	61%	138.3°
2041-02-23 Sat	75	—	unknown	19:40–23:00 (good, 3.33 h)	42.9° 19:40	9.9	51%	145.1°
2041-02-24 Sun	73	—	unknown	19:40–23:00 (good, 3.33 h)	42.9° 19:40	9.85	40%	148.5°
2041-02-25 Mon	72	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:35	9.81	29%	146.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2041-01-27&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.