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: 02-13 (89), 02-14 (89), 02-15 (88), 02-16 (86), 02-17 (84) — by astronomy; check the weather when the night is within four days.

2045-02-13astronomy score per night — click a bar for that night2045-03-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2045-02-13 Mon	89	—	unknown	19:30–23:40 (good, 4.17 h)	42.9° 20:20	10.31	8%	137.2°
2045-02-14 Tue	89	—	unknown	19:30–23:35 (good, 4.08 h)	42.9° 20:20	10.27	4%	129.6°
2045-02-15 Wed	88	—	unknown	19:30–23:35 (good, 4.08 h)	42.9° 20:15	10.23	1%	120.9°
2045-02-16 Thu	86	—	unknown	19:30–23:30 (good, 4.0 h)	42.9° 20:10	10.19	0%	111.5°
2045-02-17 Fri	84	—	unknown	19:35–23:25 (good, 3.83 h)	42.9° 20:05	10.15	1%	101.7°
2045-02-18 Sat	82	—	unknown	19:35–23:20 (good, 3.75 h)	42.9° 20:00	10.11	4%	91.5°
2045-02-19 Sun	80	—	unknown	19:35–23:15 (good, 3.67 h)	42.9° 20:00	10.07	8%	81.3°
2045-02-20 Mon	74	—	unknown	19:35–23:15 (good, 3.67 h)	42.9° 19:55	10.02	14%	71.0°
2045-02-21 Tue	66	—	unknown	19:35–23:10 (good, 3.58 h)	42.9° 19:50	9.98	22%	60.8°
2045-02-22 Wed	54	—	unknown	19:40–22:50 (good, 3.17 h)	42.9° 19:45	9.94	32%	51.2°
2045-02-23 Thu	42	—	unknown	19:40–22:35 (good, 2.92 h)	42.9° 19:40	9.9	42%	42.6°
2045-02-24 Fri	30	—	unknown	19:40–23:25 (marginal, 3.75 h)	42.9° 19:40	9.85	53%	36.2°
2045-02-25 Sat	20	—	unknown	19:40–23:05 (marginal, 3.42 h)	42.9° 19:35	9.81	64%	33.6°
2045-02-26 Sun	14	—	unknown	19:45–22:45 (marginal, 3.0 h)	42.9° 19:30	9.76	74%	36.0°
2045-02-27 Mon	12	—	unknown	19:45–22:30 (marginal, 2.75 h)	42.9° 19:25	9.72	84%	42.9°
2045-02-28 Tue	14	—	unknown	19:45–22:25 (marginal, 2.67 h)	42.9° 19:25	9.67	92%	52.7°
2045-03-01 Wed	19	—	unknown	19:45–22:35 (marginal, 2.83 h)	42.9° 19:20	9.63	97%	64.0°
2045-03-02 Thu	26	—	unknown	19:50–22:45 (marginal, 2.92 h)	42.9° 19:15	9.58	100%	76.1°
2045-03-03 Fri	34	—	unknown	19:50–21:20 (good, 1.5 h)	42.9° 19:10	9.54	99%	88.4°
2045-03-04 Sat	50	—	unknown	19:50–22:00 (good, 2.17 h)	42.9° 19:05	9.49	96%	100.4°
2045-03-05 Sun	55	—	unknown	19:50–22:10 (good, 2.33 h)	42.9° 19:05	9.44	91%	112.0°
2045-03-06 Mon	56	—	unknown	19:50–22:20 (good, 2.5 h)	42.9° 19:00	9.4	84%	122.6°
2045-03-07 Tue	54	—	unknown	19:55–22:15 (good, 2.33 h)	42.9° 18:55	9.35	75%	132.1°
2045-03-08 Wed	52	—	unknown	19:55–22:10 (good, 2.25 h)	42.9° 18:50	9.3	66%	139.8°
2045-03-09 Thu	51	—	unknown	19:55–22:05 (good, 2.17 h)	42.9° 18:45	9.25	56%	144.8°
2045-03-10 Fri	49	—	unknown	19:55–22:05 (good, 2.17 h)	42.9° 18:45	9.2	46%	146.4°
2045-03-11 Sat	47	—	unknown	20:00–22:00 (good, 2.0 h)	42.9° 18:40	9.16	37%	144.3°
2045-03-12 Sun	45	—	unknown	20:00–21:55 (good, 1.92 h)	42.9° 18:35	9.11	28%	139.2°
2045-03-13 Mon	43	—	unknown	20:00–21:50 (good, 1.83 h)	42.9° 18:30	9.06	20%	132.0°
2045-03-14 Tue	42	—	unknown	20:00–21:45 (good, 1.75 h)	42.9° 18:30	9.01	13%	123.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2045-02-13&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.