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: 03-29 (16), 03-30 (13), 03-31 (11), 04-01 (9), 04-02 (6) — by astronomy; check the weather when the night is within four days.

2044-03-29astronomy score per night — click a bar for that night2044-04-27

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2044-03-29 Tue	16	—	unknown	21:20–21:45 (good, 0.42 h)	42.9° 18:30	8.21	0%	70.4°
2044-03-30 Wed	13	—	unknown	21:25–21:45 (good, 0.33 h)	42.9° 18:25	8.16	3%	59.3°
2044-03-31 Thu	11	—	unknown	21:25–21:35 (good, 0.17 h)	42.9° 18:20	8.1	8%	48.9°
2044-04-01 Fri	9	—	unknown	20:50–22:05 (marginal, 1.25 h)	42.9° 18:15	8.05	16%	40.3°
2044-04-02 Sat	6	—	unknown	21:25–22:00 (marginal, 0.58 h)	42.9° 18:10	7.99	25%	34.9°
2044-04-03 Sun	4	—	unknown	21:30–22:00 (marginal, 0.5 h)	42.9° 18:10	7.94	36%	34.3°
2044-04-04 Mon	3	—	unknown	21:30–21:50 (marginal, 0.33 h)	42.9° 18:05	7.88	47%	38.6°
2044-04-05 Tue	2	—	unknown	21:30–21:35 (marginal, 0.08 h)	42.9° 18:00	7.83	59%	46.3°
2044-04-06 Wed	1	—	unknown	—	42.9° 17:55	7.77	70%	55.9°
2044-04-07 Thu	1	—	unknown	—	42.9° 17:50	7.71	79%	66.4°
2044-04-08 Fri	1	—	unknown	—	42.9° 17:50	7.66	87%	77.4°
2044-04-09 Sat	1	—	unknown	—	42.9° 17:45	7.6	94%	88.4°
2044-04-10 Sun	1	—	unknown	—	42.9° 17:40	7.54	98%	99.3°
2044-04-11 Mon	1	—	unknown	—	42.9° 17:35	7.49	100%	109.8°
2044-04-12 Tue	1	—	unknown	—	42.9° 17:35	7.43	100%	119.8°
2044-04-13 Wed	1	—	unknown	—	42.9° 17:30	7.37	98%	129.0°
2044-04-14 Thu	0	—	unknown	—	42.9° 17:25	7.31	94%	136.9°
2044-04-15 Fri	0	—	unknown	—	42.9° 17:20	7.26	88%	142.8°
2044-04-16 Sat	0	—	unknown	—	42.9° 17:15	7.2	81%	145.9°
2044-04-17 Sun	0	—	unknown	—	42.9° 17:15	7.14	73%	145.5°
2044-04-18 Mon	0	—	unknown	—	42.9° 17:10	7.08	65%	141.7°
2044-04-19 Tue	0	—	unknown	—	42.9° 17:05	7.02	55%	135.4°
2044-04-20 Wed	0	—	unknown	—	42.9° 17:00	6.97	46%	127.4°
2044-04-21 Thu	0	—	unknown	—	42.9° 16:55	6.91	36%	118.2°
2044-04-22 Fri	0	—	unknown	—	42.9° 16:55	6.85	27%	108.2°
2044-04-23 Sat	0	—	unknown	—	42.9° 16:50	6.79	18%	97.6°
2044-04-24 Sun	0	—	unknown	—	42.9° 16:45	6.73	11%	86.5°
2044-04-25 Mon	0	—	unknown	—	42.9° 16:40	6.67	5%	75.1°
2044-04-26 Tue	0	—	unknown	—	42.9° 16:40	6.62	1%	63.7°
2044-04-27 Wed	0	—	unknown	—	42.9° 16:35	6.56	0%	52.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-03-29&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.