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: 01-23 (89), 01-24 (89), 01-25 (89), 02-08 (89), 02-09 (89) — by astronomy; check the weather when the night is within four days.

2042-01-23astronomy score per night — click a bar for that night2042-02-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-01-23 Thu	89	—	unknown	19:05–01:05 (good, 6.0 h)	42.9° 21:45	11.03	6%	105.6°
2042-01-24 Fri	89	—	unknown	19:05–01:00 (good, 5.92 h)	42.9° 21:40	11.0	13%	93.2°
2042-01-25 Sat	89	—	unknown	19:05–00:55 (good, 5.83 h)	42.9° 21:35	10.97	22%	80.9°
2042-01-26 Sun	85	—	unknown	19:10–00:55 (good, 5.75 h)	42.9° 21:35	10.94	32%	68.9°
2042-01-27 Mon	73	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:30	10.91	43%	57.7°
2042-01-28 Tue	58	—	unknown	21:00–00:15 (good, 3.25 h)	42.9° 21:25	10.88	55%	47.6°
2042-01-29 Wed	39	—	unknown	19:10–01:05 (marginal, 5.92 h)	42.9° 21:20	10.85	65%	39.3°
2042-01-30 Thu	25	—	unknown	19:10–00:45 (marginal, 5.58 h)	42.9° 21:20	10.82	75%	33.9°
2042-01-31 Fri	16	—	unknown	19:15–00:15 (marginal, 5.0 h)	42.9° 21:15	10.79	83%	32.7°
2042-02-01 Sat	14	—	unknown	19:15–20:40 (marginal, 1.42 h)	42.9° 21:10	10.75	90%	35.9°
2042-02-02 Sun	16	—	unknown	19:15–21:50 (marginal, 2.58 h)	42.9° 21:05	10.72	95%	42.3°
2042-02-03 Mon	21	—	unknown	19:15–23:40 (marginal, 4.42 h)	42.9° 21:00	10.69	98%	50.6°
2042-02-04 Tue	30	—	unknown	19:20–00:05 (marginal, 4.75 h)	42.9° 21:00	10.65	100%	59.9°
2042-02-05 Wed	41	—	unknown	19:20–00:15 (marginal, 4.92 h)	42.9° 20:55	10.62	99%	69.6°
2042-02-06 Thu	54	—	unknown	19:20–21:45 (good, 2.42 h)	42.9° 20:50	10.58	97%	79.6°
2042-02-07 Fri	82	—	unknown	19:20–23:15 (good, 3.92 h)	42.9° 20:45	10.55	93%	89.6°
2042-02-08 Sat	89	—	unknown	19:20–23:40 (good, 4.33 h)	42.9° 20:40	10.51	87%	99.5°
2042-02-09 Sun	89	—	unknown	19:25–23:45 (good, 4.33 h)	42.9° 20:40	10.47	80%	109.3°
2042-02-10 Mon	89	—	unknown	19:25–23:45 (good, 4.33 h)	42.9° 20:35	10.44	72%	118.9°
2042-02-11 Tue	89	—	unknown	19:25–23:50 (good, 4.42 h)	42.9° 20:30	10.4	63%	128.0°
2042-02-12 Wed	89	—	unknown	19:25–23:45 (good, 4.33 h)	42.9° 20:25	10.36	54%	136.2°
2042-02-13 Thu	89	—	unknown	19:30–23:40 (good, 4.17 h)	42.9° 20:25	10.32	44%	143.0°
2042-02-14 Fri	89	—	unknown	19:30–23:40 (good, 4.17 h)	42.9° 20:20	10.28	34%	146.8°
2042-02-15 Sat	88	—	unknown	19:30–23:35 (good, 4.08 h)	42.9° 20:15	10.24	24%	146.5°
2042-02-16 Sun	87	—	unknown	19:30–23:30 (good, 4.0 h)	42.9° 20:10	10.2	15%	141.6°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-01-23&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.