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: 01-26 (89), 01-27 (89), 01-28 (89), 01-29 (89), 01-30 (89) — by astronomy; check the weather when the night is within four days.

2038-01-26astronomy score per night — click a bar for that night2038-02-24

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-01-26 Tue	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:35	10.94	61%	119.8°
2038-01-27 Wed	89	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:30	10.91	50%	131.6°
2038-01-28 Thu	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:25	10.88	39%	142.1°
2038-01-29 Fri	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.85	28%	150.2°
2038-01-30 Sat	89	—	unknown	19:10–00:35 (good, 5.42 h)	42.9° 21:20	10.82	19%	153.8°
2038-01-31 Sun	89	—	unknown	19:15–00:35 (good, 5.33 h)	42.9° 21:15	10.79	11%	151.2°
2038-02-01 Mon	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.75	6%	144.1°
2038-02-02 Tue	89	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:05	10.72	2%	134.7°
2038-02-03 Wed	89	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:00	10.69	0%	124.2°
2038-02-04 Thu	89	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 21:00	10.65	0%	113.4°
2038-02-05 Fri	89	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 20:55	10.62	3%	102.5°
2038-02-06 Sat	89	—	unknown	19:20–00:10 (good, 4.83 h)	42.9° 20:50	10.58	7%	91.6°
2038-02-07 Sun	89	—	unknown	19:20–00:05 (good, 4.75 h)	42.9° 20:45	10.55	13%	80.9°
2038-02-08 Mon	87	—	unknown	19:20–00:00 (good, 4.67 h)	42.9° 20:40	10.51	20%	70.4°
2038-02-09 Tue	83	—	unknown	19:25–00:00 (good, 4.58 h)	42.9° 20:40	10.47	28%	60.1°
2038-02-10 Wed	67	—	unknown	19:25–23:40 (good, 4.25 h)	42.9° 20:35	10.44	36%	50.1°
2038-02-11 Thu	52	—	unknown	19:25–23:25 (good, 4.0 h)	42.9° 20:30	10.4	46%	40.8°
2038-02-12 Fri	37	—	unknown	19:25–00:15 (marginal, 4.83 h)	42.9° 20:25	10.36	55%	32.8°
2038-02-13 Sat	26	—	unknown	19:30–00:00 (marginal, 4.5 h)	42.9° 20:25	10.32	65%	27.4°
2038-02-14 Sun	17	—	unknown	19:30–23:35 (marginal, 4.08 h)	42.9° 20:20	10.28	74%	26.7°
2038-02-15 Mon	13	—	unknown	19:30–23:05 (marginal, 3.58 h)	42.9° 20:15	10.24	83%	31.4°
2038-02-16 Tue	13	—	unknown	19:30–22:25 (marginal, 2.92 h)	42.9° 20:10	10.2	90%	40.1°
2038-02-17 Wed	17	—	unknown	19:30–23:00 (marginal, 3.5 h)	42.9° 20:05	10.16	96%	51.1°
2038-02-18 Thu	25	—	unknown	19:35–23:15 (marginal, 3.67 h)	42.9° 20:05	10.12	99%	63.3°
2038-02-19 Fri	36	—	unknown	19:35–20:00 (good, 0.42 h)	42.9° 20:00	10.08	100%	76.2°
2038-02-20 Sat	48	—	unknown	19:35–22:05 (good, 2.5 h)	42.9° 19:55	10.04	98%	89.5°
2038-02-21 Sun	69	—	unknown	19:35–22:50 (good, 3.25 h)	42.9° 19:50	10.0	92%	102.9°
2038-02-22 Mon	73	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:45	9.95	85%	116.0°
2038-02-23 Tue	75	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:45	9.91	76%	128.4°
2038-02-24 Wed	73	—	unknown	19:40–23:00 (good, 3.33 h)	42.9° 19:40	9.87	65%	139.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-01-26&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.