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.

2035-01-26astronomy score per night — click a bar for that night2035-02-24

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2035-01-26 Fri	88	—	unknown	19:05–23:50 (good, 4.75 h)	42.9° 21:35	10.95	88%	84.8°
2035-01-27 Sat	89	—	unknown	19:10–00:25 (good, 5.25 h)	42.9° 21:30	10.92	81%	96.9°
2035-01-28 Sun	89	—	unknown	19:10–00:35 (good, 5.42 h)	42.9° 21:25	10.89	72%	108.6°
2035-01-29 Mon	89	—	unknown	19:10–00:35 (good, 5.42 h)	42.9° 21:25	10.86	63%	119.7°
2035-01-30 Tue	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.83	53%	130.3°
2035-01-31 Wed	89	—	unknown	19:15–00:35 (good, 5.33 h)	42.9° 21:15	10.8	44%	140.1°
2035-02-01 Thu	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.76	34%	148.7°
2035-02-02 Fri	89	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:05	10.73	26%	154.7°
2035-02-03 Sat	89	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:05	10.7	18%	156.4°
2035-02-04 Sun	89	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:00	10.66	11%	152.7°
2035-02-05 Mon	89	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 20:55	10.63	6%	145.1°
2035-02-06 Tue	89	—	unknown	19:20–00:10 (good, 4.83 h)	42.9° 20:50	10.59	2%	135.6°
2035-02-07 Wed	89	—	unknown	19:20–00:05 (good, 4.75 h)	42.9° 20:45	10.56	0%	124.8°
2035-02-08 Thu	89	—	unknown	19:20–00:00 (good, 4.67 h)	42.9° 20:45	10.52	0%	113.4°
2035-02-09 Fri	89	—	unknown	19:25–00:00 (good, 4.58 h)	42.9° 20:40	10.48	3%	101.6°
2035-02-10 Sat	89	—	unknown	19:25–23:55 (good, 4.5 h)	42.9° 20:35	10.45	7%	89.4°
2035-02-11 Sun	88	—	unknown	19:25–23:50 (good, 4.42 h)	42.9° 20:30	10.41	14%	77.1°
2035-02-12 Mon	84	—	unknown	19:25–23:45 (good, 4.33 h)	42.9° 20:25	10.37	22%	64.7°
2035-02-13 Tue	68	—	unknown	19:25–23:45 (good, 4.33 h)	42.9° 20:25	10.33	32%	52.5°
2035-02-14 Wed	51	—	unknown	19:30–23:15 (good, 3.75 h)	42.9° 20:20	10.29	43%	40.9°
2035-02-15 Thu	35	—	unknown	19:30–00:05 (marginal, 4.58 h)	42.9° 20:15	10.25	54%	30.7°
2035-02-16 Fri	24	—	unknown	19:30–23:45 (marginal, 4.25 h)	42.9° 20:10	10.21	66%	24.2°
2035-02-17 Sat	16	—	unknown	19:30–23:20 (marginal, 3.83 h)	42.9° 20:10	10.17	76%	24.8°
2035-02-18 Sun	12	—	unknown	19:35–22:35 (marginal, 3.0 h)	42.9° 20:05	10.13	85%	32.0°
2035-02-19 Mon	14	—	unknown	19:35–22:45 (marginal, 3.17 h)	42.9° 20:00	10.09	92%	42.7°
2035-02-20 Tue	19	—	unknown	19:35–23:00 (marginal, 3.42 h)	42.9° 19:55	10.05	97%	54.7°
2035-02-21 Wed	27	—	unknown	19:35–23:15 (marginal, 3.67 h)	42.9° 19:50	10.01	100%	67.1°
2035-02-22 Thu	37	—	unknown	19:40–20:45 (good, 1.08 h)	42.9° 19:50	9.96	100%	79.6°
2035-02-23 Fri	49	—	unknown	19:40–22:20 (good, 2.67 h)	42.9° 19:45	9.92	97%	92.0°
2035-02-24 Sat	66	—	unknown	19:40–22:40 (good, 3.0 h)	42.9° 19:40	9.88	92%	104.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2035-01-26&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.