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: 10-07 (74), 10-08 (74), 10-06 (72), 10-05 (70), 10-04 (68) — by astronomy; check the weather when the night is within four days.

2043-09-09astronomy score per night — click a bar for that night2043-10-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-09-09 Wed	25	—	unknown	04:30–05:20 (good, 0.83 h)	42.9° 07:40	8.05	35%	139.8°
2043-09-10 Thu	27	—	unknown	04:25–05:25 (good, 1.0 h)	42.9° 07:40	8.1	44%	144.5°
2043-09-11 Fri	29	—	unknown	04:20–05:25 (good, 1.08 h)	42.9° 07:35	8.15	54%	146.1°
2043-09-12 Sat	30	—	unknown	04:15–05:25 (good, 1.17 h)	42.9° 07:30	8.21	63%	144.0°
2043-09-13 Sun	32	—	unknown	04:10–05:25 (good, 1.25 h)	42.9° 07:25	8.26	72%	138.8°
2043-09-14 Mon	34	—	unknown	04:10–05:30 (good, 1.33 h)	42.9° 07:20	8.31	81%	131.2°
2043-09-15 Tue	35	—	unknown	04:05–05:30 (good, 1.42 h)	42.9° 07:20	8.37	88%	121.9°
2043-09-16 Wed	35	—	unknown	04:15–05:30 (good, 1.25 h)	42.9° 07:15	8.42	94%	111.6°
2043-09-17 Thu	27	—	unknown	04:20–05:30 (good, 1.17 h)	42.9° 07:10	8.47	98%	100.5°
2043-09-18 Fri	22	—	unknown	04:50–05:35 (good, 0.75 h)	42.9° 07:05	8.52	100%	88.9°
2043-09-19 Sat	17	—	unknown	03:35–05:35 (marginal, 2.0 h)	42.9° 07:05	8.57	99%	77.1°
2043-09-20 Sun	13	—	unknown	03:40–05:35 (marginal, 1.92 h)	42.9° 07:00	8.63	95%	65.4°
2043-09-21 Mon	11	—	unknown	03:50–05:35 (marginal, 1.75 h)	42.9° 06:55	8.68	89%	54.3°
2043-09-22 Tue	10	—	unknown	03:45–05:40 (marginal, 1.92 h)	42.9° 06:50	8.73	81%	44.5°
2043-09-23 Wed	12	—	unknown	03:30–05:40 (marginal, 2.17 h)	42.9° 06:45	8.78	71%	37.2°
2043-09-24 Thu	16	—	unknown	03:15–05:40 (marginal, 2.42 h)	42.9° 06:45	8.83	60%	34.0°
2043-09-25 Fri	23	—	unknown	02:55–05:40 (marginal, 2.75 h)	42.9° 06:40	8.88	48%	35.7°
2043-09-26 Sat	33	—	unknown	03:45–05:45 (good, 2.0 h)	42.9° 06:35	8.93	37%	41.7°
2043-09-27 Sun	42	—	unknown	03:30–05:45 (good, 2.25 h)	42.9° 06:30	8.98	27%	50.2°
2043-09-28 Mon	51	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:25	9.03	18%	60.0°
2043-09-29 Tue	56	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:25	9.08	10%	70.5°
2043-09-30 Wed	60	—	unknown	03:05–05:45 (good, 2.67 h)	42.9° 06:20	9.13	5%	81.1°
2043-10-01 Thu	63	—	unknown	03:00–05:50 (good, 2.83 h)	42.9° 06:15	9.17	2%	91.7°
2043-10-02 Fri	65	—	unknown	02:55–05:50 (good, 2.92 h)	42.9° 06:10	9.22	0%	102.1°
2043-10-03 Sat	67	—	unknown	02:55–05:50 (good, 2.92 h)	42.9° 06:10	9.27	1%	112.2°
2043-10-04 Sun	68	—	unknown	02:50–05:50 (good, 3.0 h)	42.9° 06:05	9.32	3%	121.7°
2043-10-05 Mon	70	—	unknown	02:45–05:55 (good, 3.17 h)	42.9° 06:00	9.36	7%	130.4°
2043-10-06 Tue	72	—	unknown	02:40–05:55 (good, 3.25 h)	42.9° 05:55	9.41	13%	137.8°
2043-10-07 Wed	74	—	unknown	02:40–05:55 (good, 3.25 h)	42.9° 05:50	9.46	20%	143.3°
2043-10-08 Thu	74	—	unknown	02:35–05:55 (good, 3.33 h)	42.9° 05:50	9.5	28%	146.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-09-09&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.