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: 10-23 (89), 10-24 (89), 10-25 (89), 10-26 (89), 10-27 (89) — by astronomy; check the weather when the night is within four days.

2030-09-30astronomy score per night — click a bar for that night2030-10-29

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-09-30 Mon	62	—	unknown	03:05–05:50 (good, 2.75 h)	42.9° 06:20	9.13	16%	139.7°
2030-10-01 Tue	63	—	unknown	03:00–05:50 (good, 2.83 h)	42.9° 06:15	9.18	25%	148.5°
2030-10-02 Wed	65	—	unknown	02:55–05:50 (good, 2.92 h)	42.9° 06:10	9.23	36%	152.6°
2030-10-03 Thu	67	—	unknown	02:50–05:50 (good, 3.0 h)	42.9° 06:05	9.28	47%	150.3°
2030-10-04 Fri	69	—	unknown	02:50–05:50 (good, 3.0 h)	42.9° 06:00	9.32	58%	142.9°
2030-10-05 Sat	70	—	unknown	02:45–05:55 (good, 3.17 h)	42.9° 06:00	9.37	69%	133.0°
2030-10-06 Sun	71	—	unknown	02:45–05:55 (good, 3.17 h)	42.9° 05:55	9.42	79%	121.9°
2030-10-07 Mon	70	—	unknown	02:50–05:55 (good, 3.08 h)	42.9° 05:50	9.46	87%	110.4°
2030-10-08 Tue	65	—	unknown	03:00–05:55 (good, 2.92 h)	42.9° 05:45	9.51	93%	98.8°
2030-10-09 Wed	46	—	unknown	03:40–06:00 (good, 2.33 h)	42.9° 05:45	9.56	97%	87.3°
2030-10-10 Thu	35	—	unknown	05:20–06:00 (good, 0.67 h)	42.9° 05:40	9.6	100%	76.0°
2030-10-11 Fri	26	—	unknown	02:20–06:00 (marginal, 3.67 h)	42.9° 05:35	9.65	100%	65.0°
2030-10-12 Sat	19	—	unknown	02:35–06:00 (marginal, 3.42 h)	42.9° 05:30	9.69	98%	54.6°
2030-10-13 Sun	14	—	unknown	02:50–06:00 (marginal, 3.17 h)	42.9° 05:25	9.74	94%	44.9°
2030-10-14 Mon	12	—	unknown	03:50–06:05 (marginal, 2.25 h)	42.9° 05:25	9.78	89%	36.4°
2030-10-15 Tue	12	—	unknown	02:30–06:05 (marginal, 3.58 h)	42.9° 05:20	9.82	82%	30.0°
2030-10-16 Wed	17	—	unknown	02:00–06:05 (marginal, 4.08 h)	42.9° 05:15	9.87	75%	27.3°
2030-10-17 Thu	24	—	unknown	01:40–06:05 (marginal, 4.42 h)	42.9° 05:10	9.91	66%	29.0°
2030-10-18 Fri	36	—	unknown	01:25–06:05 (marginal, 4.67 h)	42.9° 05:05	9.95	57%	34.7°
2030-10-19 Sat	50	—	unknown	02:15–06:10 (good, 3.92 h)	42.9° 05:05	9.99	47%	42.8°
2030-10-20 Sun	65	—	unknown	02:00–06:10 (good, 4.17 h)	42.9° 05:00	10.03	37%	52.5°
2030-10-21 Mon	82	—	unknown	01:40–06:10 (good, 4.5 h)	42.9° 04:55	10.08	28%	63.1°
2030-10-22 Tue	87	—	unknown	01:40–06:10 (good, 4.5 h)	42.9° 04:50	10.12	19%	74.4°
2030-10-23 Wed	89	—	unknown	01:35–06:15 (good, 4.67 h)	42.9° 04:50	10.16	11%	86.3°
2030-10-24 Thu	89	—	unknown	01:30–06:15 (good, 4.75 h)	42.9° 04:45	10.2	5%	98.7°
2030-10-25 Fri	89	—	unknown	01:25–06:15 (good, 4.83 h)	42.9° 04:40	10.24	1%	111.3°
2030-10-26 Sat	89	—	unknown	01:20–05:15 (good, 4.92 h)	42.9° 03:35	10.28	0%	123.9°
2030-10-27 Sun	89	—	unknown	00:20–05:15 (good, 4.92 h)	42.9° 03:30	10.32	2%	135.8°
2030-10-28 Mon	89	—	unknown	00:15–05:20 (good, 5.08 h)	42.9° 03:30	10.35	6%	145.9°
2030-10-29 Tue	89	—	unknown	00:10–05:20 (good, 5.17 h)	42.9° 03:25	10.39	13%	152.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-09-30&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.