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: 10-17 (89), 10-18 (89), 10-19 (89), 10-20 (89), 10-21 (89) — by astronomy; check the weather when the night is within four days.

2042-09-28astronomy score per night — click a bar for that night2042-10-27

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-09-28 Sun	31	—	unknown	04:40–05:45 (good, 1.08 h)	42.9° 06:25	9.04	100%	84.2°
2042-09-29 Mon	23	—	unknown	03:00–05:45 (marginal, 2.75 h)	42.9° 06:20	9.09	100%	71.7°
2042-09-30 Tue	16	—	unknown	03:10–05:50 (marginal, 2.67 h)	42.9° 06:20	9.14	97%	59.6°
2042-10-01 Wed	12	—	unknown	03:20–05:50 (marginal, 2.5 h)	42.9° 06:15	9.19	91%	48.6°
2042-10-02 Thu	11	—	unknown	03:15–05:50 (marginal, 2.58 h)	42.9° 06:10	9.23	83%	39.7°
2042-10-03 Fri	14	—	unknown	02:55–05:50 (marginal, 2.92 h)	42.9° 06:05	9.28	73%	34.4°
2042-10-04 Sat	19	—	unknown	02:35–05:50 (marginal, 3.25 h)	42.9° 06:05	9.33	63%	33.8°
2042-10-05 Sun	29	—	unknown	02:15–05:55 (marginal, 3.67 h)	42.9° 06:00	9.38	52%	37.9°
2042-10-06 Mon	41	—	unknown	03:05–05:55 (good, 2.83 h)	42.9° 05:55	9.42	41%	45.0°
2042-10-07 Tue	53	—	unknown	02:50–05:55 (good, 3.08 h)	42.9° 05:50	9.47	32%	53.7°
2042-10-08 Wed	63	—	unknown	02:35–05:55 (good, 3.33 h)	42.9° 05:45	9.51	23%	63.2°
2042-10-09 Thu	71	—	unknown	02:30–06:00 (good, 3.5 h)	42.9° 05:45	9.56	15%	73.0°
2042-10-10 Fri	77	—	unknown	02:25–06:00 (good, 3.58 h)	42.9° 05:40	9.61	9%	83.0°
2042-10-11 Sat	80	—	unknown	02:20–06:00 (good, 3.67 h)	42.9° 05:35	9.65	4%	93.0°
2042-10-12 Sun	82	—	unknown	02:15–06:00 (good, 3.75 h)	42.9° 05:30	9.69	1%	102.9°
2042-10-13 Mon	83	—	unknown	02:15–06:00 (good, 3.75 h)	42.9° 05:25	9.74	0%	112.5°
2042-10-14 Tue	85	—	unknown	02:10–06:05 (good, 3.92 h)	42.9° 05:25	9.78	1%	121.8°
2042-10-15 Wed	86	—	unknown	02:05–06:05 (good, 4.0 h)	42.9° 05:20	9.83	3%	130.4°
2042-10-16 Thu	88	—	unknown	02:00–06:05 (good, 4.08 h)	42.9° 05:15	9.87	7%	138.0°
2042-10-17 Fri	89	—	unknown	01:55–06:05 (good, 4.17 h)	42.9° 05:10	9.91	13%	143.6°
2042-10-18 Sat	89	—	unknown	01:55–06:05 (good, 4.17 h)	42.9° 05:10	9.95	20%	146.4°
2042-10-19 Sun	89	—	unknown	01:50–06:10 (good, 4.33 h)	42.9° 05:05	10.0	28%	145.5°
2042-10-20 Mon	89	—	unknown	01:45–06:10 (good, 4.42 h)	42.9° 05:00	10.04	38%	140.8°
2042-10-21 Tue	89	—	unknown	01:40–06:10 (good, 4.5 h)	42.9° 04:55	10.08	48%	133.4°
2042-10-22 Wed	89	—	unknown	01:40–06:10 (good, 4.5 h)	42.9° 04:50	10.12	58%	124.1°
2042-10-23 Thu	89	—	unknown	01:40–06:15 (good, 4.58 h)	42.9° 04:50	10.16	69%	113.5°
2042-10-24 Fri	89	—	unknown	01:45–06:15 (good, 4.5 h)	42.9° 04:45	10.2	79%	102.1°
2042-10-25 Sat	89	—	unknown	01:55–05:15 (good, 4.33 h)	42.9° 03:40	10.24	88%	90.0°
2042-10-26 Sun	76	—	unknown	02:25–05:15 (good, 2.83 h)	42.9° 03:35	10.28	94%	77.6°
2042-10-27 Mon	41	—	unknown	00:15–05:15 (marginal, 5.0 h)	42.9° 03:30	10.32	99%	65.2°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-09-28&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.