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: 10-28 (89), 10-29 (89), 10-30 (89), 10-31 (89), 11-01 (89) — by astronomy; check the weather when the night is within four days.

2027-10-28astronomy score per night — click a bar for that night2027-11-26

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-10-28 Thu	89	—	unknown	01:15–06:20 (good, 5.08 h)	42.9° 04:30	10.34	1%	116.5°
2027-10-29 Fri	89	—	unknown	01:10–06:20 (good, 5.17 h)	42.9° 04:25	10.38	0%	127.2°
2027-10-30 Sat	89	—	unknown	01:05–05:20 (good, 5.25 h)	42.9° 03:20	10.42	2%	136.6°
2027-10-31 Sun	89	—	unknown	00:05–05:20 (good, 5.25 h)	42.9° 03:15	10.46	6%	143.8°
2027-11-01 Mon	89	—	unknown	00:00–05:20 (good, 5.33 h)	42.9° 03:15	10.49	12%	147.6°
2027-11-02 Tue	89	—	unknown	23:55–05:25 (good, 5.5 h)	42.9° 03:10	10.53	20%	147.2°
2027-11-03 Wed	89	—	unknown	23:50–05:25 (good, 5.58 h)	42.9° 03:05	10.57	28%	142.9°
2027-11-04 Thu	89	—	unknown	23:45–05:25 (good, 5.67 h)	42.9° 03:00	10.6	37%	136.1°
2027-11-05 Fri	89	—	unknown	23:45–05:25 (good, 5.67 h)	42.9° 03:00	10.64	46%	127.9°
2027-11-06 Sat	89	—	unknown	23:45–05:25 (good, 5.67 h)	42.9° 02:55	10.67	56%	118.7°
2027-11-07 Sun	89	—	unknown	23:45–05:30 (good, 5.75 h)	42.9° 02:50	10.7	65%	109.1°
2027-11-08 Mon	89	—	unknown	23:50–05:30 (good, 5.67 h)	42.9° 02:45	10.74	74%	99.0°
2027-11-09 Tue	89	—	unknown	00:00–05:30 (good, 5.5 h)	42.9° 02:40	10.77	82%	88.7°
2027-11-10 Wed	86	—	unknown	01:15–05:30 (good, 4.25 h)	42.9° 02:40	10.8	89%	78.2°
2027-11-11 Thu	75	—	unknown	04:00–05:35 (good, 1.58 h)	42.9° 02:35	10.83	94%	67.6°
2027-11-12 Fri	39	—	unknown	23:30–05:35 (marginal, 6.08 h)	42.9° 02:30	10.86	98%	57.1°
2027-11-13 Sat	25	—	unknown	00:50–05:35 (marginal, 4.75 h)	42.9° 02:25	10.89	100%	47.2°
2027-11-14 Sun	16	—	unknown	03:35–05:30 (marginal, 1.92 h)	42.9° 02:20	10.92	99%	38.7°
2027-11-15 Mon	12	—	unknown	—	42.9° 02:20	10.95	96%	33.1°
2027-11-16 Tue	15	—	unknown	23:30–23:55 (marginal, 0.42 h)	42.9° 02:15	10.98	90%	32.3°
2027-11-17 Wed	26	—	unknown	22:50–05:05 (marginal, 6.25 h)	42.9° 02:10	11.01	83%	36.7°
2027-11-18 Thu	43	—	unknown	22:25–05:30 (marginal, 7.08 h)	42.9° 02:05	11.04	73%	44.9°
2027-11-19 Fri	63	—	unknown	23:15–02:25 (good, 3.17 h)	42.9° 02:05	11.06	63%	55.1°
2027-11-20 Sat	82	—	unknown	22:45–04:45 (good, 6.0 h)	42.9° 02:00	11.09	51%	66.3°
2027-11-21 Sun	87	—	unknown	22:40–04:55 (good, 6.25 h)	42.9° 01:55	11.11	40%	78.0°
2027-11-22 Mon	89	—	unknown	22:35–05:00 (good, 6.42 h)	42.9° 01:50	11.14	29%	89.8°
2027-11-23 Tue	89	—	unknown	22:35–05:00 (good, 6.42 h)	42.9° 01:45	11.16	20%	101.5°
2027-11-24 Wed	89	—	unknown	22:30–05:00 (good, 6.5 h)	42.9° 01:45	11.19	12%	113.0°
2027-11-25 Thu	89	—	unknown	22:25–05:00 (good, 6.58 h)	42.9° 01:40	11.21	6%	123.8°
2027-11-26 Fri	89	—	unknown	22:20–04:55 (good, 6.58 h)	42.9° 01:35	11.23	2%	133.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-10-28&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.