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: 10-26 (89), 10-27 (89), 10-28 (89), 10-29 (89), 10-30 (89) — by astronomy; check the weather when the night is within four days.

2027-10-17astronomy score per night — click a bar for that night2027-11-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-10-17 Sun	15	—	unknown	03:05–06:05 (marginal, 3.0 h)	42.9° 05:10	9.9	94%	44.3°
2027-10-18 Mon	13	—	unknown	03:15–06:05 (marginal, 2.83 h)	42.9° 05:10	9.94	88%	36.7°
2027-10-19 Tue	15	—	unknown	02:05–06:10 (marginal, 4.08 h)	42.9° 05:05	9.98	80%	32.5°
2027-10-20 Wed	23	—	unknown	01:35–06:10 (marginal, 4.58 h)	42.9° 05:00	10.02	70%	33.2°
2027-10-21 Thu	36	—	unknown	01:15–06:10 (marginal, 4.92 h)	42.9° 04:55	10.07	59%	38.6°
2027-10-22 Fri	53	—	unknown	02:05–06:10 (good, 4.08 h)	42.9° 04:55	10.11	48%	47.2°
2027-10-23 Sat	70	—	unknown	01:45–06:15 (good, 4.5 h)	42.9° 04:50	10.15	36%	57.6°
2027-10-24 Sun	84	—	unknown	01:30–06:15 (good, 4.75 h)	42.9° 04:45	10.19	26%	69.1°
2027-10-25 Mon	88	—	unknown	01:25–06:15 (good, 4.83 h)	42.9° 04:40	10.23	16%	81.0°
2027-10-26 Tue	89	—	unknown	01:25–06:15 (good, 4.83 h)	42.9° 04:35	10.27	9%	93.1°
2027-10-27 Wed	89	—	unknown	01:20–06:15 (good, 4.92 h)	42.9° 04:35	10.31	4%	105.0°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-10-17&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.