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: 10-21 (89), 10-22 (89), 10-23 (89), 10-24 (89), 10-25 (89) — by astronomy; check the weather when the night is within four days.

2028-10-21astronomy score per night — click a bar for that night2028-11-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-10-21 Sat	89	—	unknown	01:40–06:10 (good, 4.5 h)	42.9° 04:55	10.1	19%	148.9°
2028-10-22 Sun	89	—	unknown	01:35–06:10 (good, 4.58 h)	42.9° 04:50	10.14	28%	148.5°
2028-10-23 Mon	89	—	unknown	01:30–06:15 (good, 4.75 h)	42.9° 04:45	10.18	37%	143.6°
2028-10-24 Tue	89	—	unknown	01:30–06:15 (good, 4.75 h)	42.9° 04:40	10.22	47%	136.0°
2028-10-25 Wed	89	—	unknown	01:25–06:15 (good, 4.83 h)	42.9° 04:40	10.26	57%	127.1°
2028-10-26 Thu	89	—	unknown	01:25–06:15 (good, 4.83 h)	42.9° 04:35	10.3	66%	117.6°
2028-10-27 Fri	89	—	unknown	01:30–06:20 (good, 4.83 h)	42.9° 04:30	10.33	75%	107.6°
2028-10-28 Sat	89	—	unknown	01:35–05:20 (good, 4.75 h)	42.9° 03:25	10.37	82%	97.6°
2028-10-29 Sun	88	—	unknown	01:00–05:20 (good, 4.33 h)	42.9° 03:20	10.41	89%	87.4°
2028-10-30 Mon	78	—	unknown	02:25–05:20 (good, 2.92 h)	42.9° 03:20	10.45	94%	77.2°
2028-10-31 Tue	45	—	unknown	23:55–05:20 (marginal, 5.42 h)	42.9° 03:15	10.48	98%	67.1°
2028-11-01 Wed	33	—	unknown	00:15–05:25 (marginal, 5.17 h)	42.9° 03:10	10.52	100%	57.2°
2028-11-02 Thu	23	—	unknown	01:15–05:25 (marginal, 4.17 h)	42.9° 03:05	10.56	100%	47.8°
2028-11-03 Fri	16	—	unknown	03:30–05:25 (marginal, 1.92 h)	42.9° 03:05	10.59	98%	39.4°
2028-11-04 Sat	13	—	unknown	—	42.9° 03:00	10.63	94%	33.1°
2028-11-05 Sun	14	—	unknown	00:15–00:20 (marginal, 0.08 h)	42.9° 02:55	10.66	88%	30.5°
2028-11-06 Mon	23	—	unknown	23:35–05:30 (marginal, 5.92 h)	42.9° 02:50	10.69	80%	32.7°
2028-11-07 Tue	37	—	unknown	23:10–05:30 (marginal, 6.33 h)	42.9° 02:45	10.73	71%	39.0°
2028-11-08 Wed	56	—	unknown	23:00–05:30 (marginal, 6.5 h)	42.9° 02:45	10.76	61%	48.0°
2028-11-09 Thu	71	—	unknown	23:25–05:05 (good, 5.67 h)	42.9° 02:40	10.79	50%	58.6°
2028-11-10 Fri	85	—	unknown	23:20–05:35 (good, 6.25 h)	42.9° 02:35	10.82	38%	70.2°
2028-11-11 Sat	88	—	unknown	23:15–05:35 (good, 6.33 h)	42.9° 02:30	10.86	28%	82.4°
2028-11-12 Sun	89	—	unknown	23:15–05:35 (good, 6.33 h)	42.9° 02:25	10.89	18%	94.9°
2028-11-13 Mon	89	—	unknown	23:10–05:35 (good, 6.42 h)	42.9° 02:25	10.92	10%	107.4°
2028-11-14 Tue	89	—	unknown	23:05–05:35 (good, 6.5 h)	42.9° 02:20	10.95	4%	119.6°
2028-11-15 Wed	89	—	unknown	23:00–05:35 (good, 6.58 h)	42.9° 02:15	10.97	1%	131.1°
2028-11-16 Thu	89	—	unknown	22:55–05:30 (good, 6.58 h)	42.9° 02:10	11.0	0%	140.9°
2028-11-17 Fri	89	—	unknown	22:55–05:25 (good, 6.5 h)	42.9° 02:05	11.03	2%	147.6°
2028-11-18 Sat	89	—	unknown	22:50–05:25 (good, 6.58 h)	42.9° 02:05	11.06	7%	149.4°
2028-11-19 Sun	89	—	unknown	22:45–05:20 (good, 6.58 h)	42.9° 02:00	11.08	14%	146.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-10-21&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.