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: 12-22 (89), 01-05 (89), 01-06 (89), 01-07 (89), 01-08 (89) — by astronomy; check the weather when the night is within four days.

2028-12-22astronomy score per night — click a bar for that night2029-01-20

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-12-22 Fri	89	—	unknown	20:45–03:10 (good, 6.42 h)	42.9° 23:50	11.51	41%	94.1°
2028-12-23 Sat	88	—	unknown	20:50–03:05 (good, 6.25 h)	42.9° 23:45	11.5	50%	83.9°
2028-12-24 Sun	85	—	unknown	21:00–03:00 (good, 6.0 h)	42.9° 23:40	11.5	60%	73.7°
2028-12-25 Mon	75	—	unknown	22:45–02:55 (good, 4.17 h)	42.9° 23:40	11.5	69%	63.7°
2028-12-26 Tue	51	—	unknown	20:15–03:25 (marginal, 7.17 h)	42.9° 23:35	11.49	77%	54.0°
2028-12-27 Wed	34	—	unknown	20:30–03:10 (marginal, 6.67 h)	42.9° 23:30	11.49	85%	44.8°
2028-12-28 Thu	21	—	unknown	23:00–02:45 (marginal, 3.75 h)	42.9° 23:25	11.48	92%	36.9°
2028-12-29 Fri	12	—	unknown	—	42.9° 23:20	11.47	96%	31.6°
2028-12-30 Sat	10	—	unknown	—	42.9° 23:20	11.47	99%	30.7°
2028-12-31 Sun	14	—	unknown	20:25–21:00 (marginal, 0.58 h)	42.9° 23:15	11.46	100%	34.9°
2029-01-01 Mon	24	—	unknown	19:45–00:20 (marginal, 4.58 h)	42.9° 23:10	11.45	98%	42.9°
2029-01-02 Tue	41	—	unknown	19:25–02:10 (marginal, 6.75 h)	42.9° 23:05	11.44	94%	53.1°
2029-01-03 Wed	81	—	unknown	19:50–22:20 (good, 2.5 h)	42.9° 23:05	11.42	87%	64.6°
2029-01-04 Thu	87	—	unknown	19:45–01:00 (good, 5.25 h)	42.9° 23:00	11.41	78%	76.6°
2029-01-05 Fri	89	—	unknown	19:40–01:50 (good, 6.17 h)	42.9° 22:55	11.4	68%	88.8°
2029-01-06 Sat	89	—	unknown	19:35–02:00 (good, 6.42 h)	42.9° 22:50	11.38	57%	101.1°
2029-01-07 Sun	89	—	unknown	19:35–02:00 (good, 6.42 h)	42.9° 22:45	11.37	46%	113.0°
2029-01-08 Mon	89	—	unknown	19:30–02:00 (good, 6.5 h)	42.9° 22:45	11.35	35%	124.4°
2029-01-09 Tue	89	—	unknown	19:25–02:00 (good, 6.58 h)	42.9° 22:40	11.34	24%	134.8°
2029-01-10 Wed	89	—	unknown	19:20–01:55 (good, 6.58 h)	42.9° 22:35	11.32	16%	143.4°
2029-01-11 Thu	89	—	unknown	19:15–01:50 (good, 6.58 h)	42.9° 22:30	11.3	8%	148.7°
2029-01-12 Fri	89	—	unknown	19:15–01:45 (good, 6.5 h)	42.9° 22:25	11.28	4%	149.1°
2029-01-13 Sat	89	—	unknown	19:10–01:40 (good, 6.5 h)	42.9° 22:25	11.26	1%	144.7°
2029-01-14 Sun	89	—	unknown	19:05–01:40 (good, 6.58 h)	42.9° 22:20	11.24	0%	137.1°
2029-01-15 Mon	89	—	unknown	19:00–01:35 (good, 6.58 h)	42.9° 22:15	11.22	2%	127.9°
2029-01-16 Tue	89	—	unknown	19:00–01:30 (good, 6.5 h)	42.9° 22:10	11.2	5%	118.0°
2029-01-17 Wed	89	—	unknown	19:00–01:25 (good, 6.42 h)	42.9° 22:10	11.17	10%	107.8°
2029-01-18 Thu	89	—	unknown	19:00–01:25 (good, 6.42 h)	42.9° 22:05	11.15	17%	97.5°
2029-01-19 Fri	88	—	unknown	19:00–01:20 (good, 6.33 h)	42.9° 22:00	11.13	24%	87.2°
2029-01-20 Sat	86	—	unknown	19:00–01:15 (good, 6.25 h)	42.9° 21:55	11.1	33%	77.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-12-22&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.