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: 01-20 (89), 01-21 (89), 01-22 (89), 01-23 (89), 02-06 (89) — by astronomy; check the weather when the night is within four days.

2034-01-20astronomy score per night — click a bar for that night2034-02-18

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2034-01-20 Fri	89	—	unknown	19:00–01:15 (good, 6.25 h)	42.9° 21:55	11.11	0%	131.3°
2034-01-21 Sat	89	—	unknown	19:00–01:10 (good, 6.17 h)	42.9° 21:55	11.08	3%	119.3°
2034-01-22 Sun	89	—	unknown	19:05–01:10 (good, 6.08 h)	42.9° 21:50	11.05	8%	106.8°
2034-01-23 Mon	89	—	unknown	19:05–01:05 (good, 6.0 h)	42.9° 21:45	11.03	15%	93.9°
2034-01-24 Tue	88	—	unknown	19:05–01:00 (good, 5.92 h)	42.9° 21:40	11.0	24%	81.0°
2034-01-25 Wed	85	—	unknown	19:05–00:55 (good, 5.83 h)	42.9° 21:35	10.97	34%	68.1°
2034-01-26 Thu	72	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:35	10.94	45%	55.5°
2034-01-27 Fri	55	—	unknown	22:05–00:15 (good, 2.17 h)	42.9° 21:30	10.91	57%	43.6°
2034-01-28 Sat	36	—	unknown	19:10–01:05 (marginal, 5.92 h)	42.9° 21:25	10.88	68%	33.0°
2034-01-29 Sun	23	—	unknown	19:10–00:45 (marginal, 5.58 h)	42.9° 21:20	10.85	78%	25.5°
2034-01-30 Mon	15	—	unknown	19:10–00:10 (marginal, 5.0 h)	42.9° 21:20	10.82	86%	24.0°
2034-01-31 Tue	12	—	unknown	19:15–19:35 (marginal, 0.33 h)	42.9° 21:15	10.79	93%	29.4°
2034-02-01 Wed	16	—	unknown	19:15–21:35 (marginal, 2.33 h)	42.9° 21:10	10.76	97%	38.6°
2034-02-02 Thu	24	—	unknown	19:15–23:55 (marginal, 4.67 h)	42.9° 21:05	10.72	100%	49.4°
2034-02-03 Fri	36	—	unknown	19:15–00:15 (marginal, 5.0 h)	42.9° 21:00	10.69	100%	60.8°
2034-02-04 Sat	50	—	unknown	19:20–20:55 (good, 1.58 h)	42.9° 21:00	10.65	98%	72.3°
2034-02-05 Sun	81	—	unknown	19:20–22:50 (good, 3.5 h)	42.9° 20:55	10.62	94%	83.8°
2034-02-06 Mon	89	—	unknown	19:20–23:40 (good, 4.33 h)	42.9° 20:50	10.58	88%	95.0°
2034-02-07 Tue	89	—	unknown	19:20–23:50 (good, 4.5 h)	42.9° 20:45	10.55	81%	106.1°
2034-02-08 Wed	89	—	unknown	19:20–23:55 (good, 4.58 h)	42.9° 20:40	10.51	73%	116.9°
2034-02-09 Thu	89	—	unknown	19:25–23:55 (good, 4.5 h)	42.9° 20:40	10.47	64%	127.3°
2034-02-10 Fri	89	—	unknown	19:25–23:55 (good, 4.5 h)	42.9° 20:35	10.44	55%	137.2°
2034-02-11 Sat	89	—	unknown	19:25–23:50 (good, 4.42 h)	42.9° 20:30	10.4	46%	146.3°
2034-02-12 Sun	89	—	unknown	19:25–23:45 (good, 4.33 h)	42.9° 20:25	10.36	36%	153.3°
2034-02-13 Mon	89	—	unknown	19:30–23:40 (good, 4.17 h)	42.9° 20:25	10.32	27%	156.4°
2034-02-14 Tue	89	—	unknown	19:30–23:40 (good, 4.17 h)	42.9° 20:20	10.28	18%	153.6°
2034-02-15 Wed	88	—	unknown	19:30–23:35 (good, 4.08 h)	42.9° 20:15	10.24	11%	146.1°
2034-02-16 Thu	86	—	unknown	19:30–23:30 (good, 4.0 h)	42.9° 20:10	10.2	5%	135.8°
2034-02-17 Fri	85	—	unknown	19:30–23:25 (good, 3.92 h)	42.9° 20:05	10.16	2%	124.1°
2034-02-18 Sat	83	—	unknown	19:35–23:20 (good, 3.75 h)	42.9° 20:05	10.12	0%	111.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2034-01-20&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.