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: 10-11 (80), 10-10 (79), 10-09 (78), 10-08 (75), 10-07 (74) — by astronomy; check the weather when the night is within four days.

2037-09-12astronomy score per night — click a bar for that night2037-10-11

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-09-12 Sat	31	—	unknown	04:15–05:25 (good, 1.17 h)	42.9° 07:30	8.23	15%	129.0°
2037-09-13 Sun	33	—	unknown	04:10–05:30 (good, 1.33 h)	42.9° 07:25	8.28	24%	140.3°
2037-09-14 Mon	35	—	unknown	04:05–05:30 (good, 1.42 h)	42.9° 07:20	8.34	34%	149.3°
2037-09-15 Tue	36	—	unknown	04:00–05:30 (good, 1.5 h)	42.9° 07:15	8.39	45%	154.0°
2037-09-16 Wed	38	—	unknown	04:00–05:30 (good, 1.5 h)	42.9° 07:10	8.44	55%	152.8°
2037-09-17 Thu	40	—	unknown	03:55–05:35 (good, 1.67 h)	42.9° 07:10	8.49	65%	146.6°
2037-09-18 Fri	42	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 07:05	8.55	74%	137.9°
2037-09-19 Sat	43	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 07:00	8.6	82%	128.1°
2037-09-20 Sun	44	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 06:55	8.65	89%	117.8°
2037-09-21 Mon	43	—	unknown	03:55–05:40 (good, 1.75 h)	42.9° 06:55	8.7	94%	107.3°
2037-09-22 Tue	33	—	unknown	04:00–05:40 (good, 1.67 h)	42.9° 06:50	8.75	98%	96.7°
2037-09-23 Wed	28	—	unknown	04:35–05:40 (good, 1.08 h)	42.9° 06:45	8.8	100%	86.0°
2037-09-24 Thu	22	—	unknown	03:10–05:40 (marginal, 2.5 h)	42.9° 06:40	8.85	100%	75.4°
2037-09-25 Fri	17	—	unknown	03:20–05:40 (marginal, 2.33 h)	42.9° 06:35	8.9	98%	64.9°
2037-09-26 Sat	14	—	unknown	03:25–05:45 (marginal, 2.33 h)	42.9° 06:35	8.95	94%	54.6°
2037-09-27 Sun	11	—	unknown	03:35–05:45 (marginal, 2.17 h)	42.9° 06:30	9.0	89%	44.8°
2037-09-28 Mon	10	—	unknown	03:30–05:45 (marginal, 2.25 h)	42.9° 06:25	9.05	83%	35.9°
2037-09-29 Tue	11	—	unknown	03:15–05:45 (marginal, 2.5 h)	42.9° 06:20	9.1	75%	28.9°
2037-09-30 Wed	16	—	unknown	02:55–05:50 (marginal, 2.92 h)	42.9° 06:15	9.15	66%	25.9°
2037-10-01 Thu	22	—	unknown	02:35–05:50 (marginal, 3.25 h)	42.9° 06:15	9.2	55%	28.3°
2037-10-02 Fri	33	—	unknown	03:55–05:50 (good, 1.92 h)	42.9° 06:10	9.24	45%	35.5°
2037-10-03 Sat	44	—	unknown	03:10–05:50 (good, 2.67 h)	42.9° 06:05	9.29	34%	45.5°
2037-10-04 Sun	55	—	unknown	02:55–05:50 (good, 2.92 h)	42.9° 06:00	9.34	24%	57.1°
2037-10-05 Mon	65	—	unknown	02:45–05:55 (good, 3.17 h)	42.9° 06:00	9.38	15%	69.7°
2037-10-06 Tue	71	—	unknown	02:40–05:55 (good, 3.25 h)	42.9° 05:55	9.43	7%	83.0°
2037-10-07 Wed	74	—	unknown	02:35–05:55 (good, 3.33 h)	42.9° 05:50	9.48	2%	96.6°
2037-10-08 Thu	75	—	unknown	02:30–05:55 (good, 3.42 h)	42.9° 05:45	9.52	0%	110.1°
2037-10-09 Fri	78	—	unknown	02:30–06:00 (good, 3.5 h)	42.9° 05:40	9.57	1%	123.4°
2037-10-10 Sat	79	—	unknown	02:25–06:00 (good, 3.58 h)	42.9° 05:40	9.61	5%	135.6°
2037-10-11 Sun	80	—	unknown	02:20–06:00 (good, 3.67 h)	42.9° 05:35	9.66	11%	146.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-09-12&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.