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: 09-21 (47), 09-20 (45), 09-19 (43), 09-18 (42), 09-17 (39) — by astronomy; check the weather when the night is within four days.

2036-08-23astronomy score per night — click a bar for that night2036-09-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2036-08-23 Sat	2	—	unknown	05:30–05:35 (marginal, 0.08 h)	42.9° 08:45	7.13	7%	99.8°
2036-08-24 Sun	3	—	unknown	05:30–05:40 (marginal, 0.17 h)	42.9° 08:40	7.19	14%	112.8°
2036-08-25 Mon	4	—	unknown	05:25–05:40 (marginal, 0.25 h)	42.9° 08:40	7.25	23%	125.1°
2036-08-26 Tue	4	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.31	33%	136.4°
2036-08-27 Wed	5	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.36	43%	146.1°
2036-08-28 Thu	7	—	unknown	05:10–05:45 (marginal, 0.58 h)	42.9° 08:25	7.42	53%	153.1°
2036-08-29 Fri	9	—	unknown	04:35–05:45 (marginal, 1.17 h)	42.9° 08:20	7.48	63%	155.6°
2036-08-30 Sat	9	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:20	7.53	72%	152.7°
2036-08-31 Sun	10	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.59	80%	145.8°
2036-09-01 Mon	13	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:10	7.64	87%	137.0°
2036-09-02 Tue	15	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.7	93%	127.2°
2036-09-03 Wed	14	—	unknown	05:00–05:15 (good, 0.25 h)	42.9° 08:00	7.75	97%	116.8°
2036-09-04 Thu	13	—	unknown	05:00–05:15 (good, 0.25 h)	42.9° 08:00	7.81	99%	106.2°
2036-09-05 Fri	12	—	unknown	05:10–05:20 (good, 0.17 h)	42.9° 07:55	7.86	100%	95.3°
2036-09-06 Sat	11	—	unknown	04:15–05:20 (marginal, 1.08 h)	42.9° 07:50	7.92	99%	84.3°
2036-09-07 Sun	9	—	unknown	04:15–05:20 (marginal, 1.08 h)	42.9° 07:45	7.97	96%	73.2°
2036-09-08 Mon	7	—	unknown	04:20–05:20 (marginal, 1.0 h)	42.9° 07:45	8.03	91%	62.1°
2036-09-09 Tue	7	—	unknown	04:25–05:25 (marginal, 1.0 h)	42.9° 07:40	8.08	84%	51.2°
2036-09-10 Wed	7	—	unknown	04:20–05:25 (marginal, 1.08 h)	42.9° 07:35	8.14	76%	40.7°
2036-09-11 Thu	8	—	unknown	04:10–05:25 (marginal, 1.25 h)	42.9° 07:30	8.19	66%	31.6°
2036-09-12 Fri	11	—	unknown	03:55–05:25 (marginal, 1.5 h)	42.9° 07:25	8.24	56%	25.4°
2036-09-13 Sat	16	—	unknown	03:40–05:30 (marginal, 1.83 h)	42.9° 07:25	8.3	44%	25.2°
2036-09-14 Sun	22	—	unknown	04:30–05:30 (good, 1.0 h)	42.9° 07:20	8.35	34%	31.4°
2036-09-15 Mon	28	—	unknown	04:15–05:30 (good, 1.25 h)	42.9° 07:15	8.4	23%	41.6°
2036-09-16 Tue	34	—	unknown	04:00–05:30 (good, 1.5 h)	42.9° 07:10	8.45	14%	53.6°
2036-09-17 Wed	39	—	unknown	03:55–05:35 (good, 1.67 h)	42.9° 07:05	8.51	7%	66.7°
2036-09-18 Thu	42	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 07:05	8.56	2%	80.1°
2036-09-19 Fri	43	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 07:00	8.61	0%	93.7°
2036-09-20 Sat	45	—	unknown	03:40–05:35 (good, 1.92 h)	42.9° 06:55	8.66	1%	107.1°
2036-09-21 Sun	47	—	unknown	03:40–05:40 (good, 2.0 h)	42.9° 06:50	8.71	5%	119.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2036-08-23&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.