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: 09-30 (63), 10-01 (62), 09-29 (60), 09-28 (59), 10-02 (58) — by astronomy; check the weather when the night is within four days.

2036-09-07astronomy score per night — click a bar for that night2036-10-06

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2036-09-22 Mon	48	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:50	8.76	11%	131.9°
2036-09-23 Tue	50	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:45	8.81	19%	142.6°
2036-09-24 Wed	52	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:40	8.86	27%	151.0°
2036-09-25 Thu	55	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:35	8.91	37%	155.3°
2036-09-26 Fri	56	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:30	8.96	47%	153.9°
2036-09-27 Sat	57	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:30	9.01	56%	148.0°
2036-09-28 Sun	59	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:25	9.06	66%	139.6°
2036-09-29 Mon	60	—	unknown	03:05–05:45 (good, 2.67 h)	42.9° 06:20	9.11	74%	130.0°
2036-09-30 Tue	63	—	unknown	03:05–05:50 (good, 2.75 h)	42.9° 06:15	9.16	82%	119.9°
2036-10-01 Wed	62	—	unknown	03:10–05:50 (good, 2.67 h)	42.9° 06:10	9.21	89%	109.3°
2036-10-02 Thu	58	—	unknown	03:20–05:50 (good, 2.5 h)	42.9° 06:10	9.25	94%	98.5°
2036-10-03 Fri	42	—	unknown	03:45–05:50 (good, 2.08 h)	42.9° 06:05	9.3	98%	87.4°
2036-10-04 Sat	33	—	unknown	05:10–05:55 (good, 0.75 h)	42.9° 06:00	9.35	100%	76.3°
2036-10-05 Sun	25	—	unknown	02:40–05:55 (marginal, 3.25 h)	42.9° 05:55	9.4	100%	65.1°
2036-10-06 Mon	18	—	unknown	02:50–05:55 (marginal, 3.08 h)	42.9° 05:55	9.44	98%	54.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2036-09-07&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.