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: 10-15 (87), 10-14 (82), 10-13 (71), 09-28 (59), 09-29 (58) — by astronomy; check the weather when the night is within four days.

2028-09-16astronomy score per night — click a bar for that night2028-10-15

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-09-16 Sat	38	—	unknown	03:55–05:30 (good, 1.58 h)	42.9° 07:10	8.45	5%	67.0°
2028-09-17 Sun	41	—	unknown	03:55–05:35 (good, 1.67 h)	42.9° 07:05	8.5	1%	79.8°
2028-09-18 Mon	42	—	unknown	03:50–05:35 (good, 1.75 h)	42.9° 07:05	8.56	0%	92.8°
2028-09-19 Tue	43	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 07:00	8.61	2%	105.8°
2028-09-20 Wed	45	—	unknown	03:40–05:35 (good, 1.92 h)	42.9° 06:55	8.66	7%	118.3°
2028-09-21 Thu	48	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:50	8.71	14%	129.7°
2028-09-22 Fri	48	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:50	8.76	23%	139.5°
2028-09-23 Sat	50	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:45	8.81	33%	146.4°
2028-09-24 Sun	52	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:40	8.86	44%	149.1°
2028-09-25 Mon	55	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:35	8.91	54%	147.0°
2028-09-26 Tue	56	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:30	8.96	64%	141.3°
2028-09-27 Wed	57	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:30	9.01	73%	133.4°
2028-09-28 Thu	59	—	unknown	03:10–05:45 (good, 2.58 h)	42.9° 06:25	9.06	81%	124.3°
2028-09-29 Fri	58	—	unknown	03:15–05:45 (good, 2.5 h)	42.9° 06:20	9.11	88%	114.7°
2028-09-30 Sat	57	—	unknown	03:20–05:50 (good, 2.5 h)	42.9° 06:15	9.16	93%	104.8°
2028-10-01 Sun	43	—	unknown	03:30–05:50 (good, 2.33 h)	42.9° 06:10	9.2	97%	94.7°
2028-10-02 Mon	35	—	unknown	04:35–05:50 (good, 1.25 h)	42.9° 06:10	9.25	99%	84.5°
2028-10-03 Tue	27	—	unknown	02:40–05:50 (marginal, 3.17 h)	42.9° 06:05	9.3	100%	74.4°
2028-10-04 Wed	21	—	unknown	02:50–05:55 (marginal, 3.08 h)	42.9° 06:00	9.35	98%	64.4°
2028-10-05 Thu	16	—	unknown	03:00–05:55 (marginal, 2.92 h)	42.9° 05:55	9.39	95%	54.7°
2028-10-06 Fri	13	—	unknown	03:05–05:55 (marginal, 2.83 h)	42.9° 05:55	9.44	90%	45.6°
2028-10-07 Sat	12	—	unknown	03:00–05:55 (marginal, 2.92 h)	42.9° 05:50	9.49	84%	37.8°
2028-10-08 Sun	14	—	unknown	02:40–05:55 (marginal, 3.25 h)	42.9° 05:45	9.53	76%	32.3°
2028-10-09 Mon	20	—	unknown	02:15–06:00 (marginal, 3.75 h)	42.9° 05:40	9.58	66%	30.8°
2028-10-10 Tue	29	—	unknown	01:55–06:00 (marginal, 4.08 h)	42.9° 05:35	9.62	56%	34.0°
2028-10-11 Wed	43	—	unknown	02:50–06:00 (good, 3.17 h)	42.9° 05:35	9.67	45%	41.2°
2028-10-12 Thu	57	—	unknown	02:30–06:00 (good, 3.5 h)	42.9° 05:30	9.71	34%	50.8°
2028-10-13 Fri	71	—	unknown	02:10–06:05 (good, 3.92 h)	42.9° 05:25	9.76	24%	62.0°
2028-10-14 Sat	82	—	unknown	02:05–06:05 (good, 4.0 h)	42.9° 05:20	9.8	15%	74.2°
2028-10-15 Sun	87	—	unknown	02:05–06:05 (good, 4.0 h)	42.9° 05:15	9.84	7%	86.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-09-16&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.