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: 09-23 (36), 09-10 (27), 09-22 (27), 09-09 (26), 09-08 (24) — by astronomy; check the weather when the night is within four days.

2038-08-25astronomy score per night — click a bar for that night2038-09-23

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-08-25 Wed	2	—	unknown	04:55–05:00 (marginal, 0.08 h)	42.9° 08:40	7.22	22%	31.1°
2038-08-26 Thu	4	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.28	14%	38.7°
2038-08-27 Fri	5	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.33	8%	48.6°
2038-08-28 Sat	6	—	unknown	05:15–05:45 (marginal, 0.5 h)	42.9° 08:30	7.39	3%	59.9°
2038-08-29 Sun	8	—	unknown	04:40–05:45 (marginal, 1.08 h)	42.9° 08:25	7.45	0%	72.1°
2038-08-30 Mon	9	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:20	7.5	0%	84.8°
2038-08-31 Tue	10	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.56	3%	97.7°
2038-09-01 Wed	12	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:10	7.62	9%	110.7°
2038-09-02 Thu	14	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:10	7.67	17%	123.2°
2038-09-03 Fri	15	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.73	26%	134.9°
2038-09-04 Sat	17	—	unknown	04:45–05:15 (good, 0.5 h)	42.9° 08:00	7.78	37%	144.9°
2038-09-05 Sun	19	—	unknown	04:40–05:15 (good, 0.58 h)	42.9° 07:55	7.84	48%	151.4°
2038-09-06 Mon	21	—	unknown	04:40–05:20 (good, 0.67 h)	42.9° 07:55	7.89	60%	152.3°
2038-09-07 Tue	23	—	unknown	04:35–05:20 (good, 0.75 h)	42.9° 07:50	7.95	70%	147.4°
2038-09-08 Wed	24	—	unknown	04:30–05:20 (good, 0.83 h)	42.9° 07:45	8.0	79%	139.0°
2038-09-09 Thu	26	—	unknown	04:25–05:25 (good, 1.0 h)	42.9° 07:40	8.06	87%	128.9°
2038-09-10 Fri	27	—	unknown	04:25–05:25 (good, 1.0 h)	42.9° 07:35	8.11	93%	118.1°
2038-09-11 Sat	23	—	unknown	04:35–05:25 (good, 0.83 h)	42.9° 07:35	8.16	97%	107.1°
2038-09-12 Sun	19	—	unknown	04:40–05:25 (good, 0.75 h)	42.9° 07:30	8.22	100%	96.0°
2038-09-13 Mon	17	—	unknown	05:20–05:30 (good, 0.17 h)	42.9° 07:25	8.27	100%	85.1°
2038-09-14 Tue	14	—	unknown	03:50–05:30 (marginal, 1.67 h)	42.9° 07:20	8.32	98%	74.3°
2038-09-15 Wed	11	—	unknown	03:55–05:30 (marginal, 1.58 h)	42.9° 07:15	8.38	94%	63.9°
2038-09-16 Thu	9	—	unknown	04:00–05:30 (marginal, 1.5 h)	42.9° 07:15	8.43	89%	53.9°
2038-09-17 Fri	9	—	unknown	04:05–05:35 (marginal, 1.5 h)	42.9° 07:10	8.48	83%	44.5°
2038-09-18 Sat	9	—	unknown	03:55–05:35 (marginal, 1.67 h)	42.9° 07:05	8.53	75%	36.2°
2038-09-19 Sun	11	—	unknown	03:45–05:35 (marginal, 1.83 h)	42.9° 07:00	8.59	67%	30.0°
2038-09-20 Mon	14	—	unknown	03:25–05:35 (marginal, 2.17 h)	42.9° 07:00	8.64	57%	27.4°
2038-09-21 Tue	20	—	unknown	03:10–05:35 (marginal, 2.42 h)	42.9° 06:55	8.69	48%	29.5°
2038-09-22 Wed	27	—	unknown	04:05–05:40 (good, 1.58 h)	42.9° 06:50	8.74	38%	35.7°
2038-09-23 Thu	36	—	unknown	03:45–05:40 (good, 1.92 h)	42.9° 06:45	8.79	28%	44.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-08-25&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.