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: 09-26 (55), 09-25 (53), 09-24 (52), 09-23 (50), 09-22 (48) — by astronomy; check the weather when the night is within four days.

2033-08-28astronomy score per night — click a bar for that night2033-09-26

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2033-08-28 Sun	7	—	unknown	04:40–05:05 (marginal, 0.42 h)	42.9° 08:25	7.4	14%	113.9°
2033-08-29 Mon	8	—	unknown	04:40–05:45 (marginal, 1.08 h)	42.9° 08:25	7.46	21%	124.4°
2033-08-30 Tue	9	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:20	7.52	30%	134.5°
2033-08-31 Wed	10	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.57	39%	143.9°
2033-09-01 Thu	12	—	unknown	04:55–05:10 (good, 0.25 h)	42.9° 08:10	7.63	48%	151.7°
2033-09-02 Fri	15	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:05	7.68	58%	156.0°
2033-09-03 Sat	16	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.74	68%	154.5°
2033-09-04 Sun	17	—	unknown	04:45–05:15 (good, 0.5 h)	42.9° 08:00	7.79	78%	147.6°
2033-09-05 Mon	21	—	unknown	04:40–05:20 (good, 0.67 h)	42.9° 07:55	7.85	86%	137.4°
2033-09-06 Tue	21	—	unknown	04:40–05:20 (good, 0.67 h)	42.9° 07:50	7.9	93%	125.4°
2033-09-07 Wed	18	—	unknown	04:45–05:20 (good, 0.58 h)	42.9° 07:50	7.96	98%	112.5°
2033-09-08 Thu	15	—	unknown	04:55–05:20 (good, 0.42 h)	42.9° 07:45	8.01	100%	98.9°
2033-09-09 Fri	13	—	unknown	04:05–05:25 (marginal, 1.33 h)	42.9° 07:40	8.07	99%	85.1°
2033-09-10 Sat	10	—	unknown	04:10–05:25 (marginal, 1.25 h)	42.9° 07:35	8.12	95%	71.3°
2033-09-11 Sun	8	—	unknown	04:15–05:25 (marginal, 1.17 h)	42.9° 07:30	8.18	88%	57.9°
2033-09-12 Mon	7	—	unknown	04:15–05:25 (marginal, 1.17 h)	42.9° 07:30	8.23	80%	45.3°
2033-09-13 Tue	8	—	unknown	04:10–05:30 (marginal, 1.33 h)	42.9° 07:25	8.28	70%	34.2°
2033-09-14 Wed	11	—	unknown	03:50–05:30 (marginal, 1.67 h)	42.9° 07:20	8.34	59%	26.2°
2033-09-15 Thu	16	—	unknown	03:35–05:30 (marginal, 1.92 h)	42.9° 07:15	8.39	48%	23.8°
2033-09-16 Fri	21	—	unknown	04:30–05:30 (good, 1.0 h)	42.9° 07:10	8.44	37%	27.9°
2033-09-17 Sat	28	—	unknown	04:10–05:35 (good, 1.42 h)	42.9° 07:10	8.49	28%	36.1°
2033-09-18 Sun	34	—	unknown	04:00–05:35 (good, 1.58 h)	42.9° 07:05	8.54	19%	46.0°
2033-09-19 Mon	40	—	unknown	03:45–05:35 (good, 1.83 h)	42.9° 07:00	8.6	12%	56.6°
2033-09-20 Tue	44	—	unknown	03:40–05:35 (good, 1.92 h)	42.9° 06:55	8.65	6%	67.5°
2033-09-21 Wed	47	—	unknown	03:40–05:40 (good, 2.0 h)	42.9° 06:55	8.7	2%	78.4°
2033-09-22 Thu	48	—	unknown	03:35–05:40 (good, 2.08 h)	42.9° 06:50	8.75	0%	89.4°
2033-09-23 Fri	50	—	unknown	03:30–05:40 (good, 2.17 h)	42.9° 06:45	8.8	0%	100.2°
2033-09-24 Sat	52	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:40	8.85	2%	111.0°
2033-09-25 Sun	53	—	unknown	03:25–05:40 (good, 2.25 h)	42.9° 06:35	8.9	5%	121.6°
2033-09-26 Mon	55	—	unknown	03:20–05:45 (good, 2.42 h)	42.9° 06:35	8.95	10%	131.8°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2033-08-28&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.