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: 09-04 (17), 09-05 (17), 09-03 (16), 09-02 (15), 09-06 (15) — by astronomy; check the weather when the night is within four days.

2044-08-12astronomy score per night — click a bar for that night2044-09-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2044-08-12 Fri	0	—	unknown	—	42.9° 09:30	6.51	84%	78.4°
2044-08-13 Sat	0	—	unknown	—	42.9° 09:25	6.56	76%	67.8°
2044-08-14 Sun	0	—	unknown	—	42.9° 09:20	6.62	66%	57.5°
2044-08-15 Mon	0	—	unknown	—	42.9° 09:15	6.68	55%	47.8°
2044-08-16 Tue	0	—	unknown	—	42.9° 09:15	6.74	44%	39.7°
2044-08-17 Wed	0	—	unknown	—	42.9° 09:10	6.79	33%	34.7°
2044-08-18 Thu	0	—	unknown	—	42.9° 09:05	6.85	22%	34.3°
2044-08-19 Fri	1	—	unknown	—	42.9° 09:00	6.91	13%	39.1°
2044-08-20 Sat	1	—	unknown	—	42.9° 09:00	6.97	6%	47.6°
2044-08-21 Sun	1	—	unknown	—	42.9° 08:55	7.02	2%	58.1°
2044-08-22 Mon	1	—	unknown	—	42.9° 08:50	7.08	0%	69.6°
2044-08-23 Tue	2	—	unknown	05:30–05:40 (marginal, 0.17 h)	42.9° 08:45	7.14	1%	81.4°
2044-08-24 Wed	3	—	unknown	05:30–05:40 (marginal, 0.17 h)	42.9° 08:40	7.2	5%	93.2°
2044-08-25 Thu	4	—	unknown	05:25–05:40 (marginal, 0.25 h)	42.9° 08:40	7.25	10%	104.5°
2044-08-26 Fri	4	—	unknown	04:50–05:05 (marginal, 0.25 h)	42.9° 08:35	7.31	18%	115.2°
2044-08-27 Sat	5	—	unknown	04:45–05:05 (marginal, 0.33 h)	42.9° 08:30	7.37	27%	125.0°
2044-08-28 Sun	7	—	unknown	05:10–05:45 (marginal, 0.58 h)	42.9° 08:25	7.42	36%	133.7°
2044-08-29 Mon	9	—	unknown	04:35–05:45 (marginal, 1.17 h)	42.9° 08:20	7.48	46%	140.6°
2044-08-30 Tue	9	—	unknown	05:05–05:10 (good, 0.08 h)	42.9° 08:20	7.54	55%	145.0°
2044-08-31 Wed	10	—	unknown	05:00–05:10 (good, 0.17 h)	42.9° 08:15	7.59	64%	146.1°
2044-09-01 Thu	13	—	unknown	04:55–05:15 (good, 0.33 h)	42.9° 08:10	7.65	73%	143.6°
2044-09-02 Fri	15	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.7	81%	138.3°
2044-09-03 Sat	16	—	unknown	04:50–05:15 (good, 0.42 h)	42.9° 08:05	7.76	88%	130.9°
2044-09-04 Sun	17	—	unknown	04:45–05:15 (good, 0.5 h)	42.9° 08:00	7.81	94%	122.2°
2044-09-05 Mon	17	—	unknown	04:55–05:20 (good, 0.42 h)	42.9° 07:55	7.87	98%	112.6°
2044-09-06 Tue	15	—	unknown	05:00–05:20 (good, 0.33 h)	42.9° 07:50	7.92	100%	102.5°
2044-09-07 Wed	13	—	unknown	05:15–05:20 (good, 0.08 h)	42.9° 07:45	7.98	100%	92.0°
2044-09-08 Thu	10	—	unknown	04:10–05:20 (marginal, 1.17 h)	42.9° 07:45	8.03	98%	81.2°
2044-09-09 Fri	9	—	unknown	04:15–05:25 (marginal, 1.17 h)	42.9° 07:40	8.09	94%	70.4°
2044-09-10 Sat	8	—	unknown	04:20–05:25 (marginal, 1.08 h)	42.9° 07:35	8.14	87%	59.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2044-08-12&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.