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 HD 189733: 04-22 (66), 04-24 (66), 04-21 (65), 04-23 (65), 04-20 (64) — by astronomy; check the weather when the night is within four days.

2037-04-04astronomy score per night — click a bar for that night2037-05-03

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-04-04 Sat	23	—	unknown	05:00–05:25 (good, 0.42 h)	71.1° 08:30	7.9	75%	60.7°
2037-04-05 Sun	25	—	unknown	04:15–05:20 (good, 1.08 h)	71.1° 08:25	7.84	65%	53.0°
2037-04-06 Mon	29	—	unknown	03:40–05:20 (good, 1.67 h)	71.1° 08:20	7.79	55%	47.1°
2037-04-07 Tue	34	—	unknown	03:30–05:15 (good, 1.75 h)	71.1° 08:15	7.73	46%	43.4°
2037-04-08 Wed	43	—	unknown	03:10–05:15 (good, 2.08 h)	71.1° 08:10	7.67	36%	42.3°
2037-04-09 Thu	50	—	unknown	03:05–05:15 (good, 2.17 h)	71.1° 08:10	7.62	27%	44.0°
2037-04-10 Fri	53	—	unknown	03:05–05:10 (good, 2.08 h)	71.1° 08:05	7.56	19%	48.0°
2037-04-11 Sat	56	—	unknown	03:00–05:10 (good, 2.17 h)	71.1° 08:00	7.5	12%	53.8°
2037-04-12 Sun	56	—	unknown	02:55–05:05 (good, 2.17 h)	71.1° 07:55	7.45	7%	60.9°
2037-04-13 Mon	57	—	unknown	02:50–05:05 (good, 2.25 h)	71.1° 07:55	7.39	3%	68.8°
2037-04-14 Tue	59	—	unknown	02:45–05:05 (good, 2.33 h)	71.1° 07:50	7.33	1%	77.4°
2037-04-15 Wed	59	—	unknown	02:45–05:00 (good, 2.25 h)	71.1° 07:45	7.27	0%	86.3°
2037-04-16 Thu	60	—	unknown	02:40–05:00 (good, 2.33 h)	71.1° 07:40	7.22	2%	95.5°
2037-04-17 Fri	60	—	unknown	02:35–04:55 (good, 2.33 h)	71.1° 07:35	7.16	5%	104.7°
2037-04-18 Sat	62	—	unknown	02:30–04:55 (good, 2.42 h)	71.1° 07:35	7.1	11%	113.6°
2037-04-19 Sun	63	—	unknown	02:30–04:55 (good, 2.42 h)	71.1° 07:30	7.04	18%	122.0°
2037-04-20 Mon	64	—	unknown	02:25–04:50 (good, 2.42 h)	71.1° 07:25	6.98	27%	129.3°
2037-04-21 Tue	65	—	unknown	02:20–04:50 (good, 2.5 h)	71.1° 07:20	6.93	37%	134.8°
2037-04-22 Wed	66	—	unknown	02:20–04:50 (good, 2.5 h)	71.1° 07:15	6.87	48%	137.4°
2037-04-23 Thu	65	—	unknown	02:15–04:45 (good, 2.5 h)	71.1° 07:15	6.81	59%	136.5°
2037-04-24 Fri	66	—	unknown	02:15–04:45 (good, 2.5 h)	71.1° 07:10	6.75	70%	132.1°
2037-04-25 Sat	59	—	unknown	02:10–04:40 (good, 2.5 h)	71.1° 07:05	6.69	80%	124.9°
2037-04-26 Sun	56	—	unknown	02:10–04:40 (good, 2.5 h)	71.1° 07:00	6.64	89%	115.9°
2037-04-27 Mon	50	—	unknown	02:15–04:40 (good, 2.42 h)	71.1° 06:55	6.58	95%	105.7°
2037-04-28 Tue	42	—	unknown	02:30–04:35 (good, 2.08 h)	71.1° 06:55	6.52	99%	95.1°
2037-04-29 Wed	36	—	unknown	03:15–04:35 (good, 1.33 h)	71.1° 06:50	6.46	100%	84.4°
2037-04-30 Thu	32	—	unknown	03:55–04:35 (good, 0.67 h)	71.1° 06:45	6.4	98%	74.1°
2037-05-01 Fri	29	—	unknown	04:25–04:30 (good, 0.08 h)	71.1° 06:40	6.34	94%	64.5°
2037-05-02 Sat	29	—	unknown	01:15–04:30 (marginal, 3.25 h)	71.1° 06:40	6.29	88%	56.1°
2037-05-03 Sun	31	—	unknown	04:15–04:25 (good, 0.17 h)	71.1° 06:35	6.23	80%	49.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-04-04&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.