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: 04-30 (73), 05-01 (72), 05-02 (72), 04-27 (71), 04-28 (71) — by astronomy; check the weather when the night is within four days.

2031-04-03astronomy score per night — click a bar for that night2031-05-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2031-04-03 Thu	45	—	unknown	03:40–05:25 (good, 1.75 h)	71.1° 08:35	7.98	84%	139.4°
2031-04-04 Fri	46	—	unknown	03:35–05:25 (good, 1.83 h)	71.1° 08:30	7.93	91%	133.5°
2031-04-05 Sat	41	—	unknown	03:35–05:20 (good, 1.75 h)	71.1° 08:25	7.87	96%	125.4°
2031-04-06 Sun	39	—	unknown	03:35–05:20 (good, 1.75 h)	71.1° 08:20	7.82	99%	116.0°
2031-04-07 Mon	35	—	unknown	03:35–05:20 (good, 1.75 h)	71.1° 08:20	7.76	100%	105.5°
2031-04-08 Tue	31	—	unknown	03:40–05:15 (good, 1.58 h)	71.1° 08:15	7.7	98%	94.5°
2031-04-09 Wed	28	—	unknown	04:10–05:15 (good, 1.08 h)	71.1° 08:10	7.65	94%	83.2°
2031-04-10 Thu	25	—	unknown	04:35–05:10 (good, 0.58 h)	71.1° 08:05	7.59	87%	72.0°
2031-04-11 Fri	25	—	unknown	04:40–05:10 (good, 0.5 h)	71.1° 08:00	7.53	78%	61.3°
2031-04-12 Sat	27	—	unknown	04:10–05:10 (good, 1.0 h)	71.1° 08:00	7.48	68%	51.5°
2031-04-13 Sun	31	—	unknown	03:20–05:05 (good, 1.75 h)	71.1° 07:55	7.42	57%	43.5°
2031-04-14 Mon	37	—	unknown	03:05–05:05 (good, 2.0 h)	71.1° 07:50	7.36	46%	38.4°
2031-04-15 Tue	47	—	unknown	02:45–05:00 (good, 2.25 h)	71.1° 07:45	7.31	34%	37.4°
2031-04-16 Wed	53	—	unknown	02:40–05:00 (good, 2.33 h)	71.1° 07:45	7.25	24%	40.7°
2031-04-17 Thu	59	—	unknown	02:35–05:00 (good, 2.42 h)	71.1° 07:40	7.19	16%	47.2°
2031-04-18 Fri	61	—	unknown	02:35–04:55 (good, 2.33 h)	71.1° 07:35	7.13	8%	55.6°
2031-04-19 Sat	63	—	unknown	02:30–04:55 (good, 2.42 h)	71.1° 07:30	7.07	4%	65.1°
2031-04-20 Sun	64	—	unknown	02:25–04:55 (good, 2.5 h)	71.1° 07:25	7.02	1%	75.1°
2031-04-21 Mon	64	—	unknown	02:20–04:50 (good, 2.5 h)	71.1° 07:25	6.96	0%	85.2°
2031-04-22 Tue	66	—	unknown	02:20–04:50 (good, 2.5 h)	71.1° 07:20	6.9	2%	95.3°
2031-04-23 Wed	66	—	unknown	02:15–04:45 (good, 2.5 h)	71.1° 07:15	6.84	5%	105.0°
2031-04-24 Thu	67	—	unknown	02:10–04:45 (good, 2.58 h)	71.1° 07:10	6.78	10%	114.4°
2031-04-25 Fri	69	—	unknown	02:05–04:45 (good, 2.67 h)	71.1° 07:05	6.72	16%	123.0°
2031-04-26 Sat	69	—	unknown	02:00–04:40 (good, 2.67 h)	71.1° 07:05	6.67	24%	130.8°
2031-04-27 Sun	71	—	unknown	02:00–04:40 (good, 2.67 h)	71.1° 07:00	6.61	32%	137.1°
2031-04-28 Mon	71	—	unknown	01:55–04:35 (good, 2.67 h)	71.1° 06:55	6.55	42%	141.4°
2031-04-29 Tue	71	—	unknown	01:55–04:35 (good, 2.67 h)	71.1° 06:50	6.49	51%	142.8°
2031-04-30 Wed	73	—	unknown	01:50–04:35 (good, 2.75 h)	71.1° 06:50	6.43	61%	141.0°
2031-05-01 Thu	72	—	unknown	01:50–04:30 (good, 2.67 h)	71.1° 06:45	6.38	70%	136.1°
2031-05-02 Fri	72	—	unknown	01:45–04:30 (good, 2.75 h)	71.1° 06:40	6.32	79%	128.9°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2031-04-03&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.