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: 05-14 (89), 05-17 (89), 05-13 (88), 05-15 (88), 05-16 (88) — by astronomy; check the weather when the night is within four days.

2043-04-20astronomy score per night — click a bar for that night2043-05-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2043-04-20 Mon	52	—	unknown	02:35–04:50 (good, 2.25 h)	71.1° 07:25	7.01	90%	120.6°
2043-04-21 Tue	50	—	unknown	02:35–04:50 (good, 2.25 h)	71.1° 07:25	6.95	95%	113.6°
2043-04-22 Wed	46	—	unknown	02:35–04:50 (good, 2.25 h)	71.1° 07:20	6.89	98%	106.0°
2043-04-23 Thu	41	—	unknown	02:40–04:45 (good, 2.08 h)	71.1° 07:15	6.84	100%	98.1°
2043-04-24 Fri	38	—	unknown	02:55–04:45 (good, 1.83 h)	71.1° 07:10	6.78	100%	89.9°
2043-04-25 Sat	35	—	unknown	03:15–04:45 (good, 1.5 h)	71.1° 07:05	6.72	98%	81.9°
2043-04-26 Sun	33	—	unknown	03:30–04:40 (good, 1.17 h)	71.1° 07:05	6.66	94%	73.9°
2043-04-27 Mon	33	—	unknown	03:30–04:40 (good, 1.17 h)	71.1° 07:00	6.6	88%	66.4°
2043-04-28 Tue	34	—	unknown	03:10–04:35 (good, 1.42 h)	71.1° 06:55	6.54	82%	59.5°
2043-04-29 Wed	37	—	unknown	02:20–04:35 (good, 2.25 h)	71.1° 06:50	6.49	74%	53.6°
2043-04-30 Thu	50	—	unknown	01:45–04:35 (good, 2.83 h)	71.1° 06:50	6.43	64%	49.2°
2043-05-01 Fri	57	—	unknown	01:40–04:30 (good, 2.83 h)	71.1° 06:45	6.37	55%	46.9°
2043-05-02 Sat	65	—	unknown	01:40–04:30 (good, 2.83 h)	71.1° 06:40	6.31	44%	47.1°
2043-05-03 Sun	72	—	unknown	01:35–04:30 (good, 2.92 h)	71.1° 06:35	6.25	34%	50.1°
2043-05-04 Mon	76	—	unknown	01:30–04:25 (good, 2.92 h)	71.1° 06:30	6.2	24%	55.6°
2043-05-05 Tue	79	—	unknown	01:25–04:25 (good, 3.0 h)	71.1° 06:30	6.14	15%	63.2°
2043-05-06 Wed	79	—	unknown	01:25–04:20 (good, 2.92 h)	71.1° 06:25	6.08	7%	72.2°
2043-05-07 Thu	82	—	unknown	01:20–04:20 (good, 3.0 h)	71.1° 06:20	6.03	2%	82.2°
2043-05-08 Fri	82	—	unknown	01:15–04:20 (good, 3.08 h)	71.1° 06:15	5.97	0%	92.7°
2043-05-09 Sat	83	—	unknown	01:10–04:15 (good, 3.08 h)	71.1° 06:10	5.91	1%	103.0°
2043-05-10 Sun	85	—	unknown	01:05–04:15 (good, 3.17 h)	71.1° 06:10	5.86	5%	112.8°
2043-05-11 Mon	86	—	unknown	01:05–04:15 (good, 3.17 h)	71.1° 06:05	5.8	12%	121.3°
2043-05-12 Tue	87	—	unknown	01:00–04:10 (good, 3.17 h)	71.1° 06:00	5.75	20%	128.0°
2043-05-13 Wed	88	—	unknown	00:55–04:10 (good, 3.25 h)	71.1° 05:55	5.69	30%	132.2°
2043-05-14 Thu	89	—	unknown	00:55–04:10 (good, 3.25 h)	71.1° 05:55	5.64	40%	133.5°
2043-05-15 Fri	88	—	unknown	00:50–04:05 (good, 3.25 h)	71.1° 05:50	5.58	50%	131.9°
2043-05-16 Sat	88	—	unknown	00:50–04:05 (good, 3.25 h)	71.1° 05:45	5.53	61%	127.9°
2043-05-17 Sun	89	—	unknown	00:45–04:05 (good, 3.33 h)	71.1° 05:40	5.48	70%	122.3°
2043-05-18 Mon	87	—	unknown	00:45–04:05 (good, 3.33 h)	71.1° 05:35	5.43	79%	115.5°
2043-05-19 Tue	74	—	unknown	00:45–04:00 (good, 3.25 h)	71.1° 05:35	5.38	86%	108.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2043-04-20&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.