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: 05-24 (100), 05-25 (100), 05-26 (100), 05-27 (100), 05-22 (99) — by astronomy; check the weather when the night is within four days.

2042-05-01astronomy score per night — click a bar for that night2042-05-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-05-01 Thu	59	—	unknown	01:55–04:30 (good, 2.58 h)	71.1° 06:45	6.36	90%	112.9°
2042-05-02 Fri	54	—	unknown	01:55–04:30 (good, 2.58 h)	71.1° 06:40	6.3	95%	105.5°
2042-05-03 Sat	49	—	unknown	02:00–04:25 (good, 2.42 h)	71.1° 06:35	6.24	98%	97.6°
2042-05-04 Sun	44	—	unknown	02:20–04:25 (good, 2.08 h)	71.1° 06:30	6.18	100%	89.5°
2042-05-05 Mon	40	—	unknown	02:50–04:25 (good, 1.58 h)	71.1° 06:25	6.13	100%	81.2°
2042-05-06 Tue	37	—	unknown	03:10–04:20 (good, 1.17 h)	71.1° 06:25	6.07	97%	73.1°
2042-05-07 Wed	36	—	unknown	03:15–04:20 (good, 1.08 h)	71.1° 06:20	6.01	93%	65.4°
2042-05-08 Thu	37	—	unknown	03:05–04:20 (good, 1.25 h)	71.1° 06:15	5.96	87%	58.4°
2042-05-09 Fri	40	—	unknown	02:10–04:15 (good, 2.08 h)	71.1° 06:10	5.9	79%	52.6°
2042-05-10 Sat	57	—	unknown	01:05–04:15 (good, 3.17 h)	71.1° 06:05	5.84	70%	48.7°
2042-05-11 Sun	66	—	unknown	01:00–04:15 (good, 3.25 h)	71.1° 06:05	5.79	60%	47.3°
2042-05-12 Mon	74	—	unknown	01:00–04:10 (good, 3.17 h)	71.1° 06:00	5.73	49%	48.8°
2042-05-13 Tue	83	—	unknown	00:55–04:10 (good, 3.25 h)	71.1° 05:55	5.68	37%	53.2°
2042-05-14 Wed	87	—	unknown	00:50–04:10 (good, 3.33 h)	71.1° 05:50	5.62	27%	59.9°
2042-05-15 Thu	90	—	unknown	00:45–04:05 (good, 3.33 h)	71.1° 05:50	5.57	17%	68.2°
2042-05-16 Fri	92	—	unknown	00:40–04:05 (good, 3.42 h)	71.1° 05:45	5.52	9%	77.6°
2042-05-17 Sat	94	—	unknown	00:40–04:05 (good, 3.42 h)	71.1° 05:40	5.47	3%	87.5°
2042-05-18 Sun	94	—	unknown	00:35–04:00 (good, 3.42 h)	71.1° 05:35	5.41	0%	97.5°
2042-05-19 Mon	94	—	unknown	00:30–04:00 (good, 3.5 h)	71.1° 05:30	5.36	0%	107.1°
2042-05-20 Tue	96	—	unknown	00:25–04:00 (good, 3.58 h)	71.1° 05:30	5.31	3%	115.9°
2042-05-21 Wed	98	—	unknown	00:25–04:00 (good, 3.58 h)	71.1° 05:25	5.26	8%	123.3°
2042-05-22 Thu	99	—	unknown	00:20–03:55 (good, 3.58 h)	71.1° 05:20	5.22	15%	128.8°
2042-05-23 Fri	99	—	unknown	00:15–03:55 (good, 3.67 h)	71.1° 05:15	5.17	23%	132.0°
2042-05-24 Sat	100	—	unknown	00:15–03:55 (good, 3.67 h)	71.1° 05:10	5.12	32%	132.7°
2042-05-25 Sun	100	—	unknown	00:10–03:55 (good, 3.75 h)	71.1° 05:10	5.08	42%	130.9°
2042-05-26 Mon	100	—	unknown	00:10–03:50 (good, 3.67 h)	71.1° 05:05	5.03	52%	127.0°
2042-05-27 Tue	100	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 05:00	4.99	61%	121.6°
2042-05-28 Wed	99	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 04:55	4.95	70%	115.1°
2042-05-29 Thu	96	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 04:55	4.91	78%	107.8°
2042-05-30 Fri	80	—	unknown	00:10–03:45 (good, 3.58 h)	71.1° 04:50	4.87	86%	100.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-05-01&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.