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: 05-30 (99), 05-29 (96), 05-28 (89), 05-14 (87), 05-11 (86) — by astronomy; check the weather when the night is within four days.

2027-05-01astronomy score per night — click a bar for that night2027-05-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-05-01 Sat	71	—	unknown	01:40–04:30 (good, 2.83 h)	71.1° 06:45	6.38	22%	51.6°
2027-05-02 Sun	76	—	unknown	01:40–04:30 (good, 2.83 h)	71.1° 06:40	6.32	14%	58.6°
2027-05-03 Mon	78	—	unknown	01:35–04:30 (good, 2.92 h)	71.1° 06:35	6.26	8%	67.0°
2027-05-04 Tue	77	—	unknown	01:30–04:25 (good, 2.92 h)	71.1° 06:30	6.2	3%	76.4°
2027-05-05 Wed	79	—	unknown	01:25–04:25 (good, 3.0 h)	71.1° 06:30	6.15	0%	86.3°
2027-05-06 Thu	81	—	unknown	01:25–04:25 (good, 3.0 h)	71.1° 06:25	6.09	0%	96.6°
2027-05-07 Fri	82	—	unknown	01:20–04:20 (good, 3.0 h)	71.1° 06:20	6.03	3%	106.9°
2027-05-08 Sat	82	—	unknown	01:15–04:20 (good, 3.08 h)	71.1° 06:15	5.98	8%	116.8°
2027-05-09 Sun	83	—	unknown	01:10–04:15 (good, 3.08 h)	71.1° 06:10	5.92	16%	125.6°
2027-05-10 Mon	85	—	unknown	01:05–04:15 (good, 3.17 h)	71.1° 06:10	5.86	25%	132.5°
2027-05-11 Tue	86	—	unknown	01:05–04:15 (good, 3.17 h)	71.1° 06:05	5.81	36%	136.7°
2027-05-12 Wed	86	—	unknown	01:05–04:10 (good, 3.08 h)	71.1° 06:00	5.75	47%	137.2°
2027-05-13 Thu	86	—	unknown	01:00–04:10 (good, 3.17 h)	71.1° 05:55	5.7	58%	134.1°
2027-05-14 Fri	87	—	unknown	01:00–04:10 (good, 3.17 h)	71.1° 05:50	5.64	69%	128.2°
2027-05-15 Sat	85	—	unknown	00:55–04:05 (good, 3.17 h)	71.1° 05:50	5.59	79%	120.4°
2027-05-16 Sun	83	—	unknown	00:55–04:05 (good, 3.17 h)	71.1° 05:45	5.54	87%	111.6°
2027-05-17 Mon	68	—	unknown	01:00–04:05 (good, 3.08 h)	71.1° 05:40	5.48	93%	102.2°
2027-05-18 Tue	60	—	unknown	01:00–04:05 (good, 3.08 h)	71.1° 05:35	5.43	97%	92.7°
2027-05-19 Wed	51	—	unknown	01:35–04:00 (good, 2.42 h)	71.1° 05:35	5.38	100%	83.2°
2027-05-20 Thu	45	—	unknown	02:10–04:00 (good, 1.83 h)	71.1° 05:30	5.33	100%	74.1°
2027-05-21 Fri	41	—	unknown	02:40–04:00 (good, 1.33 h)	71.1° 05:25	5.28	98%	65.5°
2027-05-22 Sat	38	—	unknown	03:05–03:55 (good, 0.83 h)	71.1° 05:20	5.23	94%	57.7°
2027-05-23 Sun	39	—	unknown	03:10–03:55 (good, 0.75 h)	71.1° 05:15	5.19	89%	51.1°
2027-05-24 Mon	49	—	unknown	02:20–03:55 (good, 1.58 h)	71.1° 05:15	5.14	82%	46.0°
2027-05-25 Tue	63	—	unknown	00:10–03:55 (good, 3.75 h)	71.1° 05:10	5.09	74%	43.0°
2027-05-26 Wed	71	—	unknown	00:05–03:50 (good, 3.75 h)	71.1° 05:05	5.05	66%	42.6°
2027-05-27 Thu	80	—	unknown	00:00–03:50 (good, 3.83 h)	71.1° 05:00	5.0	56%	44.8°
2027-05-28 Fri	89	—	unknown	23:55–03:50 (good, 3.92 h)	71.1° 04:55	4.96	47%	49.3°
2027-05-29 Sat	96	—	unknown	23:50–03:50 (good, 4.0 h)	71.1° 04:55	4.92	37%	55.7°
2027-05-30 Sun	99	—	unknown	23:50–03:45 (good, 3.92 h)	71.1° 04:50	4.88	27%	63.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-05-01&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.