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: 02-25 (19), 02-23 (18), 02-24 (17), 02-22 (16), 02-20 (15) — by astronomy; check the weather when the night is within four days.

2037-01-27astronomy score per night — click a bar for that night2037-02-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2037-01-27 Tue	1	—	unknown	—	71.1° 11:50	10.9	82%	121.4°
2037-01-28 Wed	1	—	unknown	—	71.1° 11:45	10.87	90%	129.4°
2037-01-29 Thu	1	—	unknown	—	71.1° 11:45	10.84	96%	135.4°
2037-01-30 Fri	1	—	unknown	—	71.1° 11:40	10.81	99%	137.9°
2037-01-31 Sat	1	—	unknown	—	71.1° 11:35	10.78	100%	136.2°
2037-02-01 Sun	1	—	unknown	—	71.1° 11:30	10.75	97%	130.7°
2037-02-02 Mon	1	—	unknown	—	71.1° 11:30	10.71	92%	122.4°
2037-02-03 Tue	2	—	unknown	05:55–06:00 (marginal, 0.08 h)	71.1° 11:25	10.68	84%	112.7°
2037-02-04 Wed	2	—	unknown	05:50–05:55 (marginal, 0.08 h)	71.1° 11:20	10.64	74%	102.4°
2037-02-05 Thu	2	—	unknown	05:45–05:55 (marginal, 0.17 h)	71.1° 11:15	10.61	64%	92.1°
2037-02-06 Fri	2	—	unknown	05:45–05:55 (marginal, 0.17 h)	71.1° 11:10	10.57	53%	82.0°
2037-02-07 Sat	3	—	unknown	05:40–05:55 (marginal, 0.25 h)	71.1° 11:10	10.54	43%	72.4°
2037-02-08 Sun	3	—	unknown	05:35–05:50 (marginal, 0.25 h)	71.1° 11:05	10.5	33%	63.5°
2037-02-09 Mon	4	—	unknown	05:30–05:50 (marginal, 0.33 h)	71.1° 11:00	10.46	24%	55.6°
2037-02-10 Tue	5	—	unknown	05:30–05:50 (marginal, 0.33 h)	71.1° 10:55	10.43	16%	49.1°
2037-02-11 Wed	6	—	unknown	05:25–05:50 (marginal, 0.42 h)	71.1° 10:50	10.39	9%	44.4°
2037-02-12 Thu	8	—	unknown	05:45–05:50 (good, 0.08 h)	71.1° 10:50	10.35	4%	42.2°
2037-02-13 Fri	8	—	unknown	05:15–06:20 (marginal, 1.08 h)	71.1° 10:45	10.31	1%	42.6°
2037-02-14 Sat	9	—	unknown	05:40–05:45 (good, 0.08 h)	71.1° 10:40	10.27	0%	45.7°
2037-02-15 Sun	9	—	unknown	05:35–05:45 (good, 0.17 h)	71.1° 10:35	10.23	0%	50.8°
2037-02-16 Mon	11	—	unknown	05:30–05:45 (good, 0.25 h)	71.1° 10:35	10.19	3%	57.4°
2037-02-17 Tue	11	—	unknown	05:25–05:40 (good, 0.25 h)	71.1° 10:30	10.15	7%	65.0°
2037-02-18 Wed	13	—	unknown	05:25–05:40 (good, 0.25 h)	71.1° 10:25	10.11	12%	73.3°
2037-02-19 Thu	14	—	unknown	05:20–05:40 (good, 0.33 h)	71.1° 10:20	10.07	19%	82.0°
2037-02-20 Fri	15	—	unknown	05:15–05:40 (good, 0.42 h)	71.1° 10:15	10.03	27%	91.0°
2037-02-21 Sat	15	—	unknown	05:10–05:35 (good, 0.42 h)	71.1° 10:15	9.98	36%	100.2°
2037-02-22 Sun	16	—	unknown	05:10–05:35 (good, 0.42 h)	71.1° 10:10	9.94	46%	109.3°
2037-02-23 Mon	18	—	unknown	05:05–05:35 (good, 0.5 h)	71.1° 10:05	9.9	57%	118.2°
2037-02-24 Tue	17	—	unknown	05:00–05:30 (good, 0.5 h)	71.1° 10:00	9.86	68%	126.4°
2037-02-25 Wed	19	—	unknown	04:55–05:30 (good, 0.58 h)	71.1° 09:55	9.81	78%	133.1°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2037-01-27&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.