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: 12-01 (40), 12-14 (35), 12-02 (34), 12-15 (34), 12-11 (32) — by astronomy; check the weather when the night is within four days.

2038-12-01astronomy score per night — click a bar for that night2038-12-30

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-12-01 Wed	40	—	unknown	18:35–20:35 (good, 2.0 h)	71.1° 15:40	11.33	34%	47.5°
2038-12-02 Thu	34	—	unknown	18:35–20:25 (good, 1.83 h)	71.1° 15:35	11.35	44%	52.1°
2038-12-03 Fri	29	—	unknown	18:35–20:15 (good, 1.67 h)	71.1° 15:35	11.37	54%	58.3°
2038-12-04 Sat	26	—	unknown	18:35–19:35 (good, 1.0 h)	71.1° 15:30	11.38	64%	65.5°
2038-12-05 Sun	24	—	unknown	18:35–19:15 (good, 0.67 h)	71.1° 15:25	11.39	72%	73.4°
2038-12-06 Mon	24	—	unknown	18:35–19:15 (good, 0.67 h)	71.1° 15:20	11.41	80%	81.5°
2038-12-07 Tue	24	—	unknown	18:35–19:25 (good, 0.83 h)	71.1° 15:20	11.42	87%	89.8°
2038-12-08 Wed	26	—	unknown	18:35–19:50 (good, 1.25 h)	71.1° 15:15	11.43	93%	98.1°
2038-12-09 Thu	28	—	unknown	18:35–19:55 (good, 1.33 h)	71.1° 15:10	11.44	97%	106.3°
2038-12-10 Fri	30	—	unknown	18:35–19:55 (good, 1.33 h)	71.1° 15:05	11.45	99%	114.1°
2038-12-11 Sat	32	—	unknown	18:35–19:55 (good, 1.33 h)	71.1° 15:00	11.46	100%	121.3°
2038-12-12 Sun	31	—	unknown	18:35–19:55 (good, 1.33 h)	71.1° 15:00	11.47	99%	127.4°
2038-12-13 Mon	32	—	unknown	18:35–19:50 (good, 1.25 h)	71.1° 14:55	11.48	96%	132.0°
2038-12-14 Tue	35	—	unknown	18:35–19:50 (good, 1.25 h)	71.1° 14:50	11.49	90%	134.5°
2038-12-15 Wed	34	—	unknown	18:35–19:55 (good, 1.33 h)	71.1° 14:45	11.49	84%	134.3°
2038-12-16 Thu	32	—	unknown	18:35–19:50 (good, 1.25 h)	71.1° 14:40	11.5	75%	131.4°
2038-12-17 Fri	31	—	unknown	18:35–19:45 (good, 1.17 h)	71.1° 14:40	11.5	66%	126.1°
2038-12-18 Sat	30	—	unknown	18:35–19:40 (good, 1.08 h)	71.1° 14:35	11.5	55%	118.9°
2038-12-19 Sun	29	—	unknown	18:35–19:35 (good, 1.0 h)	71.1° 14:30	11.51	44%	110.4°
2038-12-20 Mon	27	—	unknown	18:35–19:35 (good, 1.0 h)	71.1° 14:25	11.51	33%	100.9°
2038-12-21 Tue	25	—	unknown	18:35–19:30 (good, 0.92 h)	71.1° 14:25	11.51	23%	90.9°
2038-12-22 Wed	23	—	unknown	18:35–19:25 (good, 0.83 h)	71.1° 14:20	11.51	14%	80.6°
2038-12-23 Thu	22	—	unknown	18:40–19:20 (good, 0.67 h)	71.1° 14:15	11.51	6%	70.5°
2038-12-24 Fri	20	—	unknown	18:40–19:15 (good, 0.58 h)	71.1° 14:10	11.5	2%	61.2°
2038-12-25 Sat	19	—	unknown	18:40–19:15 (good, 0.58 h)	71.1° 14:05	11.5	0%	53.3°
2038-12-26 Sun	18	—	unknown	18:40–19:10 (good, 0.5 h)	71.1° 14:05	11.5	1%	47.8°
2038-12-27 Mon	16	—	unknown	18:40–19:05 (good, 0.42 h)	71.1° 14:00	11.49	5%	45.3°
2038-12-28 Tue	13	—	unknown	18:40–19:00 (good, 0.33 h)	71.1° 13:55	11.48	11%	46.3°
2038-12-29 Wed	11	—	unknown	18:40–18:50 (good, 0.17 h)	71.1° 13:50	11.48	18%	50.1°
2038-12-30 Thu	8	—	unknown	18:10–19:20 (marginal, 1.17 h)	71.1° 13:45	11.47	27%	56.0°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-12-01&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.