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: 02-10 (6), 02-08 (5), 02-09 (5), 02-07 (4), 02-04 (3) — by astronomy; check the weather when the night is within four days.

2038-01-12astronomy score per night — click a bar for that night2038-02-10

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-01-12 Tue	0	—	unknown	—	71.1° 12:55	11.28	44%	77.4°
2038-01-13 Wed	0	—	unknown	—	71.1° 12:50	11.27	54%	85.8°
2038-01-14 Thu	0	—	unknown	—	71.1° 12:45	11.24	63%	94.5°
2038-01-15 Fri	0	—	unknown	—	71.1° 12:45	11.22	72%	103.2°
2038-01-16 Sat	0	—	unknown	—	71.1° 12:40	11.2	81%	111.7°
2038-01-17 Sun	0	—	unknown	—	71.1° 12:35	11.18	88%	119.9°
2038-01-18 Mon	0	—	unknown	—	71.1° 12:30	11.15	94%	127.2°
2038-01-19 Tue	0	—	unknown	—	71.1° 12:30	11.13	98%	132.9°
2038-01-20 Wed	0	—	unknown	—	71.1° 12:25	11.11	100%	136.0°
2038-01-21 Thu	0	—	unknown	—	71.1° 12:20	11.08	99%	135.7°
2038-01-22 Fri	0	—	unknown	—	71.1° 12:15	11.05	96%	131.9°
2038-01-23 Sat	0	—	unknown	—	71.1° 12:10	11.03	90%	125.3°
2038-01-24 Sun	0	—	unknown	—	71.1° 12:10	11.0	82%	116.8°
2038-01-25 Mon	0	—	unknown	—	71.1° 12:00	10.97	72%	107.2°
2038-01-26 Tue	0	—	unknown	—	71.1° 12:00	10.94	61%	97.1°
2038-01-27 Wed	0	—	unknown	—	71.1° 11:50	10.91	50%	86.9°
2038-01-28 Thu	1	—	unknown	—	71.1° 11:50	10.88	39%	77.0°
2038-01-29 Fri	1	—	unknown	—	71.1° 11:45	10.85	28%	67.5°
2038-01-30 Sat	1	—	unknown	—	71.1° 11:40	10.82	19%	59.0°
2038-01-31 Sun	1	—	unknown	—	71.1° 11:35	10.79	11%	51.8°
2038-02-01 Mon	1	—	unknown	—	71.1° 11:35	10.75	6%	46.6°
2038-02-02 Tue	1	—	unknown	06:25–06:30 (marginal, 0.08 h)	71.1° 11:30	10.72	2%	43.9°
2038-02-03 Wed	2	—	unknown	05:55–06:00 (marginal, 0.08 h)	71.1° 11:25	10.69	0%	44.2°
2038-02-04 Thu	3	—	unknown	06:20–06:30 (marginal, 0.17 h)	71.1° 11:20	10.65	0%	47.3°
2038-02-05 Fri	3	—	unknown	06:15–06:30 (marginal, 0.25 h)	71.1° 11:15	10.62	3%	52.4°
2038-02-06 Sat	3	—	unknown	06:10–06:25 (marginal, 0.25 h)	71.1° 11:15	10.58	7%	59.1°
2038-02-07 Sun	4	—	unknown	05:40–05:55 (marginal, 0.25 h)	71.1° 11:10	10.55	13%	66.6°
2038-02-08 Mon	5	—	unknown	05:35–05:55 (marginal, 0.33 h)	71.1° 11:05	10.51	20%	74.6°
2038-02-09 Tue	5	—	unknown	06:00–06:25 (marginal, 0.42 h)	71.1° 11:00	10.47	28%	83.0°
2038-02-10 Wed	6	—	unknown	05:55–06:25 (marginal, 0.5 h)	71.1° 10:55	10.44	36%	91.5°

Download: CSV · JSON

💡 API

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