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 3C 273: 05-22 (72), 05-23 (71), 05-21 (70), 05-24 (69), 05-25 (67) — by astronomy; check the weather when the night is within four days.

2038-05-16astronomy score per night — click a bar for that night2038-06-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-05-16 Sun	13	—	unknown	22:35–01:50 (marginal, 3.25 h)	50.1° 22:15	5.52	95%	24.2°
2038-05-17 Mon	17	—	unknown	22:35–01:50 (marginal, 3.25 h)	50.1° 22:10	5.47	99%	39.3°
2038-05-18 Tue	27	—	unknown	22:35–02:00 (marginal, 3.42 h)	50.1° 22:05	5.42	100%	54.3°
2038-05-19 Wed	37	—	unknown	22:40–23:45 (good, 1.08 h)	50.1° 22:00	5.37	98%	69.2°
2038-05-20 Thu	63	—	unknown	22:40–01:15 (good, 2.58 h)	50.1° 22:00	5.32	94%	83.7°
2038-05-21 Fri	70	—	unknown	22:40–01:30 (good, 2.83 h)	50.1° 21:55	5.27	87%	97.8°
2038-05-22 Sat	72	—	unknown	22:45–01:35 (good, 2.83 h)	50.1° 21:50	5.22	78%	111.4°
2038-05-23 Sun	71	—	unknown	22:45–01:35 (good, 2.83 h)	50.1° 21:45	5.17	69%	124.6°
2038-05-24 Mon	69	—	unknown	22:45–01:35 (good, 2.83 h)	50.1° 21:40	5.12	59%	137.3°
2038-05-25 Tue	67	—	unknown	22:50–01:30 (good, 2.67 h)	50.1° 21:40	5.08	49%	149.7°
2038-05-26 Wed	66	—	unknown	22:50–01:25 (good, 2.58 h)	50.1° 21:35	5.03	40%	161.9°
2038-05-27 Thu	64	—	unknown	22:50–01:20 (good, 2.5 h)	50.1° 21:30	4.99	31%	173.8°
2038-05-28 Fri	62	—	unknown	22:50–01:20 (good, 2.5 h)	50.1° 21:25	4.95	22%	174.3°
2038-05-29 Sat	60	—	unknown	22:55–01:15 (good, 2.33 h)	50.1° 21:25	4.91	15%	162.5°
2038-05-30 Sun	58	—	unknown	22:55–01:10 (good, 2.25 h)	50.1° 21:20	4.87	9%	150.6°
2038-05-31 Mon	56	—	unknown	22:55–01:05 (good, 2.17 h)	50.1° 21:15	4.83	4%	138.7°
2038-06-01 Tue	53	—	unknown	23:00–01:05 (good, 2.08 h)	50.1° 21:10	4.79	1%	126.7°
2038-06-02 Wed	51	—	unknown	23:00–01:00 (good, 2.0 h)	50.1° 21:05	4.76	0%	114.5°
2038-06-03 Thu	50	—	unknown	23:00–00:55 (good, 1.92 h)	50.1° 21:05	4.72	1%	102.1°
2038-06-04 Fri	48	—	unknown	23:00–00:50 (good, 1.83 h)	50.1° 21:00	4.69	4%	89.6°
2038-06-05 Sat	46	—	unknown	23:00–00:45 (good, 1.75 h)	50.1° 20:55	4.66	8%	76.8°
2038-06-06 Sun	41	—	unknown	23:05–00:45 (good, 1.67 h)	50.1° 20:50	4.63	15%	63.9°
2038-06-07 Mon	35	—	unknown	23:05–00:30 (good, 1.42 h)	50.1° 20:45	4.6	23%	50.7°
2038-06-08 Tue	28	—	unknown	23:05–00:20 (good, 1.25 h)	50.1° 20:45	4.58	33%	37.2°
2038-06-09 Wed	22	—	unknown	23:05–00:05 (good, 1.0 h)	50.1° 20:40	4.55	44%	23.5°
2038-06-10 Thu	17	—	unknown	23:05–00:55 (marginal, 1.83 h)	50.1° 20:35	4.53	55%	9.6°
2038-06-11 Fri	12	—	unknown	23:10–00:40 (marginal, 1.5 h)	50.1° 20:30	4.51	66%	4.6°
2038-06-12 Sat	9	—	unknown	23:10–00:25 (marginal, 1.25 h)	50.1° 20:30	4.49	77%	19.1°
2038-06-13 Sun	7	—	unknown	23:10–00:15 (marginal, 1.08 h)	50.1° 20:25	4.48	86%	33.7°
2038-06-14 Mon	8	—	unknown	23:10–00:15 (marginal, 1.08 h)	50.1° 20:20	4.46	93%	48.4°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-05-16&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.