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: 05-10 (73), 05-22 (72), 05-23 (71), 05-21 (70), 05-24 (69) — by astronomy; check the weather when the night is within four days.

2038-05-10astronomy score per night — click a bar for that night2038-06-08

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-05-10 Mon	73	—	unknown	22:25–02:30 (good, 4.08 h)	50.1° 22:35	5.85	37%	60.9°
2038-05-11 Tue	56	—	unknown	22:25–02:05 (good, 3.67 h)	50.1° 22:35	5.79	47%	47.6°
2038-05-12 Wed	39	—	unknown	22:30–02:50 (marginal, 4.33 h)	50.1° 22:30	5.73	58%	34.0°
2038-05-13 Thu	27	—	unknown	22:30–02:40 (marginal, 4.17 h)	50.1° 22:25	5.68	69%	19.9°
2038-05-14 Fri	20	—	unknown	22:30–02:25 (marginal, 3.92 h)	50.1° 22:20	5.63	79%	5.5°
2038-05-15 Sat	15	—	unknown	22:35–02:05 (marginal, 3.5 h)	50.1° 22:20	5.57	88%	9.3°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-05-10&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.