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: 04-22 (93), 04-23 (93), 04-24 (93), 04-25 (93), 04-26 (93) — by astronomy; check the weather when the night is within four days.

2038-04-22astronomy score per night — click a bar for that night2038-05-21

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-04-22 Thu	93	—	unknown	21:55–02:50 (good, 4.92 h)	50.1° 23:50	6.88	83%	75.5°
2038-04-23 Fri	93	—	unknown	21:55–03:15 (good, 5.33 h)	50.1° 23:45	6.82	74%	89.5°
2038-04-24 Sat	93	—	unknown	22:00–03:20 (good, 5.33 h)	50.1° 23:40	6.77	64%	103.0°
2038-04-25 Sun	93	—	unknown	22:00–03:25 (good, 5.42 h)	50.1° 23:35	6.71	53%	116.1°
2038-04-26 Mon	93	—	unknown	22:00–03:25 (good, 5.42 h)	50.1° 23:30	6.65	43%	128.7°
2038-04-27 Tue	93	—	unknown	22:05–03:20 (good, 5.25 h)	50.1° 23:30	6.59	34%	141.1°
2038-04-28 Wed	93	—	unknown	22:05–03:15 (good, 5.17 h)	50.1° 23:25	6.53	25%	153.2°
2038-04-29 Thu	93	—	unknown	22:05–03:10 (good, 5.08 h)	50.1° 23:20	6.47	17%	165.2°
2038-04-30 Fri	93	—	unknown	22:10–03:10 (good, 5.0 h)	50.1° 23:15	6.42	11%	177.1°
2038-05-01 Sat	93	—	unknown	22:10–03:05 (good, 4.92 h)	50.1° 23:15	6.36	6%	171.1°
2038-05-02 Sun	93	—	unknown	22:10–03:00 (good, 4.83 h)	50.1° 23:10	6.3	2%	159.3°
2038-05-03 Mon	93	—	unknown	22:15–02:55 (good, 4.67 h)	50.1° 23:05	6.24	0%	147.5°
2038-05-04 Tue	93	—	unknown	22:15–02:55 (good, 4.67 h)	50.1° 23:00	6.19	0%	135.5°
2038-05-05 Wed	93	—	unknown	22:15–02:50 (good, 4.58 h)	50.1° 22:55	6.13	2%	123.5°
2038-05-06 Thu	93	—	unknown	22:20–02:45 (good, 4.42 h)	50.1° 22:55	6.07	6%	111.4°
2038-05-07 Fri	93	—	unknown	22:20–02:40 (good, 4.33 h)	50.1° 22:50	6.01	11%	99.1°
2038-05-08 Sat	90	—	unknown	22:20–02:35 (good, 4.25 h)	50.1° 22:45	5.96	18%	86.6°
2038-05-09 Sun	85	—	unknown	22:25–02:35 (good, 4.17 h)	50.1° 22:40	5.9	27%	73.9°
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°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-04-22&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.