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: 04-12 (93), 04-13 (93), 04-14 (93), 04-15 (93), 04-16 (93) — by astronomy; check the weather when the night is within four days.

2028-04-02astronomy score per night — click a bar for that night2028-05-01

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-04-02 Sun	87	—	unknown	21:40–04:55 (good, 7.25 h)	50.2° 01:05	8.0	51%	80.5°
2028-04-03 Mon	83	—	unknown	22:45–04:55 (good, 6.17 h)	50.2° 01:00	7.94	63%	66.7°
2028-04-04 Tue	75	—	unknown	01:35–04:20 (good, 2.75 h)	50.2° 00:55	7.89	73%	52.7°
2028-04-05 Wed	46	—	unknown	21:30–05:15 (marginal, 7.75 h)	50.2° 00:55	7.83	83%	38.5°
2028-04-06 Thu	31	—	unknown	22:10–04:55 (marginal, 6.75 h)	50.2° 00:50	7.78	91%	24.5°
2028-04-07 Fri	26	—	unknown	21:35–04:40 (marginal, 7.08 h)	50.2° 00:45	7.72	97%	12.2°
2028-04-08 Sat	24	—	unknown	21:35–04:30 (marginal, 6.92 h)	50.2° 00:40	7.66	100%	11.7°
2028-04-09 Sun	31	—	unknown	21:35–04:20 (marginal, 6.75 h)	50.2° 00:35	7.61	100%	23.6°
2028-04-10 Mon	73	—	unknown	21:40–21:45 (good, 0.08 h)	50.2° 00:35	7.55	97%	37.3°
2028-04-11 Tue	90	—	unknown	21:40–00:25 (good, 2.75 h)	50.2° 00:30	7.49	92%	50.9°
2028-04-12 Wed	93	—	unknown	21:40–02:45 (good, 5.08 h)	50.2° 00:25	7.44	85%	64.3°
2028-04-13 Thu	93	—	unknown	21:40–03:45 (good, 6.08 h)	50.2° 00:20	7.38	76%	77.3°
2028-04-14 Fri	93	—	unknown	21:45–03:55 (good, 6.17 h)	50.2° 00:15	7.32	67%	89.9°
2028-04-15 Sat	93	—	unknown	21:45–03:55 (good, 6.17 h)	50.2° 00:15	7.26	57%	102.1°
2028-04-16 Sun	93	—	unknown	21:45–03:55 (good, 6.17 h)	50.2° 00:10	7.21	48%	114.1°
2028-04-17 Mon	93	—	unknown	21:50–03:55 (good, 6.08 h)	50.2° 00:05	7.15	38%	125.8°
2028-04-18 Tue	93	—	unknown	21:50–03:55 (good, 6.08 h)	50.2° 00:00	7.09	29%	137.4°
2028-04-19 Wed	93	—	unknown	21:50–03:50 (good, 6.0 h)	50.2° 00:00	7.03	21%	148.7°
2028-04-20 Thu	93	—	unknown	21:55–03:45 (good, 5.83 h)	50.2° 23:55	6.97	14%	159.7°
2028-04-21 Fri	93	—	unknown	21:55–03:40 (good, 5.75 h)	50.2° 23:50	6.92	8%	168.8°
2028-04-22 Sat	93	—	unknown	21:55–03:40 (good, 5.75 h)	50.2° 23:45	6.86	4%	168.9°
2028-04-23 Sun	93	—	unknown	22:00–03:35 (good, 5.58 h)	50.2° 23:40	6.8	1%	159.5°
2028-04-24 Mon	93	—	unknown	22:00–03:30 (good, 5.5 h)	50.2° 23:40	6.74	0%	148.0°
2028-04-25 Tue	93	—	unknown	22:00–03:25 (good, 5.42 h)	50.2° 23:35	6.68	1%	135.7°
2028-04-26 Wed	93	—	unknown	22:00–03:20 (good, 5.33 h)	50.2° 23:30	6.62	5%	123.1°
2028-04-27 Thu	93	—	unknown	22:05–03:20 (good, 5.25 h)	50.2° 23:25	6.57	10%	110.1°
2028-04-28 Fri	92	—	unknown	22:05–03:15 (good, 5.17 h)	50.2° 23:20	6.51	18%	97.0°
2028-04-29 Sat	89	—	unknown	22:05–03:10 (good, 5.08 h)	50.2° 23:20	6.45	27%	83.6°
2028-04-30 Sun	84	—	unknown	22:10–03:05 (good, 4.92 h)	50.2° 23:15	6.39	37%	70.0°
2028-05-01 Mon	81	—	unknown	22:10–03:05 (good, 4.92 h)	50.2° 23:10	6.33	48%	56.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-04-02&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.