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: 04-28 (92), 04-29 (89), 05-13 (89), 05-14 (89), 05-12 (87) — by astronomy; check the weather when the night is within four days.

2028-04-28astronomy score per night — click a bar for that night2028-05-27

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
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°
2028-05-02 Tue	54	—	unknown	22:50–02:35 (good, 3.75 h)	50.2° 23:05	6.28	59%	42.6°
2028-05-03 Wed	36	—	unknown	22:15–03:20 (marginal, 5.08 h)	50.2° 23:05	6.22	70%	28.9°
2028-05-04 Thu	28	—	unknown	22:15–03:10 (marginal, 4.92 h)	50.2° 23:00	6.16	80%	16.0°
2028-05-05 Fri	22	—	unknown	22:15–02:55 (marginal, 4.67 h)	50.2° 22:55	6.1	89%	9.6°
2028-05-06 Sat	18	—	unknown	22:20–02:40 (marginal, 4.33 h)	50.2° 22:50	6.05	95%	18.5°
2028-05-07 Sun	20	—	unknown	22:20–02:30 (marginal, 4.17 h)	50.2° 22:45	5.99	99%	31.6°
2028-05-08 Mon	31	—	unknown	22:20–02:40 (marginal, 4.33 h)	50.2° 22:45	5.93	100%	45.2°
2028-05-09 Tue	43	—	unknown	22:25–23:20 (good, 0.92 h)	50.2° 22:40	5.88	98%	58.8°
2028-05-10 Wed	75	—	unknown	22:25–01:05 (good, 2.67 h)	50.2° 22:35	5.82	95%	72.0°
2028-05-11 Thu	83	—	unknown	22:25–01:55 (good, 3.5 h)	50.2° 22:30	5.77	89%	85.0°
2028-05-12 Fri	87	—	unknown	22:30–02:05 (good, 3.58 h)	50.2° 22:25	5.71	82%	97.6°
2028-05-13 Sat	89	—	unknown	22:30–02:05 (good, 3.58 h)	50.2° 22:25	5.66	73%	109.9°
2028-05-14 Sun	89	—	unknown	22:30–02:05 (good, 3.58 h)	50.2° 22:20	5.6	64%	121.9°
2028-05-15 Mon	86	—	unknown	22:35–02:05 (good, 3.5 h)	50.2° 22:15	5.55	55%	133.6°
2028-05-16 Tue	85	—	unknown	22:35–02:05 (good, 3.5 h)	50.2° 22:10	5.5	46%	145.1°
2028-05-17 Wed	84	—	unknown	22:35–02:00 (good, 3.42 h)	50.2° 22:10	5.45	36%	156.2°
2028-05-18 Thu	81	—	unknown	22:40–01:55 (good, 3.25 h)	50.2° 22:05	5.39	27%	166.2°
2028-05-19 Fri	79	—	unknown	22:40–01:50 (good, 3.17 h)	50.2° 22:00	5.34	19%	170.2°
2028-05-20 Sat	77	—	unknown	22:40–01:50 (good, 3.17 h)	50.2° 21:55	5.29	12%	162.9°
2028-05-21 Sun	74	—	unknown	22:45–01:45 (good, 3.0 h)	50.2° 21:50	5.24	6%	151.8°
2028-05-22 Mon	73	—	unknown	22:45–01:40 (good, 2.92 h)	50.2° 21:50	5.2	2%	139.7°
2028-05-23 Tue	71	—	unknown	22:45–01:35 (good, 2.83 h)	50.2° 21:45	5.15	0%	127.0°
2028-05-24 Wed	69	—	unknown	22:45–01:30 (good, 2.75 h)	50.2° 21:40	5.1	0%	113.9°
2028-05-25 Thu	66	—	unknown	22:50–01:30 (good, 2.67 h)	50.2° 21:35	5.06	3%	100.6°
2028-05-26 Fri	63	—	unknown	22:50–01:25 (good, 2.58 h)	50.2° 21:30	5.01	8%	87.0°
2028-05-27 Sat	59	—	unknown	22:50–01:20 (good, 2.5 h)	50.2° 21:30	4.97	15%	73.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-04-28&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.