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 Seven Sisters: 04-03 (3), 04-04 (3), 04-05 (3), 04-06 (3), 04-07 (2) — by astronomy; check the weather when the night is within four days.

2028-04-03astronomy score per night — click a bar for that night2028-05-02

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2028-04-03 Mon	3	—	unknown	21:30–21:50 (marginal, 0.33 h)	72.5° 16:20	7.94	63%	59.6°
2028-04-04 Tue	3	—	unknown	21:30–21:45 (marginal, 0.25 h)	72.5° 16:15	7.89	73%	73.9°
2028-04-05 Wed	3	—	unknown	21:30–21:45 (marginal, 0.25 h)	72.5° 16:10	7.83	83%	88.5°
2028-04-06 Thu	3	—	unknown	21:30–21:45 (marginal, 0.25 h)	72.5° 16:10	7.78	91%	103.3°
2028-04-07 Fri	2	—	unknown	21:35–21:40 (marginal, 0.08 h)	72.5° 16:05	7.72	97%	118.2°
2028-04-08 Sat	2	—	unknown	21:35–21:40 (marginal, 0.08 h)	72.5° 16:00	7.66	100%	133.0°
2028-04-09 Sun	1	—	unknown	—	72.5° 15:55	7.61	100%	147.8°
2028-04-10 Mon	1	—	unknown	21:00–21:05 (marginal, 0.08 h)	72.5° 15:50	7.55	97%	162.2°
2028-04-11 Tue	1	—	unknown	—	72.5° 15:50	7.49	92%	176.2°
2028-04-12 Wed	1	—	unknown	—	72.5° 15:45	7.44	85%	170.1°
2028-04-13 Thu	1	—	unknown	—	72.5° 15:40	7.38	76%	156.9°
2028-04-14 Fri	0	—	unknown	—	72.5° 15:35	7.32	67%	144.2°
2028-04-15 Sat	0	—	unknown	—	72.5° 15:30	7.26	57%	131.7°
2028-04-16 Sun	0	—	unknown	—	72.5° 15:30	7.21	48%	119.6°
2028-04-17 Mon	0	—	unknown	—	72.5° 15:25	7.15	38%	107.6°
2028-04-18 Tue	0	—	unknown	—	72.5° 15:20	7.09	29%	95.8°
2028-04-19 Wed	0	—	unknown	—	72.5° 15:15	7.03	21%	84.0°
2028-04-20 Thu	0	—	unknown	—	72.5° 15:15	6.97	14%	72.1°
2028-04-21 Fri	0	—	unknown	—	72.5° 15:10	6.92	8%	60.1°
2028-04-22 Sat	0	—	unknown	—	72.5° 15:05	6.86	4%	48.0°
2028-04-23 Sun	0	—	unknown	—	72.5° 15:00	6.8	1%	35.7°
2028-04-24 Mon	0	—	unknown	—	72.5° 14:55	6.74	0%	23.2°
2028-04-25 Tue	0	—	unknown	—	72.5° 14:55	6.68	1%	10.5°
2028-04-26 Wed	0	—	unknown	—	72.5° 14:50	6.62	5%	2.4°
2028-04-27 Thu	0	—	unknown	—	72.5° 14:45	6.57	10%	15.6°
2028-04-28 Fri	0	—	unknown	—	72.5° 14:40	6.51	18%	28.9°
2028-04-29 Sat	0	—	unknown	—	72.5° 14:35	6.45	27%	42.5°
2028-04-30 Sun	0	—	unknown	—	72.5° 14:35	6.39	37%	56.2°
2028-05-01 Mon	0	—	unknown	—	72.5° 14:30	6.33	48%	70.2°
2028-05-02 Tue	0	—	unknown	—	72.5° 14:25	6.28	59%	84.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2028-04-03&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.