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 Great Orion Nebula: 01-27 (89), 01-28 (89), 01-29 (89), 01-30 (89), 01-31 (89) — by astronomy; check the weather when the night is within four days.

2030-01-27astronomy score per night — click a bar for that night2030-02-25

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2030-01-27 Sun	89	—	unknown	19:10–00:50 (good, 5.67 h)	42.9° 21:30	10.91	37%	137.8°
2030-01-28 Mon	89	—	unknown	19:10–00:45 (good, 5.58 h)	42.9° 21:25	10.88	26%	146.4°
2030-01-29 Tue	89	—	unknown	19:10–00:40 (good, 5.5 h)	42.9° 21:20	10.85	17%	151.1°
2030-01-30 Wed	89	—	unknown	19:10–00:35 (good, 5.42 h)	42.9° 21:20	10.82	9%	149.7°
2030-01-31 Thu	89	—	unknown	19:15–00:35 (good, 5.33 h)	42.9° 21:15	10.79	4%	143.1°
2030-02-01 Fri	89	—	unknown	19:15–00:30 (good, 5.25 h)	42.9° 21:10	10.76	1%	133.6°
2030-02-02 Sat	89	—	unknown	19:15–00:25 (good, 5.17 h)	42.9° 21:05	10.72	0%	122.9°
2030-02-03 Sun	89	—	unknown	19:15–00:20 (good, 5.08 h)	42.9° 21:00	10.69	2%	111.6°
2030-02-04 Mon	89	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 21:00	10.65	6%	100.3°
2030-02-05 Tue	89	—	unknown	19:20–00:15 (good, 4.92 h)	42.9° 20:55	10.62	12%	89.2°
2030-02-06 Wed	87	—	unknown	19:20–00:10 (good, 4.83 h)	42.9° 20:50	10.58	19%	78.3°
2030-02-07 Thu	83	—	unknown	19:20–00:05 (good, 4.75 h)	42.9° 20:45	10.55	27%	67.8°
2030-02-08 Fri	71	—	unknown	19:20–23:50 (good, 4.5 h)	42.9° 20:40	10.51	36%	57.7°
2030-02-09 Sat	56	—	unknown	19:25–23:35 (good, 4.17 h)	42.9° 20:40	10.48	45%	48.2°
2030-02-10 Sun	42	—	unknown	19:25–00:25 (marginal, 5.0 h)	42.9° 20:35	10.44	54%	39.7°
2030-02-11 Mon	29	—	unknown	19:25–00:10 (marginal, 4.75 h)	42.9° 20:30	10.4	64%	32.9°
2030-02-12 Tue	19	—	unknown	19:25–23:50 (marginal, 4.42 h)	42.9° 20:25	10.36	72%	29.0°
2030-02-13 Wed	14	—	unknown	19:30–23:20 (marginal, 3.83 h)	42.9° 20:20	10.32	81%	29.5°
2030-02-14 Thu	12	—	unknown	19:30–21:40 (marginal, 2.17 h)	42.9° 20:20	10.28	88%	34.4°
2030-02-15 Fri	14	—	unknown	19:30–22:30 (marginal, 3.0 h)	42.9° 20:15	10.24	94%	42.4°
2030-02-16 Sat	20	—	unknown	19:30–23:10 (marginal, 3.67 h)	42.9° 20:10	10.2	98%	52.4°
2030-02-17 Sun	28	—	unknown	19:30–23:25 (marginal, 3.92 h)	42.9° 20:05	10.16	100%	63.6°
2030-02-18 Mon	39	—	unknown	19:35–20:35 (good, 1.0 h)	42.9° 20:05	10.12	99%	75.4°
2030-02-19 Tue	65	—	unknown	19:35–22:20 (good, 2.75 h)	42.9° 20:00	10.08	96%	87.8°
2030-02-20 Wed	72	—	unknown	19:35–22:50 (good, 3.25 h)	42.9° 19:55	10.04	91%	100.2°
2030-02-21 Thu	76	—	unknown	19:35–23:00 (good, 3.42 h)	42.9° 19:50	10.0	83%	112.6°
2030-02-22 Fri	76	—	unknown	19:40–23:05 (good, 3.42 h)	42.9° 19:45	9.95	74%	124.6°
2030-02-23 Sat	75	—	unknown	19:40–23:00 (good, 3.33 h)	42.9° 19:45	9.91	63%	135.7°
2030-02-24 Sun	73	—	unknown	19:40–23:00 (good, 3.33 h)	42.9° 19:40	9.87	52%	144.9°
2030-02-25 Mon	72	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:35	9.82	40%	150.6°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2030-01-27&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.