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: 02-23 (75), 02-22 (73), 02-24 (73), 02-25 (72), 02-21 (69) — by astronomy; check the weather when the night is within four days.

2038-02-13astronomy score per night — click a bar for that night2038-03-14

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2038-02-13 Sat	26	—	unknown	19:30–00:00 (marginal, 4.5 h)	42.9° 20:25	10.32	65%	27.4°
2038-02-14 Sun	17	—	unknown	19:30–23:35 (marginal, 4.08 h)	42.9° 20:20	10.28	74%	26.7°
2038-02-15 Mon	13	—	unknown	19:30–23:05 (marginal, 3.58 h)	42.9° 20:15	10.24	83%	31.4°
2038-02-16 Tue	13	—	unknown	19:30–22:25 (marginal, 2.92 h)	42.9° 20:10	10.2	90%	40.1°
2038-02-17 Wed	17	—	unknown	19:30–23:00 (marginal, 3.5 h)	42.9° 20:05	10.16	96%	51.1°
2038-02-18 Thu	25	—	unknown	19:35–23:15 (marginal, 3.67 h)	42.9° 20:05	10.12	99%	63.3°
2038-02-19 Fri	36	—	unknown	19:35–20:00 (good, 0.42 h)	42.9° 20:00	10.08	100%	76.2°
2038-02-20 Sat	48	—	unknown	19:35–22:05 (good, 2.5 h)	42.9° 19:55	10.04	98%	89.5°
2038-02-21 Sun	69	—	unknown	19:35–22:50 (good, 3.25 h)	42.9° 19:50	10.0	92%	102.9°
2038-02-22 Mon	73	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:45	9.95	85%	116.0°
2038-02-23 Tue	75	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:45	9.91	76%	128.4°
2038-02-24 Wed	73	—	unknown	19:40–23:00 (good, 3.33 h)	42.9° 19:40	9.87	65%	139.6°
2038-02-25 Thu	72	—	unknown	19:40–22:55 (good, 3.25 h)	42.9° 19:35	9.82	54%	148.6°
2038-02-26 Fri	69	—	unknown	19:45–22:50 (good, 3.08 h)	42.9° 19:30	9.78	43%	153.4°
2038-02-27 Sat	69	—	unknown	19:45–22:45 (good, 3.0 h)	42.9° 19:30	9.73	32%	152.2°
2038-02-28 Sun	66	—	unknown	19:45–22:45 (good, 3.0 h)	42.9° 19:25	9.69	23%	146.0°
2038-03-01 Mon	65	—	unknown	19:45–22:40 (good, 2.92 h)	42.9° 19:20	9.64	15%	137.1°
2038-03-02 Tue	63	—	unknown	19:45–22:35 (good, 2.83 h)	42.9° 19:15	9.6	9%	127.0°
2038-03-03 Wed	61	—	unknown	19:50–22:30 (good, 2.67 h)	42.9° 19:10	9.55	4%	116.4°
2038-03-04 Thu	60	—	unknown	19:50–22:25 (good, 2.58 h)	42.9° 19:10	9.5	1%	105.6°
2038-03-05 Fri	58	—	unknown	19:50–22:25 (good, 2.58 h)	42.9° 19:05	9.46	0%	94.8°
2038-03-06 Sat	56	—	unknown	19:50–22:20 (good, 2.5 h)	42.9° 19:00	9.41	1%	84.1°
2038-03-07 Sun	54	—	unknown	19:55–22:15 (good, 2.33 h)	42.9° 18:55	9.36	4%	73.5°
2038-03-08 Mon	50	—	unknown	19:55–22:10 (good, 2.25 h)	42.9° 18:50	9.32	8%	63.1°
2038-03-09 Tue	46	—	unknown	19:55–22:05 (good, 2.17 h)	42.9° 18:50	9.27	14%	53.1°
2038-03-10 Wed	40	—	unknown	19:55–21:55 (good, 2.0 h)	42.9° 18:45	9.22	21%	43.6°
2038-03-11 Thu	32	—	unknown	20:00–21:40 (good, 1.67 h)	42.9° 18:40	9.17	29%	35.2°
2038-03-12 Fri	25	—	unknown	20:00–21:25 (good, 1.42 h)	42.9° 18:35	9.12	38%	28.9°
2038-03-13 Sat	19	—	unknown	20:00–22:20 (marginal, 2.33 h)	42.9° 18:35	9.07	48%	26.5°
2038-03-14 Sun	14	—	unknown	20:00–22:05 (marginal, 2.08 h)	42.9° 18:30	9.02	58%	29.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2038-02-13&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.