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: 02-18 (93), 02-19 (93), 02-20 (93), 02-21 (93), 02-22 (93) — by astronomy; check the weather when the night is within four days.

2042-02-18astronomy score per night — click a bar for that night2042-03-19

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2042-02-18 Tue	93	—	unknown	23:10–05:40 (good, 6.5 h)	50.1° 02:55	10.12	3%	125.5°
2042-02-19 Wed	93	—	unknown	23:05–05:40 (good, 6.58 h)	50.1° 02:50	10.08	0%	140.4°
2042-02-20 Thu	93	—	unknown	23:00–05:40 (good, 6.67 h)	50.1° 02:50	10.04	1%	155.4°
2042-02-21 Fri	93	—	unknown	22:55–05:35 (good, 6.67 h)	50.1° 02:45	9.99	4%	170.3°
2042-02-22 Sat	93	—	unknown	22:55–05:35 (good, 6.67 h)	50.1° 02:40	9.95	10%	173.6°
2042-02-23 Sun	93	—	unknown	22:50–05:35 (good, 6.75 h)	50.1° 02:35	9.91	18%	159.3°
2042-02-24 Mon	93	—	unknown	22:50–05:30 (good, 6.67 h)	50.1° 02:30	9.86	28%	145.0°
2042-02-25 Tue	93	—	unknown	22:45–05:30 (good, 6.75 h)	50.1° 02:30	9.82	39%	131.0°
2042-02-26 Wed	93	—	unknown	22:45–05:30 (good, 6.75 h)	50.1° 02:25	9.78	50%	117.4°
2042-02-27 Thu	93	—	unknown	22:50–05:30 (good, 6.67 h)	50.1° 02:20	9.73	60%	104.2°
2042-02-28 Fri	89	—	unknown	22:55–05:25 (good, 6.5 h)	50.1° 02:15	9.69	70%	91.4°
2042-03-01 Sat	84	—	unknown	00:10–05:25 (good, 5.25 h)	50.1° 02:15	9.64	79%	78.7°
2042-03-02 Sun	63	—	unknown	02:25–05:25 (good, 3.0 h)	50.1° 02:10	9.6	86%	66.4°
2042-03-03 Mon	47	—	unknown	22:30–05:20 (marginal, 6.83 h)	50.1° 02:05	9.55	92%	54.1°
2042-03-04 Tue	33	—	unknown	00:00–05:20 (marginal, 5.33 h)	50.1° 02:00	9.5	97%	42.1°
2042-03-05 Wed	21	—	unknown	02:45–05:20 (marginal, 2.58 h)	50.1° 01:55	9.46	99%	30.1°
2042-03-06 Thu	20	—	unknown	03:10–05:15 (marginal, 2.08 h)	50.1° 01:55	9.41	100%	18.3°
2042-03-07 Fri	20	—	unknown	03:00–05:15 (marginal, 2.25 h)	50.1° 01:50	9.36	99%	6.9°
2042-03-08 Sat	24	—	unknown	22:00–05:15 (marginal, 7.25 h)	50.1° 01:45	9.31	96%	6.3°
2042-03-09 Sun	34	—	unknown	21:40–05:10 (marginal, 7.5 h)	50.1° 01:40	9.27	92%	17.7°
2042-03-10 Mon	67	—	unknown	21:50–22:10 (good, 0.33 h)	50.1° 01:35	9.22	86%	29.5°
2042-03-11 Tue	85	—	unknown	21:45–00:50 (good, 3.08 h)	50.1° 01:35	9.17	78%	41.4°
2042-03-12 Wed	91	—	unknown	21:45–03:45 (good, 6.0 h)	50.1° 01:30	9.12	70%	53.5°
2042-03-13 Thu	93	—	unknown	21:40–04:50 (good, 7.17 h)	50.1° 01:25	9.07	60%	65.9°
2042-03-14 Fri	93	—	unknown	21:35–05:00 (good, 7.42 h)	50.1° 01:20	9.02	50%	78.6°
2042-03-15 Sat	93	—	unknown	21:30–05:00 (good, 7.5 h)	50.1° 01:20	8.97	40%	91.6°
2042-03-16 Sun	93	—	unknown	21:25–05:00 (good, 7.58 h)	50.1° 01:15	8.92	30%	105.1°
2042-03-17 Mon	93	—	unknown	21:25–04:55 (good, 7.5 h)	50.1° 01:10	8.87	20%	119.1°
2042-03-18 Tue	93	—	unknown	21:20–04:55 (good, 7.58 h)	50.1° 01:05	8.82	11%	133.5°
2042-03-19 Wed	93	—	unknown	21:15–04:55 (good, 7.67 h)	50.1° 01:00	8.77	5%	148.3°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2042-02-18&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.