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: 01-03 (93), 01-04 (93), 01-05 (93), 01-06 (93), 01-07 (93) — by astronomy; check the weather when the night is within four days.

2027-01-02astronomy score per night — click a bar for that night2027-01-31

night of	astronomy	weather	overall	best window	highest	dark h	Moon	Moon sep.
2027-01-02 Sat	84	—	unknown	02:15–06:10 (good, 3.92 h)	50.2° 06:00	11.44	20%	43.8°
2027-01-03 Sun	93	—	unknown	02:10–06:10 (good, 4.0 h)	50.2° 05:55	11.43	13%	55.7°
2027-01-04 Mon	93	—	unknown	02:05–06:10 (good, 4.08 h)	50.2° 05:55	11.42	8%	67.5°
2027-01-05 Tue	93	—	unknown	02:00–06:10 (good, 4.17 h)	50.2° 05:50	11.41	3%	79.2°
2027-01-06 Wed	93	—	unknown	02:00–06:10 (good, 4.17 h)	50.2° 05:45	11.39	1%	90.9°
2027-01-07 Thu	93	—	unknown	01:55–06:10 (good, 4.25 h)	50.2° 05:40	11.38	0%	102.6°
2027-01-08 Fri	93	—	unknown	01:50–06:10 (good, 4.33 h)	50.2° 05:40	11.36	1%	114.3°
2027-01-09 Sat	93	—	unknown	01:45–06:10 (good, 4.42 h)	50.2° 05:35	11.35	4%	126.0°
2027-01-10 Sun	93	—	unknown	01:45–06:10 (good, 4.42 h)	50.2° 05:30	11.33	8%	137.8°
2027-01-11 Mon	93	—	unknown	01:40–06:10 (good, 4.5 h)	50.2° 05:25	11.31	14%	149.5°
2027-01-12 Tue	93	—	unknown	01:35–06:10 (good, 4.58 h)	50.2° 05:20	11.29	22%	160.9°
2027-01-13 Wed	93	—	unknown	01:30–06:10 (good, 4.67 h)	50.2° 05:20	11.27	31%	170.3°
2027-01-14 Thu	93	—	unknown	01:25–06:10 (good, 4.75 h)	50.2° 05:15	11.25	40%	168.3°
2027-01-15 Fri	93	—	unknown	01:25–06:10 (good, 4.75 h)	50.2° 05:10	11.23	51%	157.3°
2027-01-16 Sat	93	—	unknown	01:25–06:10 (good, 4.75 h)	50.2° 05:05	11.21	62%	144.5°
2027-01-17 Sun	93	—	unknown	01:25–06:10 (good, 4.75 h)	50.2° 05:00	11.19	72%	130.9°
2027-01-18 Mon	93	—	unknown	01:25–06:10 (good, 4.75 h)	50.2° 05:00	11.16	82%	116.8°
2027-01-19 Tue	92	—	unknown	01:30–06:10 (good, 4.67 h)	50.2° 04:55	11.14	90%	102.2°
2027-01-20 Wed	65	—	unknown	02:50–06:10 (good, 3.33 h)	50.2° 04:50	11.11	96%	87.3°
2027-01-21 Thu	47	—	unknown	05:10–06:05 (good, 0.92 h)	50.2° 04:45	11.09	100%	72.2°
2027-01-22 Fri	32	—	unknown	01:10–06:05 (marginal, 4.92 h)	50.2° 04:45	11.06	100%	57.2°
2027-01-23 Sat	22	—	unknown	02:05–06:05 (marginal, 4.0 h)	50.2° 04:40	11.04	97%	42.4°
2027-01-24 Sun	19	—	unknown	02:50–06:05 (marginal, 3.25 h)	50.2° 04:35	11.01	92%	28.2°
2027-01-25 Mon	24	—	unknown	00:50–06:05 (marginal, 5.25 h)	50.2° 04:30	10.98	84%	15.2°
2027-01-26 Tue	33	—	unknown	00:25–06:05 (marginal, 5.67 h)	50.2° 04:25	10.95	75%	8.6°
2027-01-27 Wed	47	—	unknown	00:10–06:05 (marginal, 5.92 h)	50.2° 04:25	10.92	65%	16.8°
2027-01-28 Thu	73	—	unknown	00:30–06:05 (good, 5.58 h)	50.2° 04:20	10.89	55%	28.6°
2027-01-29 Fri	87	—	unknown	00:30–06:00 (good, 5.5 h)	50.2° 04:15	10.86	45%	40.7°
2027-01-30 Sat	92	—	unknown	00:25–06:00 (good, 5.58 h)	50.2° 04:10	10.83	36%	52.7°
2027-01-31 Sun	93	—	unknown	00:20–06:00 (good, 5.67 h)	50.2° 04:05	10.8	27%	64.5°

Download: CSV · JSON

💡 API

curl -sS "https://devops.majbase.com/rozhen-planner/calendar-api?target=M31&date=2027-01-02&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.