1304 Arosa asteroid is yet another main belt object that orbits the Sun in 5 years and 9 months. Arosa diameter is estimated to 40km, and it is actually pretty faint – apparent magnitude is about 14 mag. It was discovered in 1928, and its name comes from Swiss mountain village Arosa. This asteroid is a good target for amateur photometry due to its fast rotation period.

Last two nights were actually first nights this year I was able to plan some observations and also complete them 🙂 Conditions were not perfect, transparency was poor due to high clouds presence, so photometry data quality is not high plus at current orientation amplitude of changes is about 0.1mag. Nevertheless I was able to collect about 5 hours of exposures that is about 2/3 of asteroid rotational period. At that time Arosa was moving near border between Ursa Major and Leo constellations. During 5 hours it travelled about 315,000 km.

I used Muniwin software to perform actual photometry. Muniwin has a nice feature that can follow moving photometry targets automatically. You just need to select two or more key frames, and all positions will be calculated upon them.

1304 Arosa lightcurve
1304 Arosa lightcurve
Stacked capture data with asteroid path
Stacked capture data with asteroid path
Technical data:

Date: 26.02.2019
Location: Nieborowice, Poland
Telescope: Meade ACF 10"
Corrector: AP CCDT67
Camera: QHY163M, gain 100
Mount: SW EQ6
Guiding: SW 80/400 + ASI290MM
Exposures: 150 x 120s, L filter
Conditions: suburban sky, seeing good, transparency poor

Reference star: UCAC4-604-048321 (13.92mag)