Long-term monitoring of comet 29P/Schwassmann-Wachmann 1 from Lulin observatory

<div class="textLayer"><span dir="ltr" role="presentation">Multi-band photometric monitoring of comet 29P/Schwassmann-Wachmann 1 was </span><span dir="ltr" role="presentation">conducted on the standard Johnson-Cousins filter set, and the observations were </span><span dir="ltr" role="presentation">spanning from July 2018 to December 2021. The comet detected at least twelve </span><span dir="ltr" role="presentation">relatively large outbursts, during which its brightness increased by 1.5 to 5 mag. as </span><span dir="ltr" role="presentation">measured through a 5 arcsec aperture. The variation of the cometary brightness profile </span><span dir="ltr" role="presentation">is clear to be found during the outbursts. The derived slope of the surface brightness </span><span dir="ltr" role="presentation">profiles are significantly varying with time from the shallower slope to a steeper one </span><span dir="ltr" role="presentation">at the beginning of each outburst and then slowly back to pre-outburst values. The </span><span dir="ltr" role="presentation">color indices seem to not be obviously changing as outbursts occurred. But for the </span><span dir="ltr" role="presentation">quadruple outbursts in late September of 2021, we can confidently spot the change in </span><span dir="ltr" role="presentation">the color of the comet, and point out that the color indices seem to be lower than the </span><span dir="ltr" role="presentation">mean values, especially in B-V. Dust production derived by using the parameter Af</span><span dir="ltr" role="presentation">ρ </span><span dir="ltr" role="presentation">from R-band photometry measurements shows a large increasing trend accompa</span><span dir="ltr" role="presentation">nied by outbursts. Using a simple model and the derived outflow velocity of 0.11 km </span><span dir="ltr" role="presentation">s</span><span dir="ltr" role="presentation">−</span><span dir="ltr" role="presentation">1</span> <span dir="ltr" role="presentation">from the expanding shell features, an estimated lower limit of 1.0</span> <span dir="ltr" role="presentation">×</span> <span dir="ltr" role="presentation">10</span><sup><span dir="ltr" role="presentation">8</span></sup> <span dir="ltr" role="presentation">kg and </span><span dir="ltr" role="presentation">2.7</span> <span dir="ltr" role="presentation">×</span> <span dir="ltr" role="presentation">10</span><sup><span dir="ltr" role="presentation">9</span></sup> <span dir="ltr" role="presentation">kg of dust was released during the quadruple outbursts using the specific </span><span dir="ltr" role="presentation">dust size, 1</span> <span dir="ltr" role="presentation">μ</span><span dir="ltr" role="presentation">m.</span></div> <div class="annotationLayer"> </div>