Erratum of ATEL #16315: Observations of comet 12P/Pons-Brooks after the July 19, 2023 outburst

ATel #16316; Alberto Silva Betzler (UFRB-CETENS, Brazil), Adam Popowicz (Silesian University of Technology, Gliwice, Poland), Orahcio Felicio de Sousa (UFRB-CFP, Brazil)
on 1 Nov 2023; 15:35 UT
Credential Certification: Alberto Betzler (betzler@ufrb.edu.br)

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The conclusions about the relationship between the V magnitudes and the B-V color and photometric aperture radii on ATEL #16315 are incorrect. During data processing, ASB inadvertently reversed the order of the aperture radii. In reality, after correction, the V apparent magnitude decreased, while B-V became redder with increasing radius. Figures 2 and 3 have been replaced with their correct versions. The correct conclusions can be found below. We apologize for this unfortunate error.
There was a color gradient of the coma along the radius r described approximately by B-V=(0.3+/-0.2)+(0.2+/-0.2)*log10(r) for 4.1 =< r =< 9.6 arcsec (dashed red line, Figure 2). This suggests that the coma had a uniform color, bluer than that of the Sun, regardless of the aperture radius r, or that the coma became redder with increasing distance from the optocenter. The model for the B-V color of the coma proposed by Betzler et. al (2017,AdSpR,60, 612) assumes that the brightness profile of coma I is proportional to 1/r^m, with the exponent m for the steady state equal to 1, which is far from the observational reality with complex structures in the coma. The condition that the coma is outside the steady state can be indirectly demonstrated by analyzing the relation between the magnitude V and the radius r, given by V=c0+2.5(m-2)*log10(r), where c0 is the magnitude of the coma's optocenter. Fitting the last equation with five measured V magnitudes with aperture radii between 4.1 and 9.6 arcsec gives V=(17.4+/-0.4)+(-3.9+/-0.5)*log10(r) (solid red line, Figure 3 ). The exponent m < 1 obtained from the fitted curve indicates that the dust is pushed into the tail by solar radiation and replenishes the antisolar regions (Ivanova et al, 2015, P&SS, 118,199).