Addendum to ATel #16857
ATel #16862; Federico Manzini, Virginio Oldani (Stazione Astronomica di Sozzago), Paolo Ochner (Padova University), Luigi R. Bedin (INAF-OAPd), Andrea Reguitti (INAF-OABr), Andrea Farina (Padova University)
on 11 Oct 2024; 09:13 UT
Credential Certification: Andrea Reguitti (andreareguitti@gmail.com)
Subjects: Optical, Comet, Solar System Object
In ATel #16857, we analyzed all the public images taken with the r filter, available in the Science Archive of LCO (https://archive.lco.global/) to determine the nuclear magnitude of comet C/2024 S1. The analysis was conducted with a circular photometric aperture of 10 pixels in diameter and with comparison stars from the GAIA catalog. The measured instrumental magnitude for JD 2460593.62708 (2024-10-03 18:26UT) is 17.19+-0.16, while for JD 2460380.26806 (2024-10-08 03:03UT) is 17.95+-0.07, showing a decrease of about 0.7 magnitudes.
The measurement of the elongation of the nuclear area, which would suggest a fragmentation of the nucleus itself, was measured drawing a 100-pixel photometric cut across the nucleus with the same angle as the PA of the Sun (83 deg), assuming its elongation was in that direction, and was not due to the motion of the comet, which was actually directed to a different PA (103-105 deg) (Figure 5).
The image stacks of October 3 and October 8 were rescaled to the same background values for a direct comparison and the measurement was performed at the mean value between the background and the peak of maximum brightness. On the two dates the amplitude of the curve was respectively 52+-2 pixels (18512+-712 km on the sky plane at the distance of the comet) and 55+-4 pixels, corresponding to 17765+-1292 km. The uncertainty of this value is given by the very irregular shape of the photometric cut curve (Figure 4).
This work used observations made as part of the Comet Chasers schools outreach project. The observations included in this study were made by Mirjana Malaric and students from Zagreb, Croatia and Helen Usher, Wales, UK. The project is funded by the UK Science and Technology Facilities Council through the DeepSpace2DeepImpact Project, the Open University and Cardiff University. It accesses the LCOGT telescopes through the Faulkes Telescope Project (FTPEPO2014A-004), which is partly funded by the Dill Faulkes Educational Trust.
