GAIA G Band Photometric Monitoring of SN2023ixf in October 2023. Interesting Light Curve Feature Around MJD 60230.
ATel #16339; Peter Pessev (AIUB), Thomas Schildknecht (AIUB), Alessandro Vananti (AIUB), Lucia Kleint (AIUB)
on 16 Nov 2023; 18:32 UT
Credential Certification: Peter Pessev (peter.pessev@unibe.ch)
Subjects: Optical, Supernovae
Results of the regular photometric monitoring of the nearby Type II Supernova SN2023ixf from the Astronomical Institute of University of Bern (AIUB) Zimmerwald Observatory (MPC code 026) are presented. Data collection was carried out by the autonomous observing scheduler of the Observatory during all the nights with favorable weather conditions in the month of October/November 2023. The data was acquired in conjunction to the main mission of Zimmerwald, dedicated to near-Earth Space Safety and geodetic Satellite Laser Ranging observations. At every observing occasion, three consecutive 20 seconds images of M101 host galaxy were acquired with the 0.8m ZimMAIN Ritchey-Chretien Telescope, utilizing the full response of the Spectral Instruments SI1100 CCD camera. AstroImageJ (Collins et al. 2017) was utilized for the data reduction and photometry. Standard initial reduction was carried out, consisting of bias subtraction and flat field division, followed by fringe frames correction/subtraction. The individual images were then registered together, median combined and aperture photometry carried out on the resulting frame. Twelve nearby starts present in the GAIA DR3 catalog were used for the photometry calibration and the measurements below are presented as GAIA G band magnitudes.
Date MJD G Gerr Transp.
Oct. 02 2023 60219.897087245 14.28 0.03 Cirrus
Oct. 08 2023 60225.896639290 14.36 0.03 Cirrus
Oct. 09 2023 60226.897610290 14.364 0.019 Clear
Oct. 10 2023 60227.897552570 14.382 0.016 Clear
Oct. 11 2023 60228.897613400 14.358 0.012 Clear
Oct. 13 2023 60230.897057685 14.20 0.03 Cirrus
Oct. 31 2023 60248.897371740 14.52 0.04 Cirrus
Nov. 07 2023 60255.895973900 14.68 0.02 Cirrus
MJD in the compilation above corresponds to the mid-exposure time of the second image of the sequence (~ middle of the epoch of observation). The transparency note indicates if the conditions were clear or there was some cirrus present at the time of data acquisition. Cases of reduced atmospheric transparency are naturally resulting in increased uncertainties of the measured SN2023ixf magnitudes.
A monotonic steady increase of the measured magnitudes (object dimming) is observed up to Oct. 10, followed by an indication of a slight re-brightening on Oct. 11. The next measurement on Oct. 13 reveals a 0.17 +/- 0.03 magnitudes brightening of SN2023ixf in respect of the weighted mean of the Oct. 08 - 11 measurements (G = 14.37 +/- 0.01).
Unfortunately, next favorable weather conditions occurred about 18 days later and it was not possible to observe the event in more details. Images of the field were acquired on Oct. 21 and 28, but under extremely poor transparency. The two most recent observations on Oct. 31 and Nov. 07 follow the trend of dimming of the object after the brightening event. Two reported MASTER-Amur (Lipunov et al. 2009) measurements acquired with clear filter (14.4 and 14.5 mag.) on Oct. 27 2023 are in good agreement with the aforementioned trend of the Zimmerwald observations as well. A possible preliminary interpretation of the brightening could be a light echo phenomenon. More measurements are needed to study the light curve evolution in further details throughout October and better constrain the event. The regular photometric monitoring of SN2023ixf from the Zimmerwald Observatory will continue.
References:
Collins et al. 2017, AJ, 153, 77
Lipunov et al. 2010, Advances in Astronomy, 2010, article id. 349171
