Discovered by Patrick Wiggins on 2026-07-08 06:31:30 in NGC3310 at 12.9 mag (Clear, near Erda Utah, USA, TNS N°313386, https://www.wis-tns.org/object/2026sqf/discovery-cert ) classified by Claudio Balcon (TNS N°24188, https://www.wis-tns.org/object/2026sqf/classification-cert ) as a SN II. RAPAS ProAm network monitors the rise of SN 2026sqf from 2026-07-08-07 up to now and will follow it later on. During this period, 4 telescopes located in France, using the set of RAPAS G, Gbp and Grp filters meeting the three Gaia G, Gbp and Grp photometric band specifications, collected 10 measurements in 1 or the 3 Gaia bands through the two weeks following the discovery. The photometric consistency was ensured by reducing each frame with the corresponding Gaia DR3 reference catalog for G, Gbp and Grp bands.
SN 2026sqf is located just outside of the disk of its host galaxy NGC 3310, aperture photometry is slightly contaminated by the underlying galaxy light.
The multi-band light curve shows the supernova brightening at approximately −0.1 mag/day in G-band from 12.9 G mag on July 10 to 11.7 mag on July 21. The Color Index Gbp−Grp increased from +0.17 ± 0.05 to +0.47 ± 0.1, indicating a slightly decreasing temperature while the supernova is approaching maximum light.
The 6 spectra was obtained by Christian Buil with Tiny Star’Ex spectrograph on N256 (July 17, 18, 20), by Jean-Philippe Nougayrède with Alpy 600 spectrograph on N200 (July 18) and Pierre Jean Mercier with Alpy 600 on SC400 (July 19, 21). The SED displays a blue signature with Balmer Halpha (x2.9 the continuum) Balmer Hbeta, Hgamma, Hdelta and HeI lines, however absolute levels from spectra were not obtained but could be recovered thanks to photometry obtained the same nights. The narrowness of the emission lines suggest they are coming from the shocked CSM. Christian Buil delivered an additional R16000 spectra of Halpha line on July 22. The galaxy radial velocity is 989km/s (helio). The measured FWHM velocity is 97 ± 10 km/s, compared with an instrumental FWHM of 19 km/s. This velocity is likely associated with the circumstellar material that surrounded the progenitor prior to the event. This SN could be classified as a SN Ia CSM (CircumStellar Medium) with a white dwarf embedded in H rich cloud ejected from a previous stage of the binary system. It gives these strong H and He lines in the spectra.
Detailed light curves and data are going to be available on the RAPAS web page and Astro-COLIBRI web page on the following links :
https://rapas.imcce.fr/SN2026sqf-lightcurves.jpg
https://rapas.imcce.fr/SN2026sqf-mag-vs-bp-rp-index.jpg
https://rapas.imcce.fr/SN2026sqf_RAPAS.csv
https://rapas.imcce.fr/SN2026sqf-SED-20260717.png
https://rapas.imcce.fr/SN2026sqf-SED-20260718.png
https://rapas.imcce.fr/SN2026sqf-SED-20260717-18-20.png
https://rapas.imcce.fr/SN2026sqf-SED-20260719.png
https://rapas.imcce.fr/SN2026sqf-SED-20260721.png
https://rapas.imcce.fr/SN2026sqf-Ha-20260722.png
Further details and the full dataset are accessible to registered users of the RAPAS Spreadsheets platform. FITS Files are available on simple request.
Acknowledgements :
RAPAS ( https://gemini.obspm.fr/20220101-rapas/ ) is a ProAm collaboration created by T. Midavaine (SAF), W. Thuillot (LTE, Obs. de Paris-PSL) and M. Dennefeld (IAP/CNRS and Sorbonne Univ.) and funded by the Paris Observatory under API ProAm of the Scientific Council. It aims at homogenizing observing procedures and filters, and is delivering to a network of french amateur observatories a set of 3 filters which have been chosen to meet the Gaia G, Gbp and Grp spectral bands. This network produces data on astrophysical alerts delivered by various Alert systems (Gaia Alerts, Atlas, ZTF, etc…) and collected by Astro-COLIBRI ( https://astro-colibri.science ). It is similarly progressing towards an homogeneous spectroscopic equipment to deliver SED. Paris Observatory PADC is on the way to archive all the FITS files with attached processing pipeline.
Comments