Supernova SN 2013fw (ex PSN J21134481+1334335) in NGC 7042: image and spectroscopy (23/25 Oct. 2013)
Updates (30 Oct. 2013): the object received its official desigation SN 2013fw and our photometry and spectroscopic identification is reported on the CBET 3681 from the Central Bureau for Astronomical Telegrams. Here it is an extract from CBET 3681: “Masi, Schmeer and Nocentini add that several low-resolution spectrograms of 2013fw were obtained onOct. 25.74 remotely using a 36-cm telescope (+ 100 lines/mm grating, with adispersion of 3.47 nm/pixel) at Ceccano, which show a clear Si II absorptionaround 615.0 nm, suggesting that 2013fw is a type-Ia supernova.“
On 23 Oct 2013, the Virtual Telescope imaged the supernova candidate PSN J21134481+1334335 in NGC 7042 galaxy. Optical remote imaging with the PlaneWave 17″ robotic unit easily located the transient, found at mag. 16.5 R. The sky was not good enough for spectroscopy: the source was already critical, because of its faint brightness, and the hazy sky plus Moon made the rest.
On 25 Oct. the weather was just perfect and new optical images were captured again with the PlaneWave 17″ robotic unit, with the transient at mag. 16.2 R. The image above comes from the average of 6, 120-seconds exposures.
This time we tried to do spectroscopy, to understand if this one was a true supernova and, if yes, of what type. For this, we used the Celestron C14 robotic unit, equipped with a 100 lines/mm diffraction grating. After averaging six, 300-seconds spectra, we firmly detected the evidence of absorption at about 6150 angstroms, that is Si II. This is the clear signature of a type Ia supernova. Spectrum is shown below, both the original one and the version plotted with RSpec.
Observations were performed by G. Masi, F. Nocentini and P. Schmeer.
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