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BVR photometry and CCD spectroscopy of nova Del 2013

ATel #5295; M. M.M. Santangelo and M. Pasquini
on 17 Aug 2013; 07:18 UT
Credential Certification: Filippo Mannucci (filippo@arcetri.astro.it)

Subjects: Optical, Nova

Referred to by ATel #: 5297, 5300

In the course of the CATS (Capannori Astronomical Transient Survey) project, M.M.M. Santangelo and M. Pasquini performed BVR photoelectric photometry and low resolution CCD long-slit spectrometry of nova Delphini 2013. The measurements were made with an Optec SSP-5A single channel photoelectric photometer (with a photomultiplier tube Hamamatsu R6358), and with a SBIG SGS spectrometer + CCD camera ST-7XME attached at OAC's 0.30-m f/10 Schmidt-Cassegrain telescope. The atmospheric extinction was measured with the method of Bouguer's lines. As comparison stars for the photometry we used HR 7811 (BV measurements only) and GSC 1644-1837 (BVR measurements). Pre-processing of the spectra included bias + dark + nightsky subtraction. The spectra were wavelength calibrated by means of Mercury and Neon lamps taken immediately after each nova spectrum, and they were flux calibrated by means of spectra of the spectrophotometric standard star Zeta Peg taken in the same night. Our spectra of nova Delphini 2013 were taken in two spectral ranges from 385.4 to 715.2 nm and from 591.0 to 920.8 nm, at the dispersion of 0.43 nm/pixel (resolution R ~ 1000), through a 18 mic wide long-slit. The results of our photoelectric photometry were as follows: 2013 Aug 15.873UT V = 5.112+/-0.003 B-V = +0.057+/-0.007, 2013 Aug 15.892UT V = 5.129+/-0.006 B-V = +0.024+/-0.012 V-R = +0.130+/-0.010. Our spectra of nova Delphini 2013, taken about two hours after our photoelectric photometry, showed strong P Cyg effect of the following lines: H alpha, H beta, H gamma, Fe II 492.4 nm + He I 492.2 nm, Fe II 501.8 nm + He I 501.6 nm, Fe II 516.9 nm + Fe I 516.7 nm, O I triplet 777.4 nm. Other spectral lines showing some P Cyg effect are: H delta, H epsilon, Si II 634.7 nm, Si II 637.1 nm. The emission is slightly asymmetric with a longer tail redward (right skewed). From the FWHM of the emission component of H alpha line we derived an expansion velocity of about 1800 km/s.