The schmidt 67/92 robotic telescope - roboschmidt user manual

The 67/91 Schmidt telescope is the largest instrument of this type in Italy. It was officially commissioned in 1966; in 1991 the telescope was moved to mount Ekar, near the Copernico 1.82m telescope, in order to take advantage of the higher altitude and lower light pollution. In 2017 the telescope has been considerably refurbished (new CCD camera, new filters, autoguider) and remotely controlled. Starting from May, 2020 updates of both hardware and software allowed the implementation of the fully robotic operational mode . The observing blocks (OB) are submitted at any time by the PIs of the proposals or their collaborators. The Robotic System has a rapid-response capability that allows it to interrupt regular observations in order to observe transient phenomena with high priority

Optical observations of a SN 2002cx-like peculiar supernova SN 2013en in UGC 11369

We present optical observations of a SN 2002cx-like supernova SN 2013en in UGC 11369, spanning from a phase near maximum light (t= +1 d) to t= +60 d with respect to the R-band maximum. Adopting a distance modulus of mu=34.11 +/- 0.15 mag and a total extinction (host galaxy+Milky Way) of $A_V \sim1.5$ mag, we found that SN 2013en peaked at $M(R)\sim -18.6$ mag, which is underluminous compared to the normal SNe Ia. The near maximum spectra show lines of Si II, Fe II, Fe III, Cr II, Ca II and other intermediate-mass and iron group elements which all have lower expansion velocities (i.e., ~ 6000 km/s). The photometric and spectroscopic evolution of SN 2013en is remarkably similar to those of SN 2002cx and SN 2005hk, suggesting that they are likely to be generated from a similar progenitor scenario or explosion mechanism.Comment: 8 pages, 8 figures, 3 tables, accepted for publication in MNRA

A high resolution, multi-epoch spectral atlas of peculiar stars including RAVE, GAIA and HERMES wavelength ranges

We present an Echelle+CCD, high S/N, high resolution (R = 20\,000) spectroscopic atlas of 108 well-known objects representative of the most common types of peculiar and variable stars. The wavelength interval extends from 4600 to 9400 Ang, and includes the RAVE, Gaia and HERMES wavelength ranges. Multi-epoch spectra are provided for the majority of observed stars. A total of 425 spectra of peculiar stars are presented, which have been collected during 56 observing nights between November 1998 and August 2002. The spectra are given in FITS format and heliocentric wavelengths, with accurate subtraction of both the sky background and the scattered light. Auxiliary material useful for custom applications (telluric dividers, spectro-photometric stars, flat-field tracings) is also provided. The atlas aims to provide a homogeneous database of the spectral appearance of stellar peculiarities, a tool useful both for classification purposes and inter-comparison studies. It could also serve the planning for and training of automated classification algorithms designed for RAVE, Gaia, HERMES and other large scale spectral surveys. The spectrum of XX Oph is discussed in some detail as an example of the content of the present atlas.Comment: AJ in press (issue 140:6 December 2010

The spectacular evolution of Supernova 1996al over 15 years: a low energy explosion of a stripped massive star in a highly structured environment

Spectrophotometry of SN 1996al carried out throughout 15 years is presented. The early photometry suggests that SN 1996al is a Linear type-II supernova, with an absolute peak of Mv ~ -18.2 mag. Early spectra present broad, asymmetric Balmer emissions, with super-imposed narrow lines with P-Cygni profile, and He I features with asymmetric, broad emission components. The analysis of the line profiles shows that the H and He broad components form in the same region of the ejecta. By day +142, the Halpha profile dramatically changes: the narrow P-Cygni profile disappears, and the Halpha is fitted by three emission components, that will be detected over the remaining 15 yrs of the SN monitoring campaign. Instead, the He I emissions become progressively narrower and symmetric. A sudden increase in flux of all He I lines is observed between 300 and 600 days. Models show that the supernova luminosity is sustained by the interaction of low mass (~1.15 Msun) ejecta, expelled in a low kinetic energy (~ 1.6 x 10^50 erg) explosion, with highly asymmetric circumstellar medium. The detection of Halpha emission in pre-explosion archive images suggests that the progenitor was most likely a massive star (~25 Msun ZAMS) that had lost a large fraction of its hydrogen envelope before explosion, and was hence embedded in a H-rich cocoon. The low-mass ejecta and modest kinetic energy of the explosion are explained with massive fallback of material into the compact remnant, a 7-8 Msun black hole.Comment: 27 pages, 23 figures, Accepted for publication in MNRA

Supersolar Ni/Fe production in the Type IIP SN 2012ec

SN 2012ec is a Type IIP supernova (SN) with a progenitor detection and comprehensive photospheric-phase observational coverage. Here, we present Very Large Telescope and PESSTO observations of this SN in the nebular phase. We model the nebular [O I] 6300, 6364 lines and find their strength to suggest a progenitor main-sequence mass of 13-15 Msun. SN 2012ec is unique among hydrogen-rich SNe in showing a distinct and unblended line of stable nickel [Ni II] 7378. This line is produced by 58Ni, a nuclear burning ash whose abundance is a sensitive tracer of explosive burning conditions. Using spectral synthesis modelling, we use the relative strengths of [Ni II] 7378 and [Fe II] 7155 (the progenitor of which is 56Ni) to derive a Ni/Fe production ratio of 0.20pm0.07 (by mass), which is a factor 3.4pm1.2 times the solar value. High production of stable nickel is confirmed by a strong [Ni II] 1.939 micron line. This is the third reported case of a core-collapse supernova producing a Ni/Fe ratio far above the solar value, which has implications for core-collapse explosion theory and galactic chemical evolution models.Comment: Published versio

Spectropolarimetry of Galactic stars with anomalous extinction sightlines

Highly reddened type Ia Supernovae (SNe Ia) with low total-to-selective visual extinction ratio values, $R_V$, also show peculiar linear polarization wavelength dependencies with peak polarizations at short wavelengths ($\lambda_{max} \lesssim 0.4 \mu m$). It is not clear why sightlines to SNe Ia display such different continuum polarization profiles from interstellar sightlines in the Milky Way with similar $R_V$ values. We investigate polarization profiles of a sample of Galactic stars with low $R_V$ values, along anomalous extinction sightlines, with the aim to find similarities to the polarization profiles that we observe in SN Ia sightlines. We undertook spectropolarimetry of 14 stars, and used archival data for three additional stars, and run dust extinction and polarization simulations to infer a simple dust model that can reproduce the observed extinction and polarization curves. Our sample of Galactic stars with low $R_V$ values and anomalous extinction sightlines displays normal polarization profiles with an average $\lambda_{max} \sim 0.53 {\mu m}$, and is consistent within 3$\sigma$ to a larger coherent sample of Galactic stars from literature. Despite the low $R_V$ values of dust towards the stars in our sample, the polarization curves do not show any similarity to the continuum polarization curves observed towards SNe Ia with low $R_V$ values. There is a correlation between the best-fit Serkowski parameters $K$ and $\lambda_{max}$, but we did not find any significant correlation between $R_V$ and $\lambda_{max}$. Our simulations show that the $K-\lambda_{max}$ relationship is an intrinsic property of polarization. Furthermore, we have shown that in order to reproduce polarization curves with normal $\lambda_{max}$ and low $R_V$ values, a population of large (a $\geq 0.1 \mu m$) interstellar silicate grains must be contained in the dust's composition.Comment: accepted for publication in A&