# circumstellar matter

## The Detection of a Type IIn Supernova in Optical Follow-up Observations of IceCube Neutrino Events

The IceCube neutrino observatory pursues a follow-up program selecting interesting neutrino events in real-time and issuing alerts for electromagnetic follow-up observations. In 2012 March, the most significant neutrino alert during the first three …

## Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium

Owing to their utility for measurements of cosmic acceleration, Type Ia supernovae (SNe Ia) are perhaps the best-studied class of SNe, yet the progenitor systems of these explosions largely remain a mystery. A rare subclass of SNe Ia shows evidence …

## Discovery of Bright Galactic R Coronae Borealis and DY Persei Variables: Rare Gems Mined from ACVS

We present the results of a machine-learning (ML)-based search for new R Coronae Borealis (RCB) stars and DY Persei-like stars (DYPers) in the Galaxy using cataloged light curves from the All-Sky Automated Survey (ASAS) Catalog of Variable Stars …

## SN 2010jp (PTF10aaxi): a jet in a Type II supernova

We present photometry and spectroscopy of the peculiar Type II supernova (SN) SN 2010jp, also named PTF10aaxi. The light curve exhibits a linear decline with a relatively low peak absolute magnitude of only -15.9 (unfiltered), and a low radioactive …

## SN 2008am: A Super-luminous Type IIn Supernova

We present observations and interpretation of the Type IIn supernova SN 2008am discovered by the ROTSE Supernova Verification Project (RSVP). SN 2008am peaked at approximately -22.3 mag at a redshift of z = 0.2338, giving it a peak luminosity of …

## New Observations of the Very Luminous Supernova 2006gy: Evidence for Echoes

Supernova (SN) 2006gy was a hydrogen-rich core-collapse SN that remains one of the most luminous optical SNe ever observed. The total energy budget (>2 × 10$^51$ erg radiated in the optical alone) poses many challenges for standard SN theory. We …

## SN 2008iy: an unusual Type IIn Supernova with an enduring 400-d rise time

We present spectroscopic and photometric observations of the Type IIn supernova (SN) 2008iy. SN 2008iy showed an unprecedentedly long rise time of åisebox-0.5ex 400 d, making it the first known SN to take significantly longer than 100 d to reach peak …

## Discovery of Precursor Luminous Blue Variable Outbursts in Two Recent Optical Transients: The Fitfully Variable Missing Links UGC 2773-OT and SN 2009ip

We present progenitor-star detections, light curves, and optical spectra of supernova (SN) 2009ip and the 2009 optical transient in UGC 2773 (U2773-OT), which were not genuine SNe. Precursor variability in the decade before outburst indicates that …

## Late-Time Observations of SN 2006gy: Still Going Strong

Owing to its extremely high luminosity and long duration, supernova (SN) 2006gy radiated more energy in visual light than any other known SN. Two hypotheses to explain its high luminosity at early times—that it was powered by shock interaction with …