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Discovery and Classification of 3 Type Supernovae by ATLAS

ATel #8680; J. Tonry, L. Denneau, B. Stalder, A. Heinze, A. Sherstyuk (IfA, University of Hawaii), A. Rest (STScI), K. W. Smith, S. J. Smartt (Queen's University Belfast)
on 11 Feb 2016; 21:10 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Brian Stalder (stalder@ifa.hawaii.edu)

Subjects: Optical, Supernovae, Transient

Referred to by ATel #: 8682, 8708, 8805, 8820, 8839, 8864, 8876, 9110, 9126, 9131, 9145, 9151

The ATLAS project (?http://fallingstar.com) is a pair of 0.5m f/2.0 Schmidt telescopes situated on Mauna Loa and Haleakala in Hawaii (Tonry 2011, PASP, 123, 58). Each telescope is equipped with an STA-1600 10.5x10.5k CCD with 1.86 arcsec pixels giving a FOV of 5.4x5.4 degrees. The first ATLAS unit has been installed on Haleakala and is robotically surveying the sky, covering up to 18,000 square degrees per night with exposure times of 30s. The current observing pattern uses dithered quads across a sky survey area of 4500 square degrees per night. The design sensitivity is around m ~ 20 AB mag in two broad filters (cyan and orange). The sky coverage will triple as overheads are reduced and when the second unit is installed on Mauna Loa in 2016. The primary mission for ATLAS is to act as an asteroid impact early warning system and find near earth objects, but in the course of the ATLAS sky survey it will find a wealth of stationary transients and variables. We intend to make the transient discoveries public with a minimum of delay. Discoveries are made through a custom built difference imaging pipeline and deep reference sky frames, cross-matched against known star, galaxy and transient catalogues.

Here we report the first discoveries of transients that we have spectroscopically confirmed. We discovered these with internal ATLAS survey names as below, and IAU names were registered with the TNS. Spectra were taken on the UH 2.2m + SNIFS spectrometer on 2016-02-08, and the transients are confirmed to be SNe of the following types (from SNID). Redshifts are from the host galaxies. Magnitudes are in the AB system (c denotes the cyan filter, o the orange filter).

Name     | ATLAS name |  RA (J2000) | Dec (J2000) | Disc. Date | Disc Mag  |   z    |  Type |  Phase | Notes  
SN2016adn| ATLAS16aae | 03:10:34.45 | +04:16:10.8 | 57421.3    |   16.51 c | 0.0232 |   Ia  |   max  | 1. 
SN2016ado| ATLAS16aaf | 02:03:05.78 | -03:50:28.3 | 57408.3    |   17.10 o | 0.0425 |   Ia  |   max  | 2.  
SN2016adp| ATLAS16aab | 03:21:42.40 | +42:05:49.7 | 57409.3    |   16.48 o | 0.0180 |   Ia  |+15-20d | 3.  

1. Also found as ASASSN-16bn (ATel #8660), classified by Balam et al. (ATel#8674) on 2015-02-11
2. Some similarities to SN2008ae within a week of max
3. Good match to a reddened 1991g-like at 2-3 weeks past max.