DRAFT
2021-02-02 13:26:17
Type: Object/s-Discovery/Classification
ATLAS21dic (AT2021blu): discovery of a transient in UGC 05829 (8 Mpc)
Authors: K. W. Smith, S. Srivastav, O. McBrien, S. J. Smartt, J. Gillanders, M. Fulton, D. R. Young, L. Shingles, M. McCollum (Queen's University Belfast), T.-W. Chen (Stockholm), J. Anderson (ESO), L. Denneau, A. Heinze, J. Tonry, H. Weiland (IfA, University of Hawaii), B. Stalder (LSST), A. Rest (STScI), D. E. Wright (University of Minnesota)
Source Group: ATLAS
Keywords: Supernova
Abstract:
Here we report the ATLAS discovery of the transient ATLAS21dic (AT2021blu) in galaxy UGC 05829 at magnitude m_o = 18.49 +/- 0.18. At a distance of 8 Mpc, the transient was discovered on MJD = 59246.47 (2021-02-01.47) with an absolute magnitude of M = -11.07 +/- 0.18. The last non-detection through forced photometry was on MJD = 59238.56. Spectroscopic classification is encouraged.

ATLAS is a twin 0.5m telescope system on Haleakala and Mauna Loa which is robotically surveying the sky above declination -40 with a cadence of 2 days (Tonry et al. 2018, PASP,130:064505). Two filters are used, cyan and orange (denoted c and o; all mags quoted are in the AB system). While carrying out the primary mission for Near Earth Objects, we search for and publicly report stationary transients to the IAU Transient Name Server.  Data processing is carried out at Queen's University which combines automated source parameter filtering, machine learning image recognition, and spatial cross-matching with astronomical catalogues (Smith et al. 2020, PASP, 132:085002). More information is on the ATLAS homepage. We are submitting AstroNotes for transients that are either within 100 Mpc, or have some other interesting feature to bring to the community's attention, such as bright nuclear transients, slowly rising or rapidly fading objects.

We report a new transient source, possibly a nova, LBV, LRN, ILRT or young/reddened supernova in the galaxy UGC 05829. We discovered ATLAS21dic (AT2021blu) on MJD 59246.47 == 2021-02-01.47, at m_o = 18.49 +/- 0.18. There was no detection by ATLAS on MJD 59238.56 == 2021-01-24.56. ATLAS21dic is offset by 41.8 arcsec south, 101.6 arcsec west from UGC0 5829, which is at z = 0.002 or d = 8 Mpc (from NED), implying an absolute magnitude of M = -11.07 (assuming m-M = 29.51 and A_r = 0.05 and A_i = 0.04). The Pan-STARRS gri-band finder shows a faint, extended uncatalogued source at the transient position. This could be a background galaxy (and hence the transient may be background) or a starforming region of UGC 05829. Followup observations are encouraged.

The Asteroid Terrestrial-impact Last Alert System (ATLAS) project is primarily funded to search for near earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogs from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889, and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen's University Belfast, the Space Telescope Science Institute, the South African Astronomical Observatory, and The Millennium Institute of Astrophysics (MAS), Chile. 

Show current TNS values
Catalog Name Reported RA Reported DEC Reported Obj-Type Reported Redshift Host Name Host Redshift Remarks TNS RA TNS DEC TNS Obj-Type TNS Redshift
TNS 2021blu [ATLAS21dic] 10:42:34.338 +34:26:15.00 UGC 05829 0.002098 10:42:34.340 +34:26:14.60 LBV 0.002

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