AstroNote 2020-175

Primary tabs

DRAFT
2020-09-13 21:00:22
Type: Object/s-Discovery/Classification
ATLAS discoveries of four young transients within 100 Mpc
Authors: M. Fulton, K. W. Smith, S. Srivastav, O. McBrien, S. J. Smartt, J. Gillanders, P. Clark, D. O'Neill, D. R. Young, 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 discoveries of four young transients: ATLAS20znd (AT2020szq) in galaxy LEDA 1897886. At a distance of 76 Mpc, ATLAS20znd was discovered on MJD = 59103.59 (2020-09-11.59) with a magnitude m_o = 18.04 +/- 0.11 hence an absolute magnitude of M = -17.6 +/- 0.19. ATLAS20zne (AT2020szr) in galaxy UGC 12395. At a distance of 95 Mpc, ATLAS20zne was discovered on MJD = 59103.46 (2020-09-11.46) with a magnitude m_o = 18.73 +/- 0.09 hence an absolute magnitude of M = -16.5 +/- 0.17. ATLAS20znf (AT2020szs) in galaxy CGCG 402-005. At a distance of 88 Mpc, ATLAS20znf was discovered on MJD = 59103.40 (2020-09-11.40) with a magnitude m_c = 18.43 +/- 0.11 hence an absolute magnitude of M = -16.4 +/- 0.19. ATLAS20znh (AT2020szt) in galaxy MCG-05-04-040. At a distance of 84 Mpc, ATLAS20znh was discovered on MJD = 59103.49 (2020-09-11.49) with a magnitude m_o = 19.07 +/- 0.18 hence an absolute magnitude of M = -15.6 +/- 0.23. Spectroscopic classifications are 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 four new transient sources, most likely young supernovae.

In galaxy LEDA 1897886 we discovered ATLAS20znd (AT2020szq) on MJD 59103.59 == 2020-09-11.59 at m_o = 18.04 +/- 0.11. The last non-detection through forced photometry was on MJD 59097.58 == 2020-09-05.58. ATLAS20znd is offset by 1.3 arcsec South, 1.1 arcsec West from the likely host galaxy LEDA 1897886, which is at z = 0.019 or d = 76 Mpc (from NED), implying an absolute magnitude of M = -17.6 (assuming m-M = 34.40 and A_r = 1.44 and A_i = 1.07).

In galaxy UGC 12395 we discovered ATLAS20zne (AT2020szr) on MJD 59103.46 == 2020-09-11.46 at m_o = 18.73 +/- 0.09. The last non-detection through forced photometry was on MJD 59098.51 == 2020-09-06.51. ATLAS20zne is offset by 16.2 arcsec North, 19.6 arcsec West from the likely host galaxy UGC 12395, which is at z = 0.025 or d = 95 Mpc (from NED), implying an absolute magnitude of M = -16.5 (assuming m-M = 34.88 and A_r = 0.41 and A_i = 0.31).

In galaxy CGCG 402-005 we discovered ATLAS20znf (AT2020szs) on MJD 59103.40 == 2020-09-11.40 at m_c = 18.43 +/- 0.11. The last non-detection through forced photometry was on MJD 59102.40 == 2020-09-10.40. ATLAS20zne is offset by 3.5 arcsec North, 4.4 arcsec West from the likely host galaxy CGCG 402-005, which is at z = 0.022 or d = 88 Mpc (from NED), implying an absolute magnitude of M = -16.4 (assuming m-M = 34.71 and A_r = 0.09 and A_i = 0.07).

In galaxy MCG -05-04-040 we discovered ATLAS20znh (AT2020szt) on MJD 59103.49 == 2020-09-11.49 at m_o = 19.07 +/- 0.18. The last non-detection through forced photometry was on MJD 59097.46 == 2020-09-05.46. ATLAS20znh is offset by 5.4 arcsec North, 7.4 arcsec West from the likely host galaxy MCG-05-04-040, which is at z = 0.021 or d = 84 Mpc (from NED), implying an absolute magnitude of M = -15.6 (assuming m-M = 34.62 and A_r = 0.09 and A_i = 0.06).

Follow-up observations and spectroscopic classifications of these transients are encouraged.

This work has made use of data from the Asteroid Terrestrial-impact Last Alert System (ATLAS) project. ATLAS is primarily funded to search for Near-Earth asteroids through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogues from the survey area.  The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen's University Belfast, and the Space Telescope Science Institute.

Show current TNS values
CatalogNameReported RAReported DECReported Obj-TypeReported RedshiftHost NameHost RedshiftRemarksTNS RATNS DECTNS Obj-TypeTNS Redshift
TNS2020szq [ATLAS20znd]04:07:24.073+30:17:19.80LEDA 18978860.01855304:07:24.057+30:17:19.47
TNS2020szr [ATLAS20zne]23:09:33.094+15:39:33.38UGC 123950.02528123:09:33.100+15:39:33.43SN Ia0.02581
TNS2020szs [ATLAS20znf]21:34:09.011+08:46:46.86CGCG 402-0050.02212521:34:08.994+08:46:46.20SN II0.022125
TNS2020szt [ATLAS20znh]01:28:54.688-32:00:51.61MCG -05-04-0400.02093801:28:54.688-32:00:51.61