AstroNote 2020-121

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DRAFT
2020-06-19 18:23:45
Type: Object/s-Discovery/Classification
Pan-STARRS Search for Kilonovae: discovery of two intrinsically faint transients within 200 Mpc
Authors: M. Fulton, S. J. Smartt, K. W. Smith (QUB), K. C. Chambers, M. Huber (IfA, Hawaii), S. Srivastav, O. McBrien, D. R. Young, J. Gillanders, D. O'Neill, P. Clark, S. Sim (QUB), T. de Boer, J. Bulger, J. Fairlamb, C.-C. Lin, T. Lowe, E. Magnier, A. Schultz, R. J. Wainscoat, M. Willman (IfA), T.-W. Chen (Stockholm), D. E. Wright (University of Minnesota), C. Stubbs (Harvard), A. Rest (STScI)
Source Group: Pan-STARRS1
Abstract:
We are carrying out the "Pan-STARRS Search for Kilonovae" which is a focused search for intrinsically faint transients, or rapidly evolving transients in galaxies which are closer than 200 Mpc in the ongoing Pan-STARRS Near-Earth Object surveys (see Smartt et al. AstroNote 2019-48 for details).  Here we report the discovery of two intrinsically faint transients; PS20ehq (AT2020mvi) and PS20eid (AT2020myv). PS20ehq is associated with host galaxy WISEA J210229.83-092340.0, at a redshift of z = 0.036 or d = 151 Mpc (from NED). Its discovery magnitude (MJD = 59015.53) is w = 21.01 +/- 0.21, and hence an absolute magnitude of M_w = -15.0 +/- 0.3. PS20eid is associated with host galaxy WISEA J130016.32-170138.3, at a redshift of z = 0.016 or d = 77 Mpc (from NED). Its discovery magnitude (MJD = 59016.27) is w = 19.43 +/- 0.10, and hence an absolute magnitude of M_w = -15.2 +/- 0.2.

We are carrying out the "Pan-STARRS Search for Kilonovae" which is a focused search for intrinsically faint transients, or rapidly evolving transients in galaxies which are closer than 200 Mpc in the ongoing Pan-STARRS Near-Earth Object surveys (see Smartt et al. AstroNote 2019-48 for details). 

In normal survey mode, Pan-STARRS takes 4 x 45s exposures in w, i or z each night reaching 5 sigma magnitudes of w<22, i<21 and z<20.5 in each frame (see Chambers et al. 2016, 1612.05560). 

Here we report the discovery of two intrinsically faint transients; PS20ehq (AT2020mvi) and PS20eid (AT2020myv). PS20ehq is associated with host galaxy WISEA J210229.83-092340.0, at a redshift of z = 0.036 or d = 151 Mpc (from NED). The transient was discovered on MJD 59015.53 (2020-06-15.53) at mag m_w = 21.01 +/- 0.21. It is offset from the host by 3.1" S, 3.0" E (a projected 3.2 kpc radius from the galaxy centre). At this distance the absolute magnitude is M_w = -15.0 (assuming m-M = 35.89 and foreground extinction of  A_w = 0.16). PS20eid is associated with host galaxy WISEA J130016.32-170138.3, at a redshift of z = 0.016 or d = 77 Mpc (from NED). The transient was discovered on MJD 59016.27 (2020-06-16.27) at mag m_w = 19.43 +/- 0.10. It is offset from the host by 7.1" S, 3.3" E (a projected 3.2 kpc radius from the galaxy centre). At this distance the absolute magnitude is M_w = -15.2 (assuming m-M = 34.43 and foreground extinction of  A_w = 0.15). A screenshot of the forced photometry for PS20eid is attached. Spectroscopic classification of both transients is encouraged. 

We will release AstroNotes for all these candidates and encourage spectroscopic classification or photometric follow-up. Finders are attached. 

These discoveries are a byproduct of the Pan-STARRS NEO survey observations supported by the NASA Grants, including No. NNX14AM74G issued through the SSO Near-Earth Object Observations Program.

Show current TNS values
CatalogNameReported RAReported DECReported Obj-TypeReported RedshiftHost NameHost RedshiftRemarksTNS RATNS DECTNS Obj-TypeTNS Redshift
TNS2020mvi [PS20ehq]21:02:30.045-09:23:42.83WISEA J210229.83-092340.00.03625821:02:30.039-09:23:42.67
TNS2020myv [PS20eid]13:00:16.546-17:01:45.20WISEA J130016.32-170138.30.01644813:00:16.540-17:01:45.23