GRB 190406B

Authors: Tomas Ahumada (UMD), S. Bradley Cenko (NASA GSFC), Michael W.
Coughlin (Caltech), Eric C. Bellm (UW), Leo P. Singer (NASA GSFC), Shaon
Ghosh (UWM), Mansi M. Kasliwal (Caltech), Shreya Anand (Caltech), Igor
Andreoni (Caltech), Scott Adams (Caltech), Matt Hankins (Caltech), Varun
Bhalerao (IITB), Harsh Kumar (IITB), V. Zach Golkhou (UW) on behalf of the
ZTF and GROWTH collaborations and the KPED team

We observed the localization region of the short GRB190406B (trigger
576241792) detected by the Gamma-Ray Burst Monitor (GBM) on the Fermi
satellite with the Palomar 48 inch telescope equipped with the 47 square
degree Zwicky Transient Facility (ZTF) camera. We obtained a series of r-
and g-band images covering 268 square degrees beginning at 08:01 UT on 2019
April 08 (44:52 hours after the burst trigger time). This corresponds to ~
44% of the probability enclosed in the intersection of the GBM and IPN
localization regions. We revisited the region on 2019 April 11, starting at
08:03 UT (116:54 hours after the burst trigger time) and we covered the
same ~ 44% of the probability region.

The images were processed through the ZTF reduction and image subtraction
pipelines at IPAC to search for potential counterparts. 240
high-significance transient and variable candidates were identified by our
pipeline in the area observed, 236 of which had previous detections with
ZTF in the days and weeks prior to the GRB trigger time (e.g., supernovae,
active galactic nuclei).

Further follow-up of 4 transients was obtained with the Kitt Peak EMCCD
Demonstrator (KPED) on the Kitt Peak 84-inch telescope on April 12.
Additionally, we obtained follow-up spectroscopy of 2 candidates with the
Double Spectrograph (DBSP) on Palomar 200��� the nights of April 12. The
candidates are listed below, however no photometric evolution or spectral
classification was consistent with an optical counterpart.

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       ZTF ID            RA DEC         last non-detection discovery   KPED
Class

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                                 deg deg date in 2019       April 08 April
12

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ZTF19aapgbri    275.504094 +55.964483    04-07 r<20.41    g = 21.36
  g=20.76        SN Ia
ZTF19aapgdcn  285.158686 +69.881810     04-04 r<19.49    g = 20.67   g=21.74
       SN Ia

ZTF19aapfxqv     276.915046 +65.626121    04-04 r<17.61    g=20.67
  g=20.67    SN*

ZTF19aapwbgo   278.519641 +57.057325    04-07 r<20.35    g=21.61   g=22.36
   SN*

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*Classification from photometric data points.


The median 5 sigma upper limit for an isolated point source in our images
was r > 21.5 and g > 21.8 mag for the observations made on April 8 26 and r
> 21.9 and g > 21.6 mag for the observations made on April 11.

ZTF is a project led by PI S. R. Kulkarni at Caltech (see ATEL #11266
<http://www.astronomerstelegram.org/?read=11266>), and includes IPAC; WIS,
Israel; OKC, Sweden; JSI/UMd, USA; UW, USA; DESY, Germany; NRC, Taiwan; UW
Milwaukee, USA and LANL USA. ZTF acknowledges the generous support of the
NSF under AST MSIP Grant No 1440341. Alert distribution service provided by
DIRAC@UW. Alert filtering is being undertaken by the GROWTH marshal system,
supported by NSF PIRE grant 1545949.

V. Lipunov, E. Gorbovskoy, N.Tyurina, V.Kornilov, D.Vlasenko, V.Vladimirov, D.Zimnukhov,
A.Kuznetsov, P.Balanutsa, A. Chasovnikov, V.Topolev, D.Kuvshinov, F.Balakin (Lomonosov Moscow State University, SAI, Physics Department),

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres (The Instituto de Astrofisica de Canarias),

D. Buckley (South African Astronomical Observatory),

O. Gress, N.M. Budnev, O.Ershova (Applied Physics Institute, Irkutsk State University),

V. Yurkov, A. Gabovich, Yu. Sergienko, D. Kobcev (Blagoveschensk Educational State University),


A. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),

R. Podesta, C. Lopez, C.Francile, F. Podesta (Observatorio Astronomico Felix Aguilar OAFA, San Juan National University),

H.Levato (Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE SJNU)

MASTER Global Robotic Net (http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, v. 2010, 30L)
automatically started inspection of  Fermi trigger 576241792 https://gcn.gsfc.nasa.gov/other/576241792.fermi
7843s after trigger time at 2019-04-06  13:20:30 UT

MASTER Net cover map is available at http://observ.pereplet.ru/images/MASTER_FermiTrig576241792covermap.jpg

MASTER-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University)
was pointed to the  FERMI GRB190406.47 ( 19h  5m 21.60s , +61d 30m 00.00s, R=7.09)
7843 sec after trigger time at 2019-04-06 13:20:30 UT, with upper limit up to  19.8 mag.
Observations started at twilight.  The observations began at zenit distance = 65 deg. The sun  altitude  is -14.6 deg.

MASTER-Kislovodsk robotic telescope  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory)
started FERMI GRB190406.47 / trigger 576241792 inspection  20777 sec after trigger time at 2019-04-06 16:56:04 UT, 
with upper limit up to  19.9 mag. Observations started at twilight.
  The observations began at zenit distance = 74 deg. The sun  altitude  is -13.8 deg.

MASTER-Tavrida robotic telescope  located in Russia (Lomonosov MSU, SAI Crimea astronomical station)
started FERMI GRB190406.47 inspection 26157 sec after trigger time at 2019-04-06 18:25:44 UT, with upper limit up to  19.5 mag.
The observations began at zenit distance = 70 deg. The sun  altitude  is -22.5 deg.

MASTER-IAC robotic telescope  located in Spain (IAC Teide Observatory) started
  FERMI GRB190406.47 inspection 39426 sec after trigger time at 2019-04-06 22:06:53 UT, with upper limit up to  20.1 mag.
The observations began at zenit distance = 84 deg. The sun  altitude  is -34.8 deg.

The galactic latitude b = -60 deg., longitude l = 98 deg.


MASTER auto-detection system didn't find OT connected with GRB.

During inspection we find OT

MASTER OT J193011.47+465928.3 detection - preliminary dwarf nova outburst, ampl>4.3m

MASTER-Kislovodsk auto-detection system (Lipunov et al., 2010, Advances in Astronomy, v. 2010, 30L)
discovered OT source at (RA, Dec) = 19h 30m 11.47s +46d 59m 28.3s on 2019-04-07.95397 UT.
The OT unfiltered magnitude is 15.4m (limit 19.0m).

The OT is seen in 8 images. There is no minor planet at this place.

We have reference image without OT on 2019-02-13.08602 UT with unfiltered 
magnitude limit 19.6m, on 2016-07-29 21:12:44 with mlim=19.7, it means 
more then 4.3m of current outburst amplitude (there is USNO-B1 star in 0.3" with B1=19.5,R2=19.3).

Spectral observations are required.

The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/193011.47465928.3.png

We checked coordinates of 4 ZTF candidates (Ahumada et al. GCN24130
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 ) in 
MASTER database  and didn't find OT at position of 3 ones since 2009y (up to unfiltered 20.0)

About ZTF19aapfxqv
MASTER has seen an object at the position 
18h 27m 39.96s , +65d 37m 33.70s (MASTER OT J182739.96+653733.70) 
on 2017-12-07 21:15:28.334UT with m_OT=18.3+-0.2 (and we should note there 
is PanSTARRs source in 5.7").

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