Difference: GCNCIRCULAR20799 ( vs. 1)

P. Garnavich (Notre Dame)

We obtained near-infrared H-band imaging of a possible IR counterpart to the gamma-ray burst AGL J1914+1043 (Yoshida et. al GCN 20784; Tavani et al. GCN 20754). Data was taken on 2017 March 2.55 (UT) using the LUCI imaging/spectrographs on the Large Binocular Telescope. Ten dithers each with 6x10s exposures were taken through the H filter in 0.7 arcsec seeing.

The IR variable discovered by Yoshida et al. (GCN 20784) is clearly visible in the crowded, heavily reddened field. Using nearby 2MASS stars, we estimate the brightness of the variable source to be H=15.01+/-0.06 mag.

We measure the position of the IR variable to be RA=19:10:31.49 DEC=+7:53:52.25 in the 2MASS coordinate system with an uncertainty of 0.12 arcsec.

Converting the Yoshida et al. AB mag to the 2MASS system means the source brightness was H=14.9 mag on February 27 (UT). Given the uncertainties in converting between systems and filters, the source has been relatively constant over three days. Therefore, it is not clear that this is the IR counterpart to AGL J1914+1043.

We note that the UKIDSS-DR6 detected an extremely red object within 0.1 arcsec of the variable with a magnitude of H=17.4 mag (Vega). This suggests that a faint source was present during the UKIDSS survey and has since brightened by 2.4 mag in H-band.

We thank Dave Thompson (LBTO), Jonathan Brown, and Jiayi Sun (OSU) for making these obervations with the LBT.

-- ThomasKupfer - 02 Mar 2017