TITLE: GCN CIRCULAR NUMBER: 15878 SUBJECT: GRB 140219A: iPTF optical observations DATE: 14/02/23 02:36:37 GMT FROM: Leo Singer at CIT/PTF L. P. Singer (Caltech), M. M. Kasliwal (Carnegie Observatories/Princeton), and S. B. Cenko (NASA/GSFC) report on behalf of the intermediate Palomar Transient Factory (iPTF) collaboration: We have searched for optical counterparts of GRB 140219A using the Palomar 48-inch Oschin telescope (P48). We observed 9 fields covering an area of 67.8 deg2 intersecting the Fermi GBM 1-sigma contour (Fermi trigger 414531995, Zhang et al., GCN 15866) and a preliminary MESSENGER-Suzaku IPN annulus (K. Hurley, personal communication) that was available when the GBM localization was first observable from Palomar. We observed all 9 fields for several epochs, with the first epoch extending from 7.0 to 8.1 hours after the burst. Sifting through candidate variable sources using image subtraction and standard iPTF vetting procedures, we found no compelling optical afterglow candidates to an average limiting magnitude of r=21.1 mag. About 80% of the published IPN error box (Hurley et al., GCN 15864) was contained in these 9 fields, with most of the remaining 20% falling on a disabled CCD on the P48. To fill the gap in the IPN error box, we observed two additional fields starting 33.7 hours after the burst. The deepest epoch of observations of these two fields had a limiting magnitude of r=20.7 mag. Since we lacked reference images for these two offset fields, we performed a catalog comparison search, examining any source that was detected in our two deepest epochs but was not coincident with a stellar object in SDSS. Of 342 sources meeting this criterion, all were known galaxies and none were compelling optical afterglow candidates. XRT source 1 (http://www.swift.ac.uk/xrt_products/TILED_GRB00024/index_1.php, Mangano et al., GCN 15872) is contained in our nine early fields, and we associate a coincident optical detection with the star SDSS J102559.46+073114.1. XRT source 2 (http://www.swift.ac.uk/xrt_products/TILED_GRB00024/index_2.php, Mangano et al., GCN 15872) is contained in our two late fields, and we detect no coincident optical source to a limiting magnitude of r=20.5 mag at 35.7 hours after the burst. XRT source 4 (http://www.swift.ac.uk/xrt_products/TILED_GRB00024/index_4.php) is contained in our nine early fields, and we find no coincident optical source to a limiting magnitude of r=20.2 mag at 8.1 hours after the burst. XRT source 5 (http://www.swift.ac.uk/xrt_products/TILED_GRB00024/index_5.php, Mangano et al., GCN 15875), the most plausible afterglow candidate due to its observed fading, is also contained in our two late fields. We detect two optical sources within the XRT error circle: the star SDSS J102406.41+062937.6, and the galaxy SDSS J102406.58+062945.7. These were also the sources detected by Pozanenko et al. (GCN 15876). For the star, we report r=20.0+/-0.1, which is about 0.5 mag brighter than the value given by SDSS DR10. We find no additional sources inside the XRT error circle to a limiting magnitude of r=21.0. The diagram http://www.its.caltech.edu/~lsinger/iptf/Fermi414531995.pdf shows the footprints of the nine early P48 fields in relation to the Fermi GBM 1-, 2-, and 3-sigma statistical+systematic contours (black) and the IPN INTEGRAL-MESSENGER and WAM-HEND annuli (blue). The INTEGRAL-MESSENGER annulus is comparable to the initial MESSENGER-Suzaku localization on which we based these observations. The diagram http://www.its.caltech.edu/~lsinger/iptf/Fermi414531995_inset_1.pdf shows the early P48 fields in relation to a six-sided IPN polygon and the XRT candidates. The diagram http://www.its.caltech.edu/~lsinger/iptf/Fermi414531995_inset_2.pdf shows the late P48 fields.