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GCN Circular 28175

Subject
GRB 200729A: HST imaging
Date
2020-07-30T04:27:51Z (4 years ago)
From
Gagandeep S. Anand at University of Hawaii <gsanand@hawaii.edu>
G. S. Anand (Hawaii), R. B. Tully (Hawaii), L. Rizzi (Keck), I.
Karachentsev (Special Astrophysical Observatory, Russia), E. Shaya (UMD)

On 2020-07-15 12:14:59, we obtained Hubble Space Telescope imaging of NGC
4242 as part of the Every Known Nearby Galaxy survey (SNAP-15922, PI R.
Tully). Our data consists of imaging in F606W (760s) and F814W (760s)
bands, which cover the localized region from Swift of GRB 200729A.

Our observations show an extended red source within the 1.7" Swift
localization region, which may be a background galaxy.  DOLPHOT PSF
photometry shows several point sources within the 1.7" region as well, with
the two brightest point sources having (F606W, F814W) magnitudes of
(23.556, 23.509) and (26.182, 23.833). In our deep CMD, the observed
location of the TRGB suggests a distance of ~7.5 Mpc, further than previous
TRGB determinations of 5.3 Mpc (Sabbi et al. 2018, ApJS, 235, 23).

Link to color HST image, with background galaxy manually highlighted in red
circle:
https://gsanand.github.io/ngc4242.jpg
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