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GCN Circular 34556

Subject
Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
Date
2023-08-25T21:25:27Z (8 months ago)
From
Dylan Dutton at UNC Chapel Hill <ddutton59@gmail.com>
Via
Web form
Dylan Dutton, Daniel Reichart, Joshua Haislip, Vladimir Kouprianov, Daryl Janzen, Arie Verveer, John Kennewell, Megan Dubay, Ruide Fu, Logan Selph, and Donovan Schlekat report on behalf of the Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill.

We observed the field of Swift J1727.8-1613  (GRB 230824A) (Page et al., GCN 34537; Navaneeth et al., GCN 34538, Odeh et al., GCN 34543) with our 0.4m robotic telecope located in Meckering, Australia. The observation began at 14:11:20 UTC on Aug 24 2023, approximately 11 minutes after the first trigger.

We obtained multiple expsoures in the B, V, R, and I filters. Exposure lengths were calculated using our automated exposure length scaling model.

We detected a bright object, in the same location as Odeh et al., GCN 34543, within the uncertainty radius of the Swift localization, at:
R.A. (J2000): 17:27:43.34
Dec. (J2000): -16:12:19.161

Below, we report our photometric measurements.
-------------------------------------------
Date TimeTakenUTC ExpTime Filter Mag MagErr
-------------------------------------------
08-24-2023 | 14:11:20 | 25.721s	| B | 14.22 | 0.013
08-24-2023 | 14:11:52 | 28.873s	| V | 13.88 | 0.011
08-24-2023 | 14:12:29 | 13.756s	| R | 13.69 | 0.012
08-24-2023 | 14:12:49 | 10.774s	| I | 13.60 | 0.014
08-24-2023 | 14:15:50 | 37.756s	| B | 14.25 | 0.010
08-24-2023 | 14:16:34 | 40.014s	| V | 13.89 | 0.008
08-24-2023 | 14:17:21 | 19.012s	| R | 13.69 | 0.009
08-24-2023 | 14:17:46 | 15.507s	| I | 13.67 | 0.012
08-24-2023 | 14:21:35 | 56.372s	| V | 13.89 | 0.007
08-24-2023 | 14:25:40 | 63.628s	| B | 14.26 | 0.007
08-24-2023 | 14:26:49 | 66.016s	| V | 13.88 | 0.006
08-24-2023 | 14:28:02 | 31.063s	| R | 13.64 | 0.006
08-24-2023 | 14:28:40 | 24.327s	| I | 13.60 | 0.008
08-24-2023 | 14:33:49 | 84.567s	| B | 14.25 | 0.006
08-24-2023 | 14:35:19 | 88.210s	| V | 13.86 | 0.005
08-24-2023 | 14:36:53 | 40.934s	| R | 13.65 | 0.005
08-24-2023 | 14:37:40 | 32.058s	| I | 13.63 | 0.007
08-24-2023 | 14:43:26 | 109.523s | B | 14.25 | 0.006
08-24-2023 | 14:45:23 | 113.289s | V | 13.89 | 0.005
08-24-2023 | 14:47:22 | 51.216s	| R | 13.67 | 0.005
08-24-2023 | 14:48:20 | 41.685s	| I | 13.61 | 0.007
08-24-2023 | 14:54:51 | 140.854s | B | 14.25 | 0.006
08-24-2023 | 14:57:17 | 147.908s | V | 13.88 | 0.005
08-24-2023 | 14:59:52 | 65.83s | R | 13.65 | 0.006
08-24-2023 | 15:01:05 | 53.273s	| I | 13.58 | 0.007
08-24-2023 | 15:09:40 | 177.571s | B | 14.15 | 0.005
08-24-2023 | 15:15:54 | 83.812s	| R | 13.65 | 0.006
08-24-2023 | 15:17:25 | 67.06s | I | 13.56 | 0.006
08-24-2023 | 15:27:51 | 225.946s | B | 14.23 | 0.006
08-24-2023 | 15:31:42 | 232.571s | V | 13.86 | 0.006
08-24-2023 | 15:35:41 | 105.216s | R | 13.61 | 0.006
08-24-2023 | 15:37:32 | 82.401s	| I | 13.60 | 0.007
08-24-2023 | 15:50:16 | 284.651s | B | 14.31 | 0.006
08-24-2023 | 15:55:06 | 293.376s | V | 13.81 | 0.004
08-24-2023 | 16:00:07 | 131.78s	| R | 13.57 | 0.005
08-24-2023 | 16:02:25 | 106.593s | I | 13.51 | 0.005
08-24-2023 | 16:30:17 | 164.791s | R | 13.53 | 0.006
08-24-2023 | 16:33:08 | 133.318s | I | 13.50 | 0.009

Our images have been calibrated using stars from the APASS catalog.
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