TITLE:   GCN CIRCULAR
NUMBER:  36097
SUBJECT: GRB 240414A: Skynet Optical Afterglow Observations
DATE:    24/04/14 18:19:53 GMT
FROM:    Dylan Dutton at UNC Chapel Hill <ddutton59@gmail.com>

Dylan Dutton, Megan Dubay, Ruide Fu, Donovan Schlekat, Daniel Reichart, Joshua Haislip, Vladimir Kouprianov, Daniel Caton, Lee Hawkins, Dean Glace, Daryl Janzen, Kim Janzen, James Davidson, Edward Murphy, and Carlos Salgado report on behalf of the Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill.

We observed the field of GRB 240414A with three of our North American robotic telescopes. The first detection occurred at 02:36:17 UTC on Apr 14 2024, approximately 15 minutes after the trigger reported by Swift (Caputo et al., GCN 36083).

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

We detect the optical afterglow with coordinates consistent to those reported by OHP/T193 (B. Schneider et al., GCN 36084).

The coordinates are:
R.A. (J2000): 12:19:08.12
Dec. (J2000): 56:44:28.70

We report the photometry below. We estimate a temporal index of about -0.9 and spectral index of about -0.5.

ExpLen | Filter | Mag   | Mag Error  | MJD         
------------------------------------------------
51.99  | B      | 17.02 | 0.066      | 60414.108
52.82  | V      | 16.92 | 0.068      | 60414.110
27.18  | R      | 16.46 | 0.086      | 60414.111
76.20  | V      | 17.77 | 0.122      | 60414.115
38.54  | R      | 17.02 | 0.117      | 60414.117
103.4  | B      | 17.86 | 0.096      | 60414.120
52.39  | R      | 17.26 | 0.117      | 60414.124
138.1  | V      | 17.45 | 0.084      | 60414.128
63.67  | R      | 17.13 | 0.117      | 60414.130
300    | R      | 18.77 | 0.116      | 60414.204
300    | R      | 18.61 | 0.101      | 60414.207
300    | V      | 19.04 | 0.064      | 60414.208
300    | V      | 19.03 | 0.063      | 60414.208
300    | R      | 18.89 | 0.126      | 60414.211
300    | V      | 18.85 | 0.054      | 60414.211
300    | V      | 18.85 | 0.054      | 60414.211
300    | R      | 18.54 | 0.091      | 60414.214
300    | V      | 18.97 | 0.059      | 60414.215
300    | V      | 18.98 | 0.059      | 60414.215
300    | R      | 18.92 | 0.134      | 60414.218
300    | V      | 19.03 | 0.063      | 60414.218
300    | V      | 19.03 | 0.063      | 60414.218
300    | R      | 18.94 | 0.138      | 60414.221
300    | V      | 19.03 | 0.062      | 60414.222
300    | V      | 19.04 | 0.062      | 60414.222
300    | R      | 18.67 | 0.106      | 60414.225
300    | V      | 19.12 | 0.065      | 60414.225
300    | V      | 19.05 | 0.061      | 60414.225
300    | R      | 18.67 | 0.106      | 60414.228
300    | V      | 19.15 | 0.070      | 60414.229
300    | V      | 19.16 | 0.070      | 60414.229
300    | R      | 18.96 | 0.137      | 60414.232
300    | V      | 19.16 | 0.069      | 60414.233
300    | V      | 19.20 | 0.072      | 60414.233
300    | R      | 18.72 | 0.113      | 60414.236
300    | V      | 19.30 | 0.076      | 60414.236
300    | V      | 19.29 | 0.075      | 60414.236
300    | V      | 19.16 | 0.071      | 60414.240
300    | V      | 19.21 | 0.075      | 60414.240
300x3  | R      | 19.02 | 0.138      | 60414.243
300x3  | R      | 19.26 | 0.090      | 60414.295
300x3  | R      | 19.22 | 0.088      | 60414.306
300x3  | R      | 19.35 | 0.080      | 60414.316
300x3  | R      | 19.54 | 0.092      | 60414.327
300x3  | R      | 19.35 | 0.159      | 60414.337
300x5  | R      | 19.59 | 0.147      | 60414.351

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