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GCN Circular 34577

Swift J1727.8-1613 (GRB 230824A): Osservatorio Astronomico "Nastro Verde" optical observations
2023-08-27T19:24:18Z (9 months ago)
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <>
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Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), 
Y. Niino (Tokyo University, Institute of Astronomy), 
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
Following the Swift trigger no. 1186959 (GCN 34537), we pointed at the coordinates RA(J2000)=17h 27m 46s: Dec(J2000)=-16d 12' 53" and started our observations with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy.
Member of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
AstroCampania Associazione.

The observations started at 19:23 UT of 2023/08/24, after about 5,25 hours after the GRB trigger, at the end of twilight with clear skies, with principal telescope  SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME
I took 9 image of 120 sec each in fotometric V and 13 in Rc . All images, calibrated with masterdark and masterflat have been measured with Maxim DL software
We have detected a clear visible source at the enhanced position reported by Swift Burst Alert Telescope (BAT) (Page et al., GCN 34537 ) and by other telescopes ( Jamie A. Kennea (PSU) et al GCN 34540., S. Dichiara (PSU) et al GCN 34542, 34547, 34554,34555., Mohammad Odeh et al GCN 34543, 34561., H. Negoro (Nihon U). et al GCN 34544., Brendan O'Connor et al GCN 34549.,Dylan Dutton et al GCN 34556., T. M. Parsotan et al GCN 34557., U.Quadri et al GCN 34562., Claudio Lopresti et al GCN 34566., S. Leonini et al GCN 34573) 
at following position

RA (J2000.0)   17:27:43.32
Dec (J2000.0) -16:12:19

with the following photometry:

    JD	           Mag	        Filter
2460181.317	13.69            V
2460181.32	13.74            V
2460181.323	13.66            V
2460181.326	13.59            V
2460181.329	13.63            V
2460181.332	13.55            V
2460181.335	13.54            V
2460181.338	13.62            V
2460181.341	13.55            V

JD	          Mag	       Filter
2460181.309	13.49            Rc
2460181.31	13.51            Rc
2460181.312	13.54            Rc
2460181.313	13.45            Rc
2460181.315	13.47            Rc
2460181.318	13.48            Rc
2460181.321	13.50            Rc
2460181.324	13.52            Rc
2460181.33	13.45            Rc
2460181.333	13.46            Rc
2460181.336	13.50            Rc
2460181.339	13.50            Rc
2460181.342	13.50            Rc

The magnitudes are calibrated with stars of the PanSTARRS catalog, espressed in AB system and are not corrected for the expected Galactic extinction.

The peculiar transient ( detected by other observatories ) is confirmed in our observations. Further observations are encouraged.
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