TITLE:   GCN CIRCULAR
NUMBER:  37159
SUBJECT: GRB 240809A : RAPAS follow-up observations
DATE:    24/08/12 21:51:25 GMT
FROM:    Thierry Midavaine at GRANDMA <thierrymidavaine@sfr.fr>

Thierry Midavaine on behalf of the RAPAS network reports (#1) :

P. Martinez and C. Latgé [1], M. Serrau [2] and A. Leroy [3] observed the Gamma-Ray Burst GRB240809A (Evans et al. GCN 37110 ; Want et al. GCN 37113) using [1] ADAGIO N 820mm telescope at Belesta Observatory (IAU A05) equiped with a Moravian CMOS camera, [2] SC 300mm telescope at Vidauban [A77] equiped with a QHYCCD CMOS camera and [3] SC 350mm telescope at Madagascar equiped with a ZWO ASI CMOS camera. [1] and [2] are equiped with the set of 3 RAPAS filters meeting the Gaia G, Gbp and Grp photometric bands. The FITS files are reduced with the Gaia photometric catalog in respective spectral bands.

The afterglow is detected RA(J2000) = 5h 50m 10.55s ; Dec(J2000) = -02d 19' 03.3" [1]

MJD (mid)          Gaia filter band      mag.(Gaia)    RAPAS station

60531.66128        G                     19.75 ± 0.14  [3]
60531.86667        Grp                   20.48 ± 0.60  [1]
60531.86736        G                     20.52 ± 0.47  [2]
60531.87778        Gbp                   20.10 ± 0.32  [1]
60531.89444        G                     20.58 ± 0.19  [1]

RAPAS ( https://proam-gemini.fr/rapas/ ) is a new ProAm collaboration funded by Paris Observatory, delivering to a network of french amateur observatories a set of 3 filters meeting the Gaia spectral bands. This network is dedicated to deliver data in the Gaia photometric system on selected astrophysical alerts by Astro-COLIBRI ( https://astro-colibri.com/ ) or from Gaia alerts.