GRB 190530A
GCN Circular 24978
Subject
GRB 190530A: Observation of the afterglow by NOEMA
Date
2019-07-04T15:22:54Z (6 years ago)
From
Antonio de Ugarte Postigo at IAA-CSIC <deugarte@iaa.es>
A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), M. Bremer (IRAM),
S. Schulze (Weizmann), C. C. Thoene, D. A. Kann, L. Izzo, M. Blazek,
K. Bensch (all HETH/IAA-CSIC), D. A. Perley (LJMU), S. Martin (ALMA),
I. de Gregorio-Monsalvo (ESO), M. Michalowski (AOI-AMU),
R. Sanchez-Ramirez (INAF-IAPS), D. B. Malesani (DTU Space) report:
We observed the field of the bright GRB 190530A (Fermi team GCN
24676) with NOEMA, at wavelengths between 76 and 150 GHz in 4
epochs, ranging between 31 May 2019, at 14:29 UT (1.17 days after the
burst) and 15 June 2019, at 20:54 UT (16.44 days after the burst). The
afterglow (discovered in the optical by Lipunov et al. GCN 24680) was
detected on the first epoch with a flux density of 1.0 mJy at 92 GHz. At
this time the peak frequency was located close to this observed frequency.
In the subsequent epochs the peak frequency of the synchrotron spectrum
was bluewards of the 76 GHz frequency band and the source declined
steadily in flux density until it was no longer detected in our latest
observation, which had an r.m.s of 0.066 mJy at the 92 GHz band.
GCN Circular 24763
Subject
GRB 190530A: Further OAJ/OSN photometry and analysis
Date
2019-06-06T16:58:21Z (6 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC,
DARK/NBI), L. Izzo, M. Blazek, C. C. Thoene, K. Bensch (all
HETH/IAA-CSIC) report:
We checked the magnitude of our second-epoch OSN observation (Kann et
al., GCN 24700) of the Fermi GBM/LAT GRB 190530A (Fermi GBM team, GCN
24676; Longo et al., GCN 24679) and found a calculation error which
resulted in an incorrect zero-point. Remeasuring the magnitude against
four SDSS stars (once again transformed to Rc via the equations of
Lupton 2005) we now derive Rc(AB) = 19.51 +/- 0.04 mag. This is in good
agreement with the value obtained by Moskvitin & Uklein (GCN 24708). The
magnitude of Belkin et al. (GCN 24698) is still overly bright compared
to our new result, and the revised value from Vinko et al. (GCN 24751)
is now significantly fainter.
We obtained 7 x 300 s images in SDSS r' with the 0.8m telescope of the
Observatorio Astrofisico de Javalambre (Teruel, Spain). The first three
images were taken too early in twilight and were discarded. The
afterglow is clearly detected in the stack of the four last images, and
we measure:
r'(AB) = 20.27 +/- 0.06 mag at 2.43735 days after the GRB.
This is in good agreement with an earlier value from Vinko et al. (GCN
24751) combined with a steep decay.
Using the further photometry published since Kann et al. (GCN 24700)
(Moskvitin et al., GCN 24708; Belkin et al., GCN 24712; Kumar et al.,
GCN 24729; Nandi et al., GCN 24745; Vinko et al., GCN 24751) we find:
- The steep decay between the observation of Watson et al. (GCN 24690)
and Xin et al. (GCN 24697) remains, and is not significantly affected by
our revised OSN measurement.
- There may be a small flare at 1.4 days (this GCN [OSN]; Moskvitin et
al., GCN 24708).
- Starting at 2.2 days (Belkin et al., GCN 24712; Vinko et al., GCN
24751; this GCN [OAJ]; Nandi et al., GCN 24745