GCN Circular 18552
Subject
GRB 151027A: Correction to GCN 18519
Event
Date
2015-11-02T19:12:53Z (10 years ago)
From
Zach Cano at U of Iceland <zewcano@gmail.com>
���Z. Cano (U. Iceland) reports on behalf of a larger collaboration:
Upon further investigation, it was discovered that the magnitudes given in
GCN Circ. 18519 are incorrect. The presented photometry was not for the
optical and NIR afterglow of GRB 151027A, but rather the fainter object
that is 3.1 arcsec SW of the afterglow (Dichiara et al. GCN Circ. 18510).
A revised summary of the NOT observations follows:
Filter t-t0 (hr) Mag +- Merr
-----------------------------------------
B 17.94 18.2 +- 0.1
R 18.17 17.9 +- 0.1
I 18.28 17.4 +- 0.1
J 16.92 16.4 +- 0.1
H 17.38 15.5 +- 0.1
K 17.60 15.1 +- 0.1
The optical filters are calibrated to USNO-B1 and the NIR filters to 2MASS,
where a single star that appears in both catalogs was used for the
zeropoint calculation. These magnitudes are not corrected for foreground
extinction.
When these extinguished magnitudes are converted to monochromatic fluxes
(using the zeropoints from Fukugita et al. 1995; Hewett et al. 2006), a
single power-law with an exponent of -0.8 provides a good fit to the
optical-to-NIR spectral energy distribution.
My apologies for the confusion.���