Skip to main content
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 36237

LIGO/Virgo/KAGRA S240422ed: MeerLICHT and BlackGEM observations report
2024-04-23T00:21:49Z (a month ago)
Paul Groot at Radboud University Nijmegen <>
legacy email
P.J. Groot (Radboud/UCT/SAAO), S. Bloemen (Radboud), D. Pieterse
(Radboud), H. Tranin (U Barcelona), I. Arcavi (TelAviv) and P. Vreeswijk
(Radboud) report on behalf of the BlackGEM/MeerLICHT consortium:

Following the LVK Alert S240422ed (GCN36235, GCN36236) the 0.6m
BlackGEM and MeerLICHT telescopes array, located at the ESO La Silla,
Chile and SAAO Sutherland, South Africa observatories, have started to
observe the error box with the ML1/BG2/BG4 telescopes using a
predefined sky-grid tiling that covers the accessible part of the
error region using the ranked-tiling method as outlined in Ghosh et
al. (2016). Observations were obtained in the q band using a 2x10-tile
strategy. Starting with the highest probability tiles a set of
10-tiles was observed in q-band filter (440-720nm) using 60s
exposures, which was repeated directly after the first 10 tiles were
observed. Subsequently tiles 11-20 were observed in the same two-visit
manner, etc.

Observations started at 2024-04-22 21:34 with MeerLICHT and 2024-04-22
23:10 with BlackGEM. Sutherland skies show high cirrus, which will
limit the photometric depth. La Silla skies are clear. Photometric depth
will be limited by the Full Moon.

All observations are reported to the Gravitational Wave Treasure Map
( Any candidates will be reported to the
GCN server as well as to the Transient Name Server

Observations are continuing. 

The BlackGEM/MeerLICHT telescopes are designed, installed and operated
by a consortium of the following universities and institutions:
Radboud University, Netherlands Research School for Astronomy NOVA, KU
Leuven, Armagh Observatory and Planetarium, Danish Technical
University, Durham University, Hebrew University of Jerusalem, South
African Astronomical Observatory, Tel Aviv University, Texas Tech
University, University of Amsterdam, University of Barcelona,
University of California at Davis, University of Cape Town, University
of Hamburg, University of Manchester, University of Oxford, University
of Potsdam, University of Valparaiso, University of Warwick, Weizmann

Ghosh et al., 2016, A&A 592, 82

Looking for U.S. government information and services? Visit