GCN Circulars
GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
- GRB 210702A: BOOTES-3/YA optical counterpart observations
- Konus-Wind detection of GRB 210702A
- GRB 210702A: Chilescope optical observations
- GRB 210702A: iTelescope optical afterglow observations
- GRB 210702A: AGILE detection
- GRB 210702A: CALET Gamma-Ray Burst Monitor detection
- GRB 210619B: JCMT SCUBA-2 sub-mm observations
- GRB 210610B: JCMT SCUBA-2 sub-mm observations
- GRB 210610A: JCMT SCUBA-2 sub-mm observations
- GRB 210702A: Swift-XRT refined Analysis
- GRB 210702A: VLT/X-shooter redshift
- GRB 210702A: preliminary Swift/UVOT photometry
- GRB 210702A: Swift/UVOT redshift
- GRB210702A: MeerLICHT multi-colour photometry
- Swift GRB 210702A: Global MASTER-Net observations report
- Swift GRB210702.80: Global MASTER-Net OT detection
- GRB 210702A: Swift detection of a burst with a bright optical counterpart
- IceCube-210629A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-210629A: One Candidate Counterpart from the Zwicky Transient Facility
- IceCube-210629A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- Fermi-LAT Gamma-ray Observations of IceCube-210629A
- IceCube-210629A: Upper limits from Fermi-GBM Observations
- GRB 210627B: GECAM detection
- IceCube Alert 210629.76: Global MASTER-Net observations report
- GRB 210619B: Sayan observatory 1.6-m telescope observations
- IceCube-210629A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 210626A: Swift/XRT afterglow confirmation
- GRB 210626A: Fermi GBM observation
- GRB 210626A: CAHA 2.2m telescope optical limit
- GRB 210619B: Deep CAHA 2.2m detection and late-time light curve behavior
- GRB 210626A: Ondrejov D50 optical limit
- GRB 210626A: GIT optical upper limit
- Fermi trigger No 646443989: Global MASTER-Net observations report
- Fermi GRB 210627B: Global MASTER-Net observations report
- GRB 210627B: BALROG localization (Fermi Trigger 646509445/ GRB 210627748)
- GRB 210627B: Fermi GBM Final Real-time Localization
- Fermi GRB 210627A: Global MASTER-Net observations report
- GRB 210627A: Fermi GBM Final Real-time Localization
- GRB 210626A: Swift-XRT afterglow detection
- Fermi trigger No 646322348: Global MASTER-Net observations report
- Fermi GRB 210626A: Global MASTER-Net observations report
- GRB 210626A: Swift ToO observations
- GRB 210626A: Swift/BAT-GUANO detection and arcminute localization
- GRB 150428A: late-time radio observations
- GRB 210626A: Fermi GBM Final Real-time Localization
- GRB 210618A: 1.5m OSN optical upper limit
- Fermi GRB 210625A: Global MASTER-Net observations report
- GRB210619B: optical afterglow detection from Konkoly Observatory
- GRB 210625A: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 210624A (short)
- GRB 210622A: Swift-XRT observations
- GRB 210610B: T-CAT optical observations
- GRB 210619B: ASIM observation
- Fermi trigger No 646189108: Global MASTER-Net observations report
- Fermi GBM observation of a bright burst in the direction of SGR 1935+2154
- GRB 210618A: Swift-XRT afterglow detection
- Fermi trigger No 646194855: Global MASTER-Net observations report
- GRB 210622A: Swift ToO observations
- GRB 210619B: Even further SAO RAS optical observations
- GRB 210619B: Mini-MegaTORTORA early optical observations
- Fermi GRB 210622B: Global MASTER-Net observations report
- GRB 210622A: Fermi GBM detection
- GRB 210619B: Abbey Ridge Observatory optical afterglow observation
- GRB 210619B: SPI-ACS/INTEGRAL observations
- GRB 210619B: Further SAO RAS optical observations
- GRB 210622A: Swift/BAT-GUANO detection and arcminute localization of a long burst
- GRB 210619B: possibility of lensed visible afterglow?
- GECAM detection of GRB 210622B
- GRB 210619B: AbAO optical observations
- GRB 210622B: Fermi GBM Final Real-time Localization
- GRB 210622A: Fermi GBM Final Real-time Localization
- Swift Trigger 1057131: detection of a burst from SGR Swift J1555.2-5402
- Swift GRB210621.71: Global MASTER-Net observations report
- GRB 210619B: NOT optical observations
- GRB 210619B: 1.5m OSN optical observation
- GRB 210619B: iTelescope optical afterglow observation
- GRB 210619B: SAO RAS optical observations
- GRB 210619B: SEDM Optical Observations
- GRB 210619B: TNG NIR observations of the afterglow
- GRB 210619B: REM optical/NIR afterglow detection
- Fermi GRB 210621A: Global MASTER-Net observations report
- GRB 210619B: GIT optical follow-up and confirmation of jet-break
- GRB 210621A: Fermi GBM Final Real-time Localization
- GRB 210619B: CALET Gamma-Ray Burst Monitor detection
- GRB 210619B: SRG/ART-XC detection
- GRB 210619B: Swift-BAT refined analysis
- GRB 210619B: steepening of the decay observed at the D50
- GRB 210619B: Liverpool Telescope First Hour Observations
- GRB 210619B: Fermi GBM detection
- GRB 210619B: Swift/UVOT Detection
- GRB 210619B: Xinglong TNT optical observations
- Konus-Wind detection of GRB 210619B
- GRB 210619B: CAHA 2.2m photometric monitoring
- GRB 210619B: Liverpool Telescope r'-band observations
- GRB 210619B: KAIT Optical Detection
- GRB 210619B: Redshift from OSIRIS/GTC
- GRB 210619B: Liverpool telescope imaging of a red afterglow
- GRB 210619B: Fermi-LAT detection
- GRB 210619B: Swift-XRT refined Analysis
- GRB 210619B: SARA-KP 0.9m Optical Afterglow Detection