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.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
- Fermi trigger No 648033323: Global MASTER-Net observations report
- Fermi trigger No 648024201: Global MASTER-Net observations report
- Fermi trigger No 647942198: Global MASTER-Net observations report
- GRB 210712A: Swift-BAT refined analysis
- GECAM detection of a short burst from SGR J1935+2154
- Recent activity of SGR 1935+2154 as observed by CGBM
- GRB 210712A: Swift-XRT refined Analysis
- GRB 210712A: Swift/UVOT Upper Limits
- GRB 210712A: BOOTES-3/YA optical upper limit
- Fermi trigger No 647805873: Global MASTER-Net observations report
- GRB 210712A: Enhanced Swift-XRT position
- GRB 210704A: classification as long GRB and redshift estimating
- GRB 210704A: Lowell Discovery Telescope Optical Observations
- Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 10
- GECAM detection of a short burst from SGR J1935+2154
- Fermi trigger No 647775795: Global MASTER-Net observations report
- GRB 210712A: Swift detection of a burst
- GRB 210709A: AstroSat CZTI detection
- GRB 210704A: Continued Gemini-North NIR K-band Detections
- GRB 210704A: INTEGRAL observations
- GRB 210704A: NOT optical observations and color change
- GRB210704A: Gemini near-infrared upper limits
- Fermi trigger No 647653174: Global MASTER-Net observations report
- GRB 210704A: Assy optical afterglow upper limit
- Fermi trigger No 647641569: Global MASTER-Net observations report
- Fermi trigger No 647624281: Global MASTER-Net observations report
- GECAM detection of a short burst from SGR J1935+2154
- GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy
- MAXI GRB210709.93: Global MASTER-Net observations report
- Fermi trigger No 647522278: Global MASTER-Net observations report
- GRB 210704A: Gemini-North Infrared Source Detection
- GRB 210704A: further TNG optical observations
- GRB 210706A: Swift/XRT afterglow confirmation
- GECAM detection of a short burst from SGR 1935+2154
- GRB 210708B: Swift-BAT refined analysis
- Fermi GRB 210709A: Global MASTER-Net observations report
- GRB 210709A: Fermi GBM Final Real-time Localization
- Swift GRB 210708B: Global MASTER-Net observations report
- GRB 210708A: Swift/UVOT Upper Limits
- GRB 210702A: ATCA detection
- GRB 210702A: ALMA detection
- GRB 210708A: Swift-BAT refined analysis
- Fermi GBM Sub-Threshold Detection of GRB 210708A
- Fermi GBM Sub-Threshold Detection of GRB 210707A
- IceCube-210629A - Spectroscopic observation of AT2021osi
- Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 7
- GRB 210708B: Swift detection of a possible burst
- GRB 210708A: Swift-XRT refined Analysis
- GECAM detection of a short burst from SGR 1935+2154
- GRB 210707A: A long GRB detected by INTEGRAL
- GRB 210708A: Swift detection of a burst
- Swift GRB210708.10: Global MASTER-Net observations report
- GRB 210704A: CAHA 2.2m telescope optical limit
- Fermi trigger No 647365516: Global MASTER-Net observations report
- Konus-Wind detection of a burst from SGR 1935+2154 on 2021 July 6
- Fermi trigger No 647271699: Global MASTER-Net observations report
- Fermi GBM Observations of SGR J1935+2154
- Swift-BAT detection of a burst from SGR 1935+2154
- GRB 210706A: Fermi GBM observation
- GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
- Konus-Wind detection of GRB 210706A
- GRB 210706A: GIT optical upper limits
- GRB 210704A: OAJ T80 multi-color detections
- GECAM detection of a bright short burst from SGR 1935+2154
- GRB 210706A: Swift-XRT afterglow detection
- Integral GRB210707.02: Global MASTER-Net observations report
- GRB 210706A: Swift ToO observations
- Fermi trigger No 647252274: Global MASTER-Net observations report
- INTEGRAL detection of a burst from SGR 1935+2154
- Integral GRB210706.72: Global MASTER-Net observations report
- GRB 210706A: Swift/BAT-GUANO detection and arcminute localization
- GRB 210704A: OSIRIS/GTC spectroscopy
- GRB 210704A: CAHA 2.2m Afterglow Detection
- GRB 210704A: RATIR optical upper limits
- GRB 210704A: Swift/UVOT Upper Limits
- Konus-Wind detection of GRB 210704A
- GRB 210704B: AstroSat CZTI detection
- GRB 210619B: ALMA detection
- GRB 210704A: TNG detection of the optical afterglow candidate
- GRB 210704A: Assy optical afterglow candidate
- GRB 210704A: DDOTI upper limit
- GRB 210704B: Fermi GBM detection
- GRB 210704A: possible local hosts
- GRB 210704A: Fermi GBM detection
- GRB 210704A: Swift-XRT afterglow detection
- GRB 210704A: AstroSat CZTI detection
- IceCube-210516A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- IceCube-210510A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 210704A: Fermi-LAT detection
- GRB 210704A: Swift ToO observations
- GRB 210705A: AGILE/MCAL detection of a burst
- GRB 210704A: AGILE/MCAL detection
- Fermi trigger No 647108723: Global MASTER-Net observations report
- Fermi trigger No 647120009: Global MASTER-Net observations report
- GRB 210704A: BALROG localization (Fermi Trigger 647120009 / GRB 210704815)
- GRB 210702A, Swift-BAT refined analysis
- 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