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').
- Swift GRB 210820A: Global MASTER-Net observations report
- GRB 210820B: Fermi GBM Final Localization
- GRB 210820A: Swift detection of a burst with an optical counterpart
- Fermi trigger No 651110719: Global MASTER-Net observations report
- Swift GRB210818.68: Global MASTER-Net observations report
- Swift GRB 210818A: Global MASTER-Net observations report
- GRB 210818A: Swift-XRT refined Analysis
- GRB 210818A: Swift-BAT refined analysis
- GRB 210726A: VLA radio afterglow detection
- Konus-Wind detection of GRB 210818A
- Swift Trigger 1069242 is Cyg X-1
- GRB 210818A: AstroSat CZTI detection
- GRB 210818A: AGILE detection
- GRB 210818A: Enhanced Swift-XRT position
- GRB 210818A: Swift detection of a burst with an optical counterpart
- IceCube-210811A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-210730A: not observable by Fermi-GBM
- IceCube-210811A: Upper limits from Fermi-GBM Observations
- GRB 210815A: BALROG localization (Fermi Trigger 650687034 / GRB 210815100)
- GRB 210815A: Fermi GBM Final Real-time Localization
- Fermi trigger No 650687034: Global MASTER-Net observations report
- GRB 210812A is consistent with being a lensed GRB
- IceCube-210811A: No Candidate Counterparts from the Zwicky Transient Facility
- GRB 210712A: Fermi GBM observation
- GRB 210813A: BALROG localization (Fermi Trigger 650508868 / GRB 210813038)
- Fermi GRB 210813A: Global MASTER-Net observations report
- GRB 210813A: Fermi GBM Final Real-time Localization
- Fermi-LAT Gamma-ray Observations of IceCube-210811A
- Retraction of Fermi GBM GCN 30630 and GCN 30632
- GRB 210807A: continued Assy, AbAO and Mondy observations
- Fermi GRB 210812A: Global MASTER-Net observations report
- GRB 210812B: Fermi GBM Final Real-time Localization
- GRB 210812A: BALROG localization (Fermi Trigger 650479626 / GRB 210812699)
- GRB 210812A: Fermi GBM Final Real-time Localization
- GRB 080102A: Fermi GBM Final Real-time Localization
- SGR 1935+2154: SPI INTEGRAL observations on 2021 August 5
- GRB 080101A: Fermi GBM Final Real-time Localization
- GRB 210730A: Tautenburg observations
- GRB 210807A: Tautenburg observations
- IceCube-210811A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 210811.09: Global MASTER-Net observations report
- GRB 210807C: Swift-BAT refined analysis
- GRB 210807A: Detection by GRBAlpha
- GRB 210807A: Swift-BAT refined analysis
- GRB 210802A: Further Swift/XRT observation and afterglow confirmation
- GRB 210807C: Swift-XRT refined Analysis
- GRB 210807C: Fermi GBM detection
- GRB 210807C: Swift/UVOT Upper Limits
- GRB 210807A: Swift/UVOT Detection
- GRB 210807A: Swift-XRT refined Analysis
- GRB 210807A: correction to the GCN Circ. #30614 Assy optical observations
- GRB 210807C: Enhanced Swift-XRT position
- GRB 210610B: Assy optical observations
- Swift GRB210807.74: Global MASTER-Net observations report
- Fermi GRB 210807C: Global MASTER-Net observations report
- Swift GRB210807.96: Global MASTER-Net observations report
- GRB 210807C: Swift detection of a burst
- GRB 210807C: Fermi GBM Final Real-time Localization
- Fermi GRB 210807B: Global MASTER-Net observations report
- Swift GRB 210807A: Global MASTER-Net observations report
- Swift GRB210807.79: Global MASTER-Net observations report
- Swift GRB210807.78: Global MASTER-Net observations report
- Fermi trigger No 650046564: Global MASTER-Net observations report
- GRB 210807A: Enhanced Swift-XRT position
- GRB 210807A: BOOTES-5/JGT optical afterglow detection
- GRB 210807B: Fermi GBM Final Real-time Localization
- GRB 210807A: Swift detection of a burst with an optical counterpart
- Konus-Wind detection of a burst from SGR 1935+2154 on 2021 August 5
- IPN Triangulation of a bright burst from SGR 1935+2154
- Fermi trigger No 649814537: Global MASTER-Net observations report
- GRB 210802A: MITSuME Okayama optical upper limits
- GRB 210803A: Fermi GBM observation
- Fermi trigger No 649684549: Global MASTER-Net observations report
- GRB 210802A: DDOTI Upper Limits
- GRB 210802A: BOOTES-2/TELMA optical upper limit
- GRB 210802A: Swift-XRT afterglow detection
- GRB 210802A: Fermi GBM detection
- GRB 210802A: Fermi-LAT detection
- GRB 210803A: BALROG localization (Fermi Trigger 649684549 / GRB 210803497)
- GRB 210802A: Tiled Swift observations
- Fermi trigger No 649627691: Global MASTER-Net observations report
- GRB 210801A: Fermi GBM detection
- GRB 210731A: continued GROND observations
- GRB 210731A: VLT/X-shooter redshift
- GRB 210731A: KAIT Optical Detection
- IceCube-210730A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 210731A: Swift-BAT refined analysis
- Fermi trigger No 649524889: Global MASTER-Net observations report
- GRB 210731A: MASTER optical afterglow detection
- GRB 210801A: BALROG localization (Fermi Trigger 649519043 / GRB 210801581)
- GRB 210731A: Swift-XRT refined Analysis
- Fermi trigger No 649519043: Global MASTER-Net observations report
- GRB 210731A: GROND observations
- GRB 210731A: Fermi GBM Observation
- GRB 210731A: Swift/UVOT Detection of an optical afterglow
- Swift GRB210731.62: Global MASTER-Net observations report
- GRB 210731A: MeerLICHT optical afterglow detection
- GRB210731A: Enhanced Swift-XRT position
- GRB 210731A: Swift detection of a burst
- Swift GRB210731.93: Global MASTER-Net observations report