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').
Advanced Search
To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.
Advanced Search Examples (click to copy):
subject:"Swift"body:"GRB"submitter:"Judith Racusin"- GRB 180418A: 1.5m OSN optical observations
- GRB 180418A: Fermi GBM observation
- GRB 180418A: Swift-XRT refined Analysis
- GRB 180416B: CALET Gamma-Ray Burst Monitor detection
- GRB 180418A: RATIR Optical Observations
- LIGO/Virgo G299232: LOFAR follow-up
- GRB 180418A: Enhanced Swift-XRT position
- GRB 180418A: Swift-XRT observations
- GRB 180418A: LCO FTN afterglow confirmation
- GRB 180418A: KAIT Optical Afterglow Candidate
- GRB 180418A: Swift detection of a short burst
- GRB 180404B: AstroSat CZTI detection
- GRB 180416A: Fermi GBM detection
- GRB 180409A: Swift-XRT afterglow detection
- GRB 180411A: CALET Gamma-Ray Burst Monitor detection
- GRB 180411B: CALET Gamma-Ray Burst Monitor detection
- Konus-Wind observation of GRB 180411A
- GRB 180411A: Swift/UVOT Upper Limit
- GRB 180411A: Tautenburg observations
- GRB 180410A: Fermi GBM observation
- GRB 180409A CALET Gamma-Ray Burst Monitor detection
- GRB 180411A: Fermi GBM detection
- GRB 180411A: Swift-BAT refined analysis
- GRB 180411A: Swift-XRT refined Analysis
- GRB 180410A: RATIR Optical Observations
- GRB 180411A: Swift detection of a burst
- GRB 180410A: Swift-XRT refined Analysis
- GRB 180410A: Swift-BAT refined analysis
- GRB 180410A: Swift/UVOT Upper Limits
- GRB 180409A: Fermi GBM observation
- GRB 180409A: Swift-XRT observations
- Konus-Wind observation of GRB 180404C
- GRB 180410A: MITSuME Akeno optical upper limits
- GRB 180410A: Enhanced Swift-XRT position
- Konus-Wind observation of GRB 180409A
- GRB 180410A: Swift detection of a burst or a Galactic transient.
- IPN Triangulation of GRB 180409A
- GRB 180409A: Tiled Swift observations
- GRB 180402A: ISON-NM early optical limits
- GRB 180407A: Swift-BAT refined analysis
- Swift Trigger 823014: TAROT Calern observatory optical observations
- GRB 180407A: COATLI Upper Limits
- Swift Trigger 823014 is probably not a GRB
- GRB 180407A: Swift detection of a burst
- GRB 180404B: Swift/UVOT Detection
- IPN Triangulation of GRB 180404C (long)
- Konus-Wind observation of GRB 180404B
- Chandra observations of GRB161219B 400 days after the explosion
- GRB 180404C CALET Gamma-Ray Burst Monitor detection
- Fermi GBM triggers 544628550/180405571, 544542853/180404579, 544531428/180404447 are not GRBs
- GRB 180404A: Swift/UVOT Detection
- GRB 180404A: LCO FTS observations
- GRB 180404A: Swift-XRT refined Analysis
- GRB 180404B: Swift-BAT refined analysis
- GRB 180402A: Fermi GBM refined spectral analysis
- GRB 180404A: Swift-BAT refined analysis
- GRB 180404B: Swift-XRT refined Analysis
- GRB 180404B: Fermi GBM observation
- GRB 180404B: MASTER-OAFA OT observation
- Fermi GBM triggers 544440014/180403389 and 544451446/180403521 are not GRBs
- GRB 180404B: Enhanced Swift-XRT position
- GRB 180404A: MASTER-OAFA OT observation
- GRB 180404A: Enhanced Swift-XRT position
- GRB 180404A: VLT/X-shooter redshift
- GRB 180404B: Swift detection of a burst with an optical counterpart
- GRB 180404A: Swift detection of a burst with an optical afterglow
- Konus-Wind observation of GRB 180402A
- GRB 180402A: Swift/UVOT Upper Limits
- GRB 180402A: Swift-XRT refined Analysis
- GRB 180402A: Fermi GBM detection
- GRB 180402A, Swift-BAT refined analysis
- GRB 180402A: KAIT Optical Upper Limit
- GRB 180402A: RATIR Upper Limits
- GRB 180402A: LCO McDonald observations
- GRB 180402A: Swift detection of a possibly short burst
- GRB 180331B: Swift/UVOT Upper Limits
- GRB 180331B: Swift-XRT refined Analysis
- GRB 180331B: AbAO optical observations
- GRB 180331B: Swift-BAT refined analysis
- GRB 180331B: Enhanced Swift-XRT position
- GRB 180331A: Swift-BAT refined analysis
- GRB 180331B: Swift detection of a burst
- GRB 180331A: Swift-XRT refined Analysis
- GRB 180329B: LCO FTS observations
- GRB 180331A: Swift/UVOT Upper Limits
- GRB 180331A: Enhanced Swift-XRT position
- GRB 180331A: Swift detection of a burst
- GRB 180329B: VLT/X-shooter spectroscopic observations
- GRB 180329B: Swift-BAT refined analysis
- GRB 180329B: Swift/UVOT Detection
- GRB 180329B: RATIR Optical Observations
- Swift Trigger 819863 is not a GRB
- GRB 180329B: NOT optical afterglow detection
- GRB 180329A: Swift-BAT refined analysis
- GRB 180329B: Swift-XRT refined Analysis
- GRB 180329B: Enhanced Swift-XRT position
- GRB 180329B: Swift detection of a burst with an optical afterglow
- GRB180325A: AstroSat CZTI detection
- Swift Trigger 819301: possible GRB 180329A
- GRB 180325A: VLT/X-shooter spectroscopic observations