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"- Konus-Wind observation of GRB 180620A
- GRB 180620B: VLT/X-shooter redshift
- Konus-Wind observation of GRB 180618A (a short GRB with extended emission)
- GRB 180620B: Swift-BAT refined analysis
- GRB 180613A: Afterglow confirmation and added photometry
- GROND observations of GRB 180620B
- GROND observations of GRB 180620A
- GRB 180620B: Swift-XRT refined Analysis
- GRB 180618B: CALET Gamma-Ray Burst Monitor detection
- GRB 180620A: Swift-BAT refined analysis
- GRB 180620B: Enhanced Swift-XRT position
- GRB 180620B: Fermi GBM detection
- GRB 180620A: KAIT Optical Observations
- GRB 180620A: Xinglong-2.16m optical observations
- GRB 180618A: Swift/UVOT Detection
- GRB 180618A: TSHAO optical upper limit
- GRB 180620A: Swift-XRT refined Analysis
- GRB 180620B: Swift detection of a burst with an optical counterpart
- GRB 180620A: COATLI Detection and Light Curve
- GRB 180620A: Swift/UVOT Detection
- GRB 180618A: Xinglong-2.16m optical upper limit
- GRB 180620A: LCO McDonald observations
- GRB 180620A: Enhanced Swift-XRT position
- GRB 180620A: MASTER OT observation
- GRB 180620A: ISON-MN afterglow confirmation
- GRB 180620A: RATIR Optical Afterglow Detection
- GRB 180620A: Swift detection of a burst with an optical counterpart
- GRB 180618A: MASTER OT observation (a short GRB with extended emission)
- GRB 180618A: Swift-BAT refined analysis (a short GRB with extended emission)
- GRB 180611A: AstroSat CZTI detection
- GRB 180618A: Fermi GBM detection
- GRB 180618A: Swift-XRT refined Analysis
- GRB 180618A: LT prompt observations
- GRB 180618A: Enhanced Swift-XRT position
- GRB 180618A: Swift detection of a burst with an optical counterpart
- GRB 180614A: AbAO optical observations
- GRB 180614A: 1.5m OSN I-band observation
- GRB 180614A: Swift/UVOT Upper Limits
- GRB 180614A: Swift-BAT refined analysis
- GRB 180529A: AstroSat CZTI detection
- GRB 180614A: NOT optical upper limits
- GRB 180614A: MASTER observation
- GRB 180614A: Swift-XRT refined Analysis
- GRB 180614A: Enhanced Swift-XRT position
- GRB 180614A: Swift detection of a burst
- GRB 180613A: Swift/UVOT Upper Limits
- GRB 180613A GROND observations: correction
- GRB 180613A GROND observations
- GRB 180613A, Swift-BAT refined analysis
- GRB 180613A: Possible IR afterglow
- GRB 180613A: Swift-XRT refined Analysis
- GRB 180613A: Enhanced Swift-XRT position
- GRB 180613A: Possible host galaxy at XRT position, or star
- GRB 180613A: Prompt enhanced Swift-XRT position
- Konus-Wind observation of GRB 180611A
- GRB 180613A: Swift detection of a burst
- GRB 180611A: Fermi GBM observation
- IPN Triangulation of GRB 180611A (long)
- GRB 180605A: Fermi GBM observation
- GRB 180605A: AstroSat CZTI detection
- IPN Triangulation of GRB 180605A (long)
- GW170817/GRB170817A: LBT optical detection
- GRB 180603A: AstroSat CZTI detection
- Fermi GBM trigger 180604900/549840956 likely not a GRB
- GRB 180602A: MITSuME Ishigakijima optical upper limits
- GRB 180602B: Fermi GBM detection
- GRB 180602A: Swift/UVOT Upper Limits
- GRB 180602A: MITSuME Akeno optical upper limits
- GRB 180602A: Swift-XRT refined Analysis
- GRB 180602A: Swift-BAT refined analysis
- GRB 180602A: MITSuME Okayama optical upper limits
- GRB 180602A: Enhanced Swift-XRT position
- GRB 180602A: Swift detection of a burst
- Fermi GBM trigger 549533811/180601345 is not a GRB
- Konus-Wind observation of GRB 180529A
- GRB 180529A: CALET Gamma-Ray Burst Monitor detection
- IPN Triangulation of GRB 180529A (short/hard)
- Swift Trigger 834937 is not a GRB
- Konus-Wind observation of GRB 180526A
- IPN Triangulation of GRB 180526A (long)
- GRB 180526A: CALET Gamma-Ray Burst Monitor detection
- Konus-Wind observation of GRB 180523A
- GRB 180526A: AstroSat CZTI detection
- AGILE/MCAL detection of GRB 180529 and a possible precursor
- IPN Triangulation of GRB 180523A
- GRB180523B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 548793993)
- GRB 180523A: CALET Gamma-Ray Burst Monitor detection
- Fermi GBM trigger 548829437/180524192 is not a GRB
- GRB 180514A: MITSuME Ishigakijima optical upper limits
- GRB 180514A: CrAO/ZTSH optical observations and afterglow candidate
- GRB 180505A: AstroSat CZTI detection
- GRB 180514A: Swift/UVOT Upper Limits
- GRB 180514A: MITSuME Akeno optical upper limits
- GRB 180514A: Detection limits from 2.5m NOT
- GRB 180510A: MITSuME Ishigakijima optical upper limits
- GRB 180514A: 1.5m OSN optical observations
- GRB 180514A: GOTO Optical Observations
- GRB 180514A: Swift-BAT refined analysis
- GRB 180514A: Swift-XRT refined Analysis
- GRB 180514A: Enhanced Swift-XRT position