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 180630A: Swift detection of a burst with an optical counterpart
- GRB 180626C: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 551697835)
- GRB 180626A: TSHAO optical upper limit
- Konus-Wind observation of GRB 180626A
- Konus-Wind observation of GRB 180626C
- GRB 180624A: NOT optical counterpart
- Konus-Wind observation of GRB 180626B
- GRB 180626A: RATIR Optical Observations
- IPN Triangulation of GRB 180626C (short)
- IPN Triangulation of GRB 180626B (short)
- GRB 180626A: Swift-BAT refined analysis
- GRB 180626A: KAIT Optical Upper Limit
- GRB 180626A: Swift-XRT refined Analysis
- GRB 180626A: COATLI Optical Detection
- GRB 180624A: LCO Haleakala observations
- GRB 180626A: Swift/UVOT Detection
- Konus-Wind observation of GRB 180623A
- GRB 180626A: RATIR Optical Detection
- GRB 180626A: LCO Haleakala observations
- GRB 180626A: ISON-MN optical observations
- GRB 180626A: Enhanced Swift-XRT position
- GRB 180626A: A long GRB detected by INTEGRAL
- GRB 180626A: Swift detection of a burst with an optical counterpart
- GRB 180623B: CALET Gamma-Ray Burst Monitor detection
- GRB 180624A: Swift-BAT refined analysis
- AT2018cow: Swift/BAT data search
- GRB 180624A: RATIR Optical Observations
- GRB 180624A: LBT/MODS redshift measurement
- GRB 180620B: AstroSat CZTI detection
- GRB 180620A: AstroSat CZTI detection
- GRB 180618A: AstroSat CZTI detection
- GRB 180613A: LCO Afterglow detection
- GRB 180624A: GROND observations
- GRB 180624A: LCO Siding Springs afterglow candidate
- GRB 180624A: MITSuME Okayama optical upper limits
- GRB 180624A: Swift-XRT refined Analysis
- GRB 180624A: Swift/UVOT Upper Limits
- GRB 180624A: Enhanced Swift-XRT position
- GRB 180623A: retraction of the Swift/UVOT Detection
- GRB 180623A: Swift-BAT refined analysis
- GRB 180624A: Swift detection of a burst
- GRB 180623A: Swift/UVOT Detection
- GRB 180623A: Swift-XRT refined Analysis
- GRB 180623A: Enhanced Swift-XRT position
- GRB 180623A: Swift detection of a burst
- GRB 180620B: Swift/UVOT Detection
- GRB 180620A iTelescope observation
- Konus-Wind observation of GRB 180620B
- 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