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 100111A: PAIRITEL NIR Upper Limits
- GRB 100111A: Swift UVOT Refined Analysis
- GRB 100111A: Swift-BAT refined analysis
- GRB 100111A: Enhanced Swift-XRT position
- GRB100111A: Swift-XRT refined analysis
- GRB 100111A: Fermi GBM observation
- GRB 100111A: NOT optical observations
- GRB 100111A: Swift detection of a burst with an optical afterglow
- Swift/BAT Detects an Outburst from XTE J1901+014
- Swift Trigger #382159 is due to XTE J1752-223
- GRB 100103A: GROND Upper Limits
- GRB 100103A: Swift-XRT team refined analysis
- GRB 100103A - UVOT-enhanced XRT position
- Konus-Wind observation of GRB 100103A
- GRB 100103A: Swift/UVOT Upper Limits
- GRB 100103A: Correction to Swift position error
- GRB 100103A: Swift/XRT position
- GRB 100103A: a long GRB detected with INTEGRAL
- Swift Trigger 381591: Retraction of Reported UVOT Source
- Swift Trigger 381591 is probably not a burst
- GRB 091231: GROND NIR observations
- Swift Trigger 381591: Uncatalogued UVOT Source
- GRB 091230: Swift/UVOT Observations
- Trigger 381591: Swift detection of a possible burst
- GRB 091230: Swift-XRT observation
- GRB 091230: GROND optical/NIR afterglow candidate
- GRB 091230: a long GRB detected by INTEGRAL
- Swift Trigger 381434 is not a GRB
- Trigger 381434: Swift detection of a possible burst
- GRB 091221 : IRSF NIR upper limit
- GRB 091221: Skynet/PROMPT Detections
- GRB 091221: Fermi GBM Observation
- GRB 091117: Swift-XRT late time observations
- GRB 091221 Swift-BAT refined analysis
- GRB091221: Swift/UVOT refined analysis, correction.
- GRB 091221: Swift/UVOT refined analysis
- GRB 091221: Swift-XRT refined analysis
- GRB 091221: Enhanced Swift-XRT position
- GRB 091221, GROND observations
- GRB 091221: UVOT Confirmation of an Optical Afterglow
- GRB 091221: ROTSE-III Detection of Optical Counterpart
- GRB 091221: Swift detection of a burst
- Swift trigger 379449 (possible GRB) is not a burst
- GRB 091215: Faulkes Telescope North observations
- Trigger 379449: Swift detection of a possible burst
- GRB 091208B: Xinglong TNT optical observation
- GRB 091208A: Suzaku WAM observation of the prompt emission
- GRB 091208A: GAO 150cm telescope Optical Observation
- Konus-Wind observation of GRB 091208A
- GRB 091208B: GAO 150cm telescope Optical Observation
- GRB091208A: Swift/UVOT refined analysis
- GRB 091208B: optical observations
- GRB 091208B: Keck HIRES redshift confirmation
- GRB 091208B: GROND observations
- GRB 091208A: Swift-XRT observations
- GRB091208B: NOT optical observations
- GRB 091208B: Swift-XRT refined analysis
- GRB091208B: Swift/UVOT refined analysis
- GRB 091208B: Fermi GBM observation
- GRB 091208B, Swift-BAT refined analysis
- GRB 091208A Swift-BAT refined analysis
- GRB 091208B: Gemini-North redshift
- GRB 091208B: Faulkes Telescope North and South Optical Afterglow
- GRB 091208A, RIMOTS optical upper limits
- GRB 091208B: MITSuME Akeno Optical Observation
- GRB 091208B: Enhanced Swift-XRT position
- GRB 091208B: MITSuME Okayama Optical Observation
- GRB 091208B, RIMOTS optical upper limits
- GRB 091208B: Swift detection of a burst with an optical afterglow
- GRB 091208B: BOOTES-3 optical afterglow
- GRB 091208: ROTSE-III Optical Limits
- GRB 091208: Swift detection of a burst
- Short X-ray Transient, RIMOTS optical upper limits
- A small revision to the GRB-naming convention
- GRB 091123: Suzaku WAM observation of the prompt emission
- GRB 091127: Skynet/PROMPT Observations of Possible Host Galaxy
- GRB 091127: GAO 150cm telescope Optical Observation
- GRB 091202: GTC & CAHA optical/nIR afterglow candidate
- GRB 091109A: GROND confirmation of redshift z = 3.5
- GRB091127: Continuing Swift/UVOT Observations
- GRB 091127, SMARTS optical/IR afterglow observations
- GRB091202: Swift-XRT refined analysis
- GRB 091202: Swift/UVOT Upper Limits
- GRB 091202: Liverpool Telescope observations
- GRB 091202: Optical and NIR observations
- GRB 091202 - UVOT-enhanced XRT position
- GRB 091127: Zadko Telescope Observations
- GRB 091126A: Suzaku WAM observation of the prompt emission
- GRB 091202: TAROT Calern observatory optical observations
- GRB 091202: Liverpool Telescope Observations
- GRB 091202: a long GRB detected by INTEGRAL
- GRB 091127: redshift confirmation with X-shooter
- GRB 091117: Chandra Observations
- GRB 091020: MASTER-Net optical polarization observations
- GRB 091127: Skynet/PROMPT Continued Observations of Fading
- Short X-ray Transient Detection by MAXI/GSC
- Konus-Wind observation of very long GRB 091123
- GRB 091130A: Xinglong TNT upper limit
- GRB 091123: Fermi GBM detection of a very long burst
- GRB 091126B: Fermi GBM detection