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 100625A: Enhanced Swift-XRT position
- GRB100625A : MOA optical upper limit
- GRB 100625A: Swift detection of a short hard burst
- GRB 100418A: late time optical observations
- Konus-Wind observation of GRB 100621A
- GRB 100621A: IRSF/SIRIUS NIR Observation
- GRB 100621A MOA-II optical limit
- GRB 100619A: Correction to the Fermi GBM trigger time
- GRB 100621A: Swift/UVOT observations
- GRB 100621A: Swift XRT refined analysis
- GRB 100621A: VLT/X-shooter redshift
- GRB 100621A: Swift-BAT refined analysis
- GRB 100621A: GROND observation of bright NIR afterglow
- GRB 100621A: Enhanced Swift-XRT position
- GRB 100621A: Prompt enhanced Swift-XRT position
- GRB 100621A: ROTSE-III Optical Limits
- GRB 100621A: Swift detection of a burst
- GRB 100606A: Optical Limits
- GRB 100619A: Fermi GBM detection
- GRB 100619A: Swift/UVOT Upper Limits
- GRB 100619A: Swift-XRT refind analysis
- GRB 100619A: Enhanced Swift-XRT position
- GRB 100619A: Swift-BAT refined analysis
- GRB 100619A: Swift detection of a burst
- GRB 100614A: Gemini/NIRI Observations
- GRB 100615A: Gemini/NIRI Observations
- XRF 100616a : MAXI/GSC detection of a probable XRF
- Fermi GBM trigger 100612038 is not a GRB
- GRB 100615A: Swift/UVOT Upper Limits
- GRB 100614A: Swift/UVOT Upper Limits
- GRB 100614A: NOT optical upper limits
- GRB 100614A: MASTER-Net optical alert observations
- GRB 100614A: Swift-BAT refined analysis
- GRB 100615A: Fermi GBM detection
- GRB 100615A: Swift-BAT refined analysis
- GRB 100614A: Enhanced Swift-XRT position
- GRB 100615A: Enhanced Swift-XRT position
- GRB 100615A: Swift-XRT refined analysis
- GRB 100614A: Swift-XRT refined analysis
- GRB 100614 : XMM-Newton observation
- GRB 100615A: GROND observations, upper limits
- GRB 100615A: PAIRITEL NIR Upper Limits
- GRB 100615A: NTT/Ultracam imaging
- GRB 100615A: Swift detection of a burst
- GRB 100614A: WHT I-band observations
- GRB 100614A: BOOTES-2/TELMA optical observations
- GRB 100614A: Liverpool Telescope Observations
- GRB 100614A: Swift detection of a burst
- GRB 100606A: Suzaku WAM observation of the prompt emission
- GRB 100606A: GROND observations
- Trigger 424161: Swift/BAT trigger on XTE J1946+274/GRO J1944+26
- Konus-Wind observation of GRB 100606A
- Radio detection of GRB100418a with ATCA
- GRB 100606A: Gemini-South imaging
- GRB 100606A: Swift/UVOT Upper Limits
- GRB 100606A Swift-XRT refined analysis
- GRB 100606A: Swift-BAT refined analysis
- GRB 100606A: Enhanced Swift-XRT position
- Swift Trigger 424040 is not a GRB
- GRB 100606A: Prompt enhanced Swift-XRT position
- GRB 100606A: Swift detection of a burst
- Swift detection of outburst from the SFXT IGR J18410-0535
- GRB 100111A: Maidanak optical observations
- GRB 100418A: Maidanak optical observations
- GRB 100513A: CrAO optical observations
- GRB 100514A: CrAO optical observations
- GRB 100526A: optical upper limit
- Konus-Wind observation of GRB 100528A
- GRB 100528A: Faulkes Telescope North Detection
- GRB 100528A: GROND detection in all bands
- GRB 100528A: NOT optical observation
- Swift UVOT and UVOT-enhanced XRT position for GRB 100528A
- GRB100526B: GROND Upper limits
- GRB 100528A: Fermi GBM observation
- GRB 100528A: SuperAGILE Localization of a Long GRB
- GRB 100526B: Swift-XRT confirmation of fading afterglow
- GRB 100526B: Swift/UVOT Upper Limits
- GRB 100526A: Swift/UVOT Upper Limits
- GRB 100526A: Gemini/NIRI infrared afterglow candidate
- GRB 100526A: NOT optical upper limit
- GRB 100526A: Swift XRT refined analysis
- GRB 100526B: Swift-BAT refined analysis
- GRB 100526B: Swift XRT/UVOT observations
- GRB 100526A: Swift-BAT refined analysis
- GRB 100526A: Enhanced Swift-XRT position
- GRB 100526B: Swift detection of a probable GRB
- GRB 100526A: MASTER-Net optical alert observations
- GRB 100526A: Swift detection of a burst
- Konus-Wind observation of GRB 100522A
- GRB100522A: Suzaku WAM observation of the prompt emission
- GRB 100418A: Subaru late-time optical imaging and spectroscopy
- GRB 100522A: GROND observations, upper limits
- Swift/UVOT observations of GRB100522A.
- GRB 100522A: Fermi GBM observation
- GRB 100522A: Swift XRT refined analysis
- GRB 100522A, Swift-BAT refined analysis
- GRB 100522A: Enhanced Swift-XRT position
- GRB 100522A: NIR observations from CAHA
- GRB 100522A: BOOTES-2 optical limit
- GRB 100522A: Swift detection of a burst