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 090102: GROND observations of the optical afterglow
- Swift UVOT observations of GRB 090102
- GRB 090102: Swift-BAT refined analysis
- GRB 090102: Swift burst of interest
- GRB 090102: Swift XRT refined analysis
- GRB 090102: NOT redshift
- GRB 090102: Enhanced Swift-XRT position
- GRB 090102: TAROT Calern observatory optical light curve
- GRB 090102: REM observations of a bright afterglow
- GRB 090102: Swift detection of a burst with an optical counterpart
- GRB 090102: TAROT Calern observatory optical observations
- GRB 081230: GROND confirmation of the afterglow
- GRB 081230, Swift-BAT refined analysis
- GRB081230: Swift-XRT refined analysis
- GRB 081230 Swift/UVOT Observations
- GRB 081230: Enhanced Swift-XRT position
- GRB 081230: Swift/UVOT Detection of an Optical Afterglow
- GRB 081230: ROTSE-III Detection of Optical Counterpart
- GRB 081230: Swift detection of a burst
- GRB 081228: GROND confirmation of the optical/NIR afterglow
- GRB 081226B: Fermi GBM observation
- GRB 081226C: Fermi GBM detection
- GRB 081228, Swift-BAT refined analysis
- VLA radio detection of GRB 081221
- GRB 081228: Swift/UVOT Upper Limits
- GRB 081228: Swift-XRT Team refined analysis
- GRB 081228: detection by GROND
- GRB 081228: Enhanced Swift-XRT position
- GRB 081228: TAROT Calern observatory optical observations
- GRB 081228: Swift detection of a burst
- VLA radio observation of GRB 081221
- GRB 081226B: Swift XRT and UVOT upper limits
- GRB 081224: Suzaku WAM observation of the prompt emission
- GRB 081226: Swift-XRT refined analysis
- GRB 081226A: Swift UVOT Upper Limits
- GRB 081226: Second epoch of Gemini-South imaging
- GRB 081226A: Swift-BAT refined analysis
- GRB 081226B: a short-hard GRB detected by INTEGRAL
- GRB 081226: Gemini-South spectrum of possible afterglow
- GRB 081226: Gemini-South imaging
- GRB 081226: GROND afterglow candidate
- GRB 081226: ROTSE-III Optical Limits
- GRB 081226: Swift detection of a possible short-hard burst
- GRB 080810: optical observations
- GRB 081211B: optical observations
- GRB081224: LAT retraction
- GRB 081224: Swift-XRT observation
- GRB 081222: MITSuME optical observation
- GRB 081224: Fermi GBM Detection & LAT Localization
- GRB 080810: optical observations
- Konus-Wind observation of GRB 081222
- GRB 081223: Fermi GBM detection
- GRB 081221: GROND observations
- GRB 081222: Gemini-N confirmation of redshift z=2.77
- GRB 081222:Optical afterglow observation
- VLA radio upper limit on GRB 081222
- GRB 081222: Fermi GBM observation
- Fermi Gamma-ray Burst Monitor trigger 251687595 reclassification
- GRB 081222: Gemini-South absorption redshift
- GRB081222: Swift/UVOT further observations
- GRB 081221: Probable host galaxy in Keck imaging
- GRB 081204C: Fermi GBM detection
- GRB 081222, Swift-BAT refined analysis
- GRB 081221, Swift-BAT refined analysis
- GRB081222 optical limit by "Pi of the Sky"
- Konus-Wind observation of very bright GRB 081215A
- GRB 081222: Swift XRT refined analysis
- GRB081221: Fermi GBM observation
- Swift/UVOT observations of GRB 081221
- IPN triangulation of bright GRB 081215A
- GRB 081221: Swift-XRT Refined Analysis
- GRB 081221: pseudo-redshift (pz=0.7) from the spectral parameters of the prompt emission
- GRB 081222: Faulkes Telescope South observations
- GRB 081221: Gemini-N nIR imaging
- GRB081222, optical observation
- GRB081222: Swift/UVOT detection of an optical afterglow
- GRB081203A: BTA observation
- Konus-Wind observation of GRB 081221
- GRB 081222: GROND Detection of the Optical/NIR Afterglow
- GRB081222: REM candidate afterglow
- GRB 081222: Swift detection of a burst with a bright optical afterglow
- GRB 081221: Enhanced Swift-XRT position
- GRB 081221: further NOT observations
- GRB 081221: NOT observations
- GRB 081221: Swift detection of a burst
- GRB 081217: Fermi GBM detection
- Modification of Swift/UVOT response to bright GRBs
- GRB081215A: Fermi-LAT observations
- GRB 081211B: Further Swift-XRT analysis
- GRB 081215B: Fermi GBM detection
- GRB 081216: Suzaku WAM observation of the prompt emission
- GRB 081216 : Fermi GBM observation
- GRB 081215A: Fermi GBM detection (correction to event fluence)
- GRB 081215A: Fermi GBM detection
- IPN localization of short hard GRB 081216
- GRB 081211B - possibly a short burst with extended emission
- GRB 081118: Zadko observations
- Fermi Trig Num 251059717 = SGR 0044+42: MASTER prompt optical observations
- GRB 081215A: Gamma Repeater?
- GRB 0811215A: MASTER prompt optical observations