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 121117A: Optical observations
- Konus-Wind observation of GRB 121118B
- GRB 121117A: optical upper limit
- IPN Triangulation of GRB 121118B (long/intense)
- GRB 121117A: GROND confirmation of the UVOT afterglow candidate
- IPN Triangulation of GRB 121118A
- Swift-BAT trigger 538575 is not astrophysical
- GRB 121117A: Swift/UVOT Observations
- GRB 121117A: Swift-XRT refined Analysis
- GRB 121117A: MASTER prompt optical limit
- GRB 121117A, Swift-BAT refined analysis
- GRB 121117A: ROTSE-III Optical Limits
- GRB 121117A: BOOTES-3 early optical upper limit
- GRB 121117A: Swift detection of a burst
- Swift trigger 538575: Magellan Observations
- Fermi GBM trigger 121115.186 is not a GRB
- Trigger 538084: Swift detection of XTE J1739-302
- GRB 121108A: Swift-XRT refined Analysis
- GRB 121108A: Swift/UVOT Upper Limits
- GRB 121108A, Swift-BAT refined analysis
- GRB 121108A: Xinglong TNT upper limit
- GRB 121108A: Enhanced Swift-XRT position
- GRB 121108A : Lulin/TRIPOL2 Optical Limits
- GRB 121108A: Optical observations
- GRB 121108A: MITSuME Ishigakijima upper limits
- GRB 121108A: Weihai observatory optical observations
- GRB 121108A: MASTER early prompt optical limit
- GRB 121108A: TAROT Calern observatory optical observations
- GRB 121108A: Swift detection of a burst
- GRB 121031A: Fermi GBM detection
- GRB 121028A: Swift/UVOT Upper Limits
- GRB 121031A, Early peak observed with Swift-BAT
- GRB 121102A: Swift/UVOT Upper Limits
- GRB 121031A: Swift/UVOT Upper Limits
- GRB 121031A: Swift-XRT refined Analysis
- GRB 121102A: Enhanced Swift-XRT position
- GRB 121031A: Enhanced Swift-XRT position
- GRB 121102A: Swift-XRT refined Analysis
- GRB 121102A: Swift-BAT refined analysis
- GRB 121025A: Confirmation of the X-ray afterglow
- GRB 121029A Suzaku WAM observation of the prompt emission
- GRB 121102A : a long GRB detected by INTEGRAL
- GRB 121102A: Swift detection of a burst
- GRB 121027A: sub-mm upper limit
- GRB 121031A: Swift-BAT refined analysis
- GRB 121031A: Prompt enhanced Swift-XRT position
- GRB 121031A: Swift detection of a burst
- Swift Quick-look and HEASARC are back online
- GRB 121027A: Swift/UVOT Possible Detection
- GRB 121024A: LOAO RIzY Observation
- GRB 121027A: X-shooter redshift confirmation
- GRB 121027A - Gemini South spectroscopy
- GRB 121024A: SMARTS optical/IR afterglow observations
- GRB 121028A: near-IR observations at Calar Alto
- GRB 121027A: GROND Confirmation of Rebrightening
- GRB 121029A: Fermi GBM detection
- GRB 121028A: RAPTOR Limits During Gamma-Ray Emitting Interval
- Swift Quick-look and HEASARC will be offline for due to hurricane Sandy
- GRB 121027A: MASTER early prompt optical limit
- GRB 121027A: Swift-XRT refined Analysis
- GRB 121027A: Brightening IR counterpart
- GRB 121028A: Swift-XRT refined Analysis
- GRB 121028A: Enhanced Swift-XRT position
- GRB 121028A: Swift-BAT refined analysis
- GRB 121027A: Enhanced Swift-XRT position
- GRB 121028A: MITSuME Okayama Optical upper limits
- GRB 121028A: Faulkes Telescope North observations
- GRB 121028A: Swift detection of a burst
- GRB 121011A: optical observations
- GRB 121027A: nIR afterglow candidate with AAT
- GRB 121027A: Swift-BAT refined analysis
- GRB 121025A: Swift-XRT observation
- GRB 121027A: MAXI/GSC detection 40 minutes after the Swift Trigger
- GRB 121027A: Swift detection of a burst
- Swift Quick-look and HEASARC will be offline for 24 hours this weekend
- GRB 121024A: optical observations
- GRB 121024A: EVLA Detection
- Swift-BAT trigger 536502 is not astrophysical
- GRB 121024A: Swift/UVOT Observations
- GRB 121024A: CARMA 3mm Detection
- GRB 121024A: Swift-BAT refined analysis
- GRB 121024A: GMG optical observation
- GRB 121024A: MITSuME Ishigakijima upper limits
- GRB 121024A: MITSuME Okayama Optical upper limits
- GRB 121025A: MAXI/GSC detection
- GRB 121024A: Enhanced Swift-XRT position
- GRB 121024A: PAIRITEL NIR Detection
- GRB 121024A: Swift-XRT refined Analysis
- GRB 121024A: GROND Detection of the Optical/NIR Afterglow
- GRB 121024A: VLT/X-shooter redshift
- Skynet PROMPT/Dolomiti observations of GRB121024A
- GRB 121024A: BOOTES-1B optical detection
- GRB 121024A: TAROT Calern observatory optical detection of a bright counterpart
- GRB 121024A: Swift detection of a burst with an optical counterpart
- Swift Trigger 536502 is likely a noise fluctuation in coincidence with SAX J1818.6-1703
- GRB 121011A: early optical light curve
- GRB 121017A: Swift/UVOT Upper Limits
- GRB 121017A: Swift-XRT refined Analysis
- GRB 121017A: GROND Observations
- GRB 121017A: Swift-BAT refined analysis