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 100901A: multicolor photometry at Mt.Terskol
- IPN Triangulation of the very bright GRB 100829A
- GRB 100901A: Lightbuckets Optical Observations
- GRB 100901A: HCT optical observations
- GRB 100902A: 1.5m OSN I-band Upper Limits
- Tentative redshift of GRB100902A from Swift-XRT data
- GRB 100902A: Swift XRT refined analysis
- GRB 100902A: Swift/UVOT Upper Limits
- GRB 100902A: optical observation at Mt.Terskol
- GRB 100901A: optical observation at Mt.Terskol
- GRB 100901A: Kanata Telescope observation of the optical afterglow
- GRB100901A: MITSuME Okayama Optical Observation at 1 day after the burst
- GRB 100902A: Enhanced Swift-XRT position
- GRB 100901A: TLS Observations: Break?
- GRB100901A: Errata of MITSuME Okayama about reference catalog
- GRB 100902A: MASTER Prompt Optical Observations
- GRB 100901A: ISON-NM optical observations
- GRB 100902A: Faulkes Telescope South observations
- GRB 100902A: MASTER Optical Early Limit
- GRB 100902A: Swift detection of a burst
- GRB 100901A: 1.5m OSN BVRI-band observations.
- GRB 100901A: ROTSE-III Detection
- GRB 100901A: MASTER optical flare at 420s discovery
- GRB 100901A: Vega telescope optical afterglow observation
- Swift/UVOT Observations of GRB100901A
- GRB 100901A : HCT optical observations
- GRB 100901A: SARA-N observations
- GRB 100901A: THO optical observations
- GRB100901A: MITSuME Okayama Optical Observation
- GRB 100901A: Swift-XRT Team refined analysis
- GRB 100901A - NOT optical observation
- GRB 100901A: Swift-BAT refined analysis
- GRB 100901A: optical observation at Mt.Terskol
- GRB 100901A: Enhanced Swift-XRT position
- GRB 100901A: optical observation at Mt.Terskol
- GRB 100901A: MASTER power low decay
- GRB 100901A: Gemini-N Redshift
- GRB 100901A: MASTER: the OT brightenning
- GRB 100901A: confirmation of the afterglow
- GRB 100901A: MASTER Optical Early Limits
- GRB 100901A: Faulkes Telescope North afterglow candidate
- GRB 100901A: Swift detection of a burst with an optical afterglow
- Konus-Wind observation of GRB 100826A
- GRB 100829.9: MASTER Optical Limits
- IPN triangulation of GRB 100826A
- GRB100826A: Fermi-LAT Observations
- GRB 100823A: optical upper limit
- GRB 100814A: Maidanak optical observations
- GRB 100823A: optical observations
- GRB 100823A: MAXI/GSC detection
- GRB 100725B: Mondy optical upper limit
- GRB 100725B: Maidanak optical upper limit
- GRB 100823A: Swift/UVOT Evidence for Fading Afterglow Emission
- GRB100807A: R band observations
- GRB100823A : MOA optical observation
- GRB 100823A: Candidate IR afterglow
- GRB 100823A: Swift XRT refined analysis
- GRB 100823A: VLT/X-Shooter spectroscopy
- GRB 100823A - second epoch WHT observations
- GRB 100823A: TNG NIR observations
- GRB 100823: 1.5m OSN I-band observations
- GRB 100823A: Swift/UVOT Upper Limits
- GRB 100823A: WHT observations
- GRB 100823A: Swift-BAT refined analysis
- GRB 100823A: Enhanced Swift-XRT position
- GRB 100823A: Swift detection of a burst
- GRB 100814A: Suzaku WAM observation of the prompt emission
- GRB 100814A: ISON-NM optical observations
- IBAS Alert n. 6057 is not due to a GRB
- EVLA radio afterglow detection of GRB 100814A
- GRB 100814B: Fermi GBM detection
- GRB 100814A: optical observations
- GRB 100816A: Fermi GBM observation (correction to GCN 11124)
- Konus-Wind observation of GRB 100816A
- GRB100816A: MITSuME optical upper limits
- GRB 100816A: 10.4-m GTC redshift confirmation
- GRB 100816A: Fermi GBM observation
- GRB 100816A: VLT and Gemini-N revised redshift
- GRB 100814A : Liverpool Telescope Observations
- GRB 100814A: NOT optical observations
- GRB 100816A: NOT optical observations
- Konus-Wind observation of GRB 100814A
- GRB 100814A : Lulin optical observation
- GRB 100816A : Lulin r'-band observation
- GRB 100816A: Gemini-N spectroscopy
- GRB 100816A: Swift UVOT Observations
- GRB100816A Swift-XRT refined analysis
- GRB 100816A: Swift-BAT spectral lag results
- GRB 100816A: 1.23m CAHA optical observations
- GRB 100816A, Swift-BAT refined analysis
- GRB 100816A: Enhanced Swift-XRT position
- GRB 100816A: Gemini-N imaging
- GRB 100816A: CQUEAN riz-band Detection, Host Galaxy?
- GRB100814A - interesting UVOT lightcurve.
- GRB 100816A: TAROT Calern observatory optical detection
- GRB 100816A: MASTER Optical Limits
- GRB100816A: TNG optical afterglow confirmation.
- GRB 100816A: ROTSE-III Optical Limits
- GRB 100816A: Swift detection of a possibly short burst with optical afterglow
- Swift-BAT trigger 431756 is not a burst