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 100909A: Planned XMM-Newton observation
- GRB 100902A : Confirmation of afterglow and re-brightening with CFHT r’-band imaging
- GRB 100909A: Swift target of opportunity observation
- GRB 100909A: a long GRB detected by INTEGRAL
- GRB100906A: detection at 15GHz
- GRB100901A: IAO optical upper limits at 4 days after the burst
- EVLA detection of radio afterglow of GRB100901A
- GRB 100901A: Confirmation of WSRT Radio Detection
- GRB 100901A: CrAO optical observations
- GRB 100906A: RTT150 optical observations
- GRB 100906A: GRAS-007 optical observations
- GRB100906A: R band observations
- Konus-Wind observation of GRB 100906A
- GRB100906A: non-detection at 15GHz
- GRB100906A: Optical observations at IAO
- GRB 100906A: Fermi GBM observation
- GRB 100906A: TLS Monitoring
- GRB 100901A: TLS Detection at 5.5 days
- GRB 100906A: Observations at the Virtual Telescope
- GRB 100906A: Swift-XRT refined analysis
- GRB 100906A: Enhanced Swift-XRT position
- GRB 100906A: Swift/UVOT Observations
- GRB100906A: Errata of MITSuME Okayama about observation time
- GRB100906A: MITSuME Okayama Optical Observation
- GRB 100906A: Ondrejov 65cm observations
- GRB 100906A: TLS Multicolor Observations
- GRB 100905A: Swift/UVOT Upper Limits
- GRB 100901A: TLS observations, SDSS calibration, decay slope
- GRB 100906A: MASTER preliminary prompt+afterglow lc
- GRB 100901A: ISON-NM optical observations
- GRB 100906A: Swift-BAT refined analysis
- GRB 100906A: UKIRT zYJHK Observation
- GRB 100906A: MASTER preliminary polarization prompt light curve
- GRB 100906A: Gemini-N/GMOS redshift
- GRB 100906A : Faulkes Telescope North optical observations
- GRB 100906A: MASTER early OT observations
- GRB 100906A: Swift detection of a burst with an optical afterglow
- GRB 100829A: MASTER optical observations
- GRB100905A: Optical upper limits at IAO
- GRB100905A: MITSuME Okayama optical upper limits
- GRB 100905A: Swift-XRT refined analysis.
- GRB 100905A: UKIRT zJHK Observation
- GRB 100901A: Possible WSRT Radio Detection
- GRB100905A: 1.5m OSN upper limit
- GRB 100905A: Enhanced Swift-XRT position
- GRB 100905A: Swift-BAT refined analysis
- GRB100904A: BOOTES-3 Upper Limit
- GRB 100905A: MASTER Prompt Optical Observations
- GRB 100905A: Faulkes Telescope North observations
- GRB 100905A: Swift detection of a burst
- Optical observations of GRB 100901A
- GRB10901A: Murikabushi telescope observation at 3 days after the burst
- GRB 100901A: Submm observations from SMA
- GRB 100902A: UKIRT JK Observation
- GRB 100902A: GROND observations; afterglow candidate
- GRB 100901A: UKIRT zYJHK Observation
- GRB 100904A: Swift-BAT refined analysis
- GRB100902A: Optical upper limits at IAO
- GRB10901A: Optical observations at IAO
- Konus-Wind observation of GRB 100829A
- GRB 100904A: Swift detection of a burst
- GRB 100902A: Swift-BAT refined analysis
- GRB 100901A: optical observation at Mt.Terskol
- 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