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 130505A: Tautenburg afterglow observations
- GRB 130427A: Tautenburg afterglow observations
- Refined IPN Triangulation of GRB 130502B
- GRB 130427A: RHESSI observations
- GRB 130505A, Swift-BAT refined analysis
- GRB 130504C: further Swift-XRT observations
- Konus-Wind observation of GRB 130504C
- GRB 130505B: MAXI/GSC detection
- GRB 130505A: optical observations
- GRB 130504C: Swift-XRT observations
- GRB 130504C: Fermi GBM detection
- GRB 130427A: optical observations in CrAO
- GRB 130502A: optical upper limit
- GRB 130505A: E_iso record retraction
- GRB 130427A: correction to GCN 14487
- GRB 130505A: correction to GCN 14575
- GRB 130505A: Swift-XRT refined Analysis
- GRB 130505A: Largest E_iso ever measured
- Konus-Wind observation of GRB 130505A
- GRB 130504C: Fermi-LAT detection of a burst
- Swift/UVOT observations of GRB130505A
- GRB 130505A: iTelescope T12 optical observations
- GRB 130505A: Xinglong TNT optical observations
- GRB 130505A; Weihai optical observations
- GRB 130505A: Enhanced Swift-XRT position
- GRB 130505A: MITSuME Okayama Optical Observation
- GRB 130505A - Gemini-N/GMOS redshift determination
- GRB 130505A: MAXI/GSC detection
- Konus-Wind observation of GRB 130504B
- GRB 130504A: IAC80 optical candidate
- GRB 130505A: Swift detection of a burst with optical afterglow
- GRB 130504A: MITSuME Okayama upper limits
- IPN Triangulation of GRB 130504B
- GRB 130504B: Fermi GBM detection
- GRB 130504A: Bassano Bresciano Observatory optical upper limit
- GRB 130504A: Enhanced XRT position
- GRB 130502B: Suzaku WAM observation of the prompt emission
- GRB 130504A: Swift/UVOT Upper Limits
- GRB 130502B: Swift-XRT refined Analysis
- GRB 130504A, Swift-BAT refined analysis
- Swift-XRT X-ray afterglow candidate for GRB 130504A (BAT trigger 555096)
- GRB 130502B: possible TNG counterpart
- Trigger 555096: Swift detection of a possible burst
- GRB 130502A: Swift-BAT refined analysis
- GRB 130427A: Non-observation of VHE emission with HAWC
- GRB130502A: MASTER-Net optical observations
- GRB 130502A: Swift-XRT refined Analysis
- IPN Triangulation of GRB 130502B
- GRB 130502A: Fermi GBM detection
- GRB 130502B: Swift/UVOT Upper Limits
- GRB 130502A: Swift/UVOT Upper Limits
- Konus-Wind observation of GRB 130502B
- GRB 130502B: P60 Observations
- GRB 130502B Swift-XRT observations
- GRB 130502A: RATIR Optical and NIR Observations
- GRB 130427A: Pan-STARRS 1 optical observations
- GRB 130418A: TNG NIR observations
- GRB 130502A: Enhanced Swift-XRT position
- GRB 130502A: OSN and IAC80 I-band observations
- GRB 130427A: MITSuME Ishigakijima Optical Observation after 5 days
- GRB 130502A: z-band observations from GTC
- GRB 130502B: Fermi LAT Detection
- GRB 130502A: TNG candidate counterpart
- GRB 130502B: Fermi GBM detection of a burst
- GRB 130502A: T100 Observations
- GRB 130502A: Swift detection of a burst
- GRB 130427A: Predictions about the occurrence of a supernova
- GRB 130427A: KAIT optical observations
- GRB 130425A: Suzaku WAM observation of the prompt emission
- GRB 130427A: SARA-N optical observations
- GRB 130427A: VLA 20 GHz detection
- GRB 130427A: ABT optical observations
- GRB 130427A: High-energy neutrino search
- GRB 130427A: GMRT radio detection
- GRB 130427A: Continued GMG optical observations
- GRB 130427A: Nishi-Harima Optical Spectroscopic Observations
- GRB 130427A: photo-z of possible SDSS host galaxy
- GRB 130427A: high energy gamma-ray detection by AGILE
- GRB 130427A: Continued RATIR Optical and NIR Observations
- GRB 130427A: MITSuME Ishigakijima Optical Observation after 2 days
- Swift-BAT trigger 554135 is noise
- GRB 130427A: Challis Observatory optical observations
- GRB 130427A: Continued Skynet/PROMPT Observations
- GRB 130427A: further GMG observations
- GRB 130427A: Fermi-LAT refined analysis
- GRB 130427A: SARA-N detection
- GRB 130427A: Continued RATIR Optical and NIR Observations
- GRB 130427A: CrAO RT-22 36 GHz observation
- GRB 130418A: Bassano Bresciano Observatory lightcurve analisis
- GRB 130427A in the Ep,i - Eiso plane
- GRB 130427A: Improved Swift-XRT analysis
- GRB 130425: MASTER-Net optical observations
- GRB 100728A: GROND host detection and X-shooter redshift
- GRB 130427B: MITSuME Ishigakijima upper limits
- GRB 130427A: MITSuME Okayama and Ishigakijima Optical Observation after 1 day
- GRB 130427A: Skynet/PROMPT Observations
- GRB 130427B: RATIR Optical and NIR Observations
- GRB 130427A: Nishi-Harima NIR Observations
- GRB 130427A: CARMA 3mm observations
- GRB 130427B: Tentative VLT/X-shooter redshift