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 160121A: TSHAO optical afterglow confirmation
- GRB 160121A: Swift-BAT refined analysis
- GRB 160121A: Enhanced Swift-XRT position
- GRB 160121A: 1.8m MOA optical afterglow detection
- GRB 160117B: RATIR continued observations
- GRB 160117B: TNG spectroscopy and redshift confirmation
- LIGO/VIRGO G184098: Summary of VLA results for iPTF15cyk
- GRB 160121A: MASTER-Amur observations
- GRB 160121A: Swift detection of a burst
- Konus-Wind observation of GRB 160119A
- GRB 160117A: Swift-XRT afterglow detection
- GRB 160119A: VLA Detection
- GRB 160117B: VLA Detection
- GRB 160117B: further RATIR observations
- GRB 160119A: afterglow confirmation from the NOT
- GRB160119A: BOOTES-2/TELMA Early Upper Limits
- GRB 160119A: Swift/UVOT Upper Limits
- LIGO/Virgo G184098: MASTER final result
- GRB 160119A: GROND optical/NIR afterglow observations
- GRB 160119A: RATIR Optical and NIR Observations
- GRB 160117B: RATIR Optical and NIR Observations
- GRB 160119A: Swift-BAT refined analysis
- GRB 160117B: further NOT optical observations of the afterglow
- GRB 160119A: Swift-XRT refined Analysis
- GRB 160119A: Enhanced Swift-XRT position
- GRB 160119A: NOT and GTC afterglow candidate
- GRB 160117B: Early iTelescope observation
- GRB 160119A: Swift detection of a burst
- GRB 160117A: Swift/UVOT Upper Limits
- GRB 151228B: AbAO optical upper limit
- GRB 160104A: ISON-Ussuriysk optical observations
- LIGO/Virgo G211117: Refined localization from CBC parameter estimation
- GRB 160117A: Swift-XRT observations
- GRB 160117B: GROND optical/NIR afterglow observations
- GRB 160117B: VLT/X-shooter spectroscopy
- GRB 160117B: iTelescope T17 optical observations
- GRB 160117B: NOT optical afterglow observations
- GRB 160117B: Swift-XRT refined Analysis
- GRB 160117A: Swift-BAT refined analysis
- GRB 160117B: Swift/UVOT Detection
- GRB 160117B: Enhanced Swift-XRT position
- GRB 160117B: LCOGT-SSO optical observations
- GRB 160117B: MASTER-Amur OT observations
- Konus-Wind observation of GRB 160113A
- GRB 160117B: Swift detection of a burst with optical counterpart
- GRB 160117A: Swift detection of a burst
- LIGO/Virgo G211117: Preliminary VLA observation summary of PS15dpn
- GRB 160106A: CALET Gamma-Ray Burst Monitor detection
- IPN Triangulation of GRB 160113A
- LIGO/Virgo G211117: Further Swift-XRT sources
- Konus-Wind observation of GRB 160104B
- LIGO/Virgo G211117: INAF NOT follow-up of PanStarrs candidates
- Konus-Wind observation of GRB 160102A
- Konus-Wind observation of GRB 151231A
- Konus-Wind observation of GRB 160111A
- IPN Triangulation of GRB 160111A (short/hard)
- GRB 151225A: Correction to the trigger time of GCN 18724
- GRB 160113A: Swift-XRT observations
- GRB 160113A: Fermi GBM detection
- GRB 160113A: Swift ToO observations
- GRB 160113A: iPTF P48 Observations and Optical Transient Candidates
- LIGO/Virgo G184098: Refined localizations from CBC parameter estimation
- Konus-Wind observation of GRB 160107A
- GRB 160104A: Swift/UVOT Detection
- IPN Triangulation of GRB 151231A
- Konus-Wind observation of GRB 151229B
- LIGO/Virgo G211117: Updated FAR estimate based on offline re-analysis
- IPN Triangulation of GRB 151229B (extremely intense/long)
- LIGO/Virgo G184098: Updated FAR estimate
- LIGO/Virgo G211117: Distance estimate from GW data compared to redshift of PS15dpn
- LIGO/Virgo G211117: Swift observations of PS15dpn
- LIGO/Virgo G211117: iPTF Observations of PS15dpn
- LIGO/Virgo G211117: PESSTO classification of MASTER J165420.77-615258
- LIGO/Virgo G211117: VLA follow-up
- GRB 160107A: CALET Gamma-Ray Burst Monitor detection
- GRB 160107A: Fermi GBM observation
- LIGO/Virgo G211117: Pi of the Sky observations
- LIGO/Virgo G211117: VISTA imaging
- GRB 160104A: Continued MITSuME Akeno Optical Observation
- LIGO/Virgo G211117: Subaru Hyper Suprime-Cam follow-up observation
- GRB 160107A: MAXI/GSC detection
- Konus-Wind observation of GRB 160101A
- Konus-Wind observation of GRB 151225A
- IPN Triangulation of GRB 151225A (short/hard)
- LIGO/Virgo G211117: MASTER OT in ESO138-006 galaxy
- LIGO/Virgo G211117: Further Swift-XRT sources
- GRB 160104A: Nishi-Harima MINT Observations
- LIGO/Virgo G211117: Liverpool Telescope classification of EM candidates
- GRB 160104A: Spectroscopic observations from 10.4m GTC
- GRB 160104A: Swift-XRT refined Analysis
- GRB 160104A: Swift-BAT refined analysis
- GRB 160104A: Fermi GBM observation
- GRB 160104A: Mini-GWAC upper limit during prompt emission phase
- GRB 160104A: GWAC upper limit during prompt emission phase
- GRB 160104A: MITSuME Okayama upper limits
- LIGO/Virgo G211117: Summary of Pan-STARRS transients
- GRB 160104A: Xinglong TNT optical observation
- LIGO/Virgo G211117: INAF TNG follow-up of Kanata telescope candidate
- GRB 160104A: Enhanced Swift-XRT position
- GRB 160104A: MASTER early OT detection