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 170526A: Swift-XRT refined Analysis
- LIGO/Virgo G268556: VERITAS Very-High-Energy Gamma-Ray Observations
- GRB 170524A: RATIR Optical and NIR Observations
- GRB 170526A: Enhanced Swift-XRT position
- GRB 170524B: Swift-XRT observations
- GRB 170526A: Swift detection of a burst
- Konus-Wind observation of GRB 170524B
- GRB 170524B: MASTER-OAFA observations
- GRB 170511A CALET Gamma-Ray Burst Monitor detection
- GRB 170524A: TSHAO and CrAO optical observations
- GRB 170524B: Swift ToO observations
- GRB 170524A: Swift-BAT refined analysis
- GRB 170524B: Swift detection of a burst
- GRB 170524A: Swift/UVOT Upper Limits
- GRB 170524A: D50 optical observation and limit
- GRB 170524A: Swift-XRT refined Analysis
- IPN Triangulation of GRB 170522A
- GRB 170511A: MAXI/GSC detection
- GRB 170524A: Enhanced Swift-XRT position
- GRB 170524A: Swift detection of a burst (or possible new SGR)
- GRB 170522A: LCO McDonald observations
- GRB 170522A: Swift-XRT observations
- GRB 170522A: Global MASTER-Net job
- Konus-Wind observation of GRB 170522B
- IPN Triangulation of GRB 170522B (long/intense)
- Konus-Wind observation of GRB 170522A
- GRB 170522A: Tiled Swift observations
- GRB 170522A: Fermi-LAT detection
- GRB 170522A: Fermi GBM detection
- GRB 170514A CALET Gamma-Ray Burst Monitor detection
- GRB 170519A: MITSuME Akeno Optical Observation
- GRB 170519A: Watcher optical observations
- GRB 170519A: Continued RATIR Optical and NIR Observations
- GRB 170519A: MITSuME Okayama Optical Observation
- GRB 170519A: NOT optical observations
- GRB 170519A: Redshift from GTC/OSIRIS
- GRB170519A, Swift-UVOT Detection
- GRB 170519A: BOOTES-5/JGT early optical detection
- LIGO/Virgo G284239: DLT40 follow-up observation
- GRB 170519A: KAIT Optical Observations
- GRB 170519A: Swift-XRT refined Analysis
- GRB 170519A: iTelescope T11 optical observations
- GRB 170519A: Swift-BAT refined analysis
- GRB 170519A: Weihai optical observations
- GRB 170510A: LCO Siding Springs early observations
- GRB 170519A: RATIR Optical and NIR Observations
- GRB 170519A: optical observations
- GRB 170519A: Enhanced Swift-XRT position
- GRB 170519A: Swift detection of a burst with an optical counterpart
- GRB 170510A CALET Gamma-Ray Burst Monitor detection
- LIGO/Virgo G277583: UH88/SNIFS classification of ATLAS and PS1 transients
- GRB 170510A: Swift-XRT afterglow detection
- GRB 170516A: Swift-BAT refined analysis
- GRB 170516A: Swift-XRT refined Analysis
- AXP CXOU J164710.2-455216: Fermi GBM observation
- GRB 170516A: Swift/UVOT Upper Limits
- GRB 170516A: Enhanced Swift-XRT position
- GRB 170516A: Swift detection of a burst
- Swift Trigger AXP CXOU J164710.2-455216: MASTER-OAFA observations
- Swift Trigger on AXP CXOU J164710.2-455216
- GRB 170514A: Fermi GBM detection
- GRB 170510A: AstroSat CZTI(Veto) detection
- Fermi GBM trigger 516459580/170514541 is not a GRB
- GRB 170510A: Global MASTER Net possible OT observations
- Konus-Wind observation of GRB 170510A
- LIGO/Virgo G275404 and G275659: SkyMapper Follow-up Observations
- LIGO/Virgo G284239: Konus-Wind observations
- GRB 170510A: LCO possible counterpart
- GRB 170510A: Swift-XRT observations
- GRB 170510A: Fermi GBM observation
- LIGO/Virgo G284239: H.E.S.S. very-high energy gamma-ray follow-up
- LIGO/Virgo G284239: MAXI/GSC observations
- GRB 170510A: Tiled Swift observations
- GRB 170510A: Fermi-LAT detection
- Swift Trigger 752193 is not a GRB
- LIGO/Virgo G284239: AstroSat CZTI upper limits
- Trigger 751928: Swift misidentification of Cen X-3
- GRB 170423A: TAROT Reunion observatory optical observations
- IceCube-170506A - IceCube update on a high-energy neutrino candidate event
- Swift XRT observations of GRB 170424A
- LIGO/Virgo G284239:SVOM/Mini-GWAC observations of the initial skymap
- LIGO/VIRGO G284239: Fermi GBM Upper Limits
- LIGO/Virgo G284239: HAWC follow-up
- LIGO/Virgo G284239: MASTER automatic follow up and synchronous observations
- LIGO/Virgo G284239: Fermi-LAT search for a high-energy gamma-ray counterpart
- LIGO/Virgo G284239: TZAC TAROT network observations with TRE/TCA/TCH
- GRB 170428A CALET Gamma-Ray Burst Monitor detection
- LIGO/Virgo: G284239 ANTARES search
- LIGO/Virgo G284239: Swift/BAT data search
- LIGO/Virgo G284239: AGILE GRID observations
- LIGO/Virgo G284239: INTEGRAL search for a prompt gamma-ray counterpart
- LIGO/Virgo G284239: AGILE MCAL Observations
- LIGO/Virgo G284239: IceCube neutrino observations
- LIGO/Virgo G284239: Identification of a GW Burst Candidate
- GRB 170428A: GTC spectroscopic redshift of candidate host galaxy
- GRB 170428A: 15 GHz upper limits from AMI
- Swift Trigger 748858: 15 GHz upper limits from AMI
- LIGO/Virgo G268556: Refined localization from CBC parameter estimation
- GRB 170428A: TNG optical observations
- Short GRB 170428A: MASTER-OAFA final reduction of the optical observations