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"- 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
- GRB 170428A: DCT Imaging
- GRB 170428A: TAROT La Silla observatory optical observations
- GRB 170428A: RATIR Afterglow Confirmation
- GRB 170428A: GROND detection of the afterglow
- GRB 170428A: Swift/UVOT Upper Limits
- GRB 170428A: Xinglong 2.16-m upper limit and host galaxy candidate
- GRB 170428A: Swift-XRT refined Analysis
- GRB 170428A: Swift-BAT refined analysis
- Konus-Wind observation of GRB 170428A
- GRB 170428A: MASTER-OAFA early optical observations
- Swift Trigger 750337 is probably a noise fluctuation
- GRB 170428A: Swift detection of a short burst
- Swift trigger 750096 - OT candidate
- GRB170426.95 MASTER-Net OT detection
- Swift Trigger 750096 is probably a noise fluctuation
- Swift Trigger 750044 is probably a noise fluctuation
- GRB 170424A: LCO Observations
- Konus-Wind observation of GRB 170424A
- GRB 170419A: Swift/UVOT Upper Limits
- GRB 170424A: Tiled Swift observations
- GRB 170424A: Fermi GBM detection
- GRB 170424A: Fermi-LAT detection
- GRB 170419A: LCO Observations
- GRB 170423A: Fermi GBM detection
- Swift Trigger 748858: AbAO and TSHAO optical observations
- Fermi GBM trigger 514436208/170421123 is not a GRB
- Swift Trigger 748858: TAROT La Silla observatory optical observations
- Swift Trigger 748858: RATIR Optical and NIR Observations
- GRB 170419B, Swift-BAT refined analysis
- GRB 170419B: Zadko observatory - Gingin optical observations
- GRB 170419A: Zadko observatory - Gingin optical observations
- Fermi GBM trigger 514379207/170420463 is not a GRB
- GRB 170419A: Swift-XRT refined Analysis
- GRB 170412A CALET Gamma-Ray Burst Monitor detection
- GRB 170419B: Fermi GBM observation
- GRB 170419A: Swift-BAT refined analysis
- Swift trigger 748858: Swift BAT, XRT, and UVOT refined analysis
- GRB 170419B: Swift detection of a burst
- GRB 170419A: Enhanced Swift-XRT position
- Swift Trigger 748858: MASTER-OAFA early optical observations
- GRB 170419A: Swift detection of a burst
- Swift Trigger 748858: Zadko observatory - Gingin optical observations
- Swift Trigger 748858: a possible GRB
- LIGO/Virgo G275404: DLT40 follow-up observation
- LIGO/Virgo G277583: DLT40 follow-up observation
- GRB 170409A: TAROT Reunion observatory optical observations
- Konus-Wind observation of GRB 170409A
- GRB 170402A: AstroSat CZTI detection
- GRB 170409A: Fermi GBM Observation
- GRB 170409A: Fermi-LAT detection
- GRB 170405A: SMARTS optical/IR afterglow observations
- GRB 170403B CALET Gamma-Ray Burst Monitor detection
- GRB 170317A: SAO RAS optical observations
- GRB170405A, Swift-UVOT Detection
- GRB 170405A, Swift-BAT refined analysis
- GRB 170405A: Etelman observatory optical observations
- GRB 170405A: Swift-XRT refined Analysis
- GRB 170405A: RATIR Optical and NIR Observations
- Konus-Wind observation of GRB 170405A
- GRB 170405A: LCO FTN observations
- Trigger 745966: Swift detection of 4U1850-03
- GRB 170405A: ISON/Terskol optical observations
- GRB 170405A: Watcher optical detection
- GRB 170405A: Redshift from OSIRIS/GTC
- GRB 170405A: TAROT Reunion observatory optical observations
- GRB 170405A: NOT optical observations
- GRB 170405A: Fermi-LAT detection
- GRB 170405A: Fermi GBM observation
- GRB 170405A: Enhanced Swift-XRT position
- GRB 170405A: Swift detection of a burst with an optical counterpart
- LIGO/Virgo G275697: Update on significance from offline analyses