GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"- GRB240414A : J-band upper limits from WINTER
- GRB 240414A: Enhanced Swift-XRT position
- GRB 240414A : OHP/T193 second epoch of optical follow-up and afterglow detection
- GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
- LIGO/Virgo/KAGRA S240413p: No Counterparts in DDOTI/OAN Optical Observations
- EP240413A: GOTO optical upper limits
- GRB 240414A: Skynet Optical Afterglow Observations
- Fermi trigger No 734754044: Global MASTER-Net observations report
- Swift GRB 240414A: Global MASTER-Net observations report
- EP240414a: Kinder optical counterpart candidate possibly associated with the galaxy SDSS J124601.99-094309.3
- IPN triangulation of GRB 240410A
- EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
- EP240414a: EP-WXT detection of a fast X-ray transient
- IPN triangulation of GRB 240411A
- Fermi-LAT gamma-ray observations of IceCube-240412A
- GRB 240414A : MITSuME Akeno optical upper limits
- GRB 240414A: Redshift confirmation from GTC/OSIRIS+
- EP240413a: EP-WXT detection of a fast X-ray transient
- GRB 240414A : OHP/T193 redshift determination
- GRB 240414A : OHP/T193 optical counterpart detection
- GRB 240414A: Swift detection of a burst
- LIGO/Virgo/KAGRA S240413p: Updated Sky localization
- LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S240413p: Zwicky Transient Facility observations
- EP240408a: GSP optical upper limit
- GRB 240411B: CrAO/ZTSh optical observations
- GRB 240411B: Kinder observations with Lulin observatory
- LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
- GRB 240411B: HiPERCAM/GTC observation
- IceCube Alert 240412.23: Global MASTER-Net observations report
- GRB 240411B: Swift-BAT refined analysis
- GRB 240411B: Swift-XRT refined Analysis
- IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 240411B: 1.3m DFOT Optical observations
- GRB 240411A: GRBAlpha detection
- GRB 240411B: OHP/T193 optical observations
- GRB 240405A: Glowbug gamma-ray detection
- GRB 240411B: Enhanced Swift-XRT position
- GRB 240411B: LCO optical afterglow detection
- GRB 240411B: Swift detection of a burst
- GRB 240408B: GRBAlpha detection
- GRB 240411A: Fermi GBM Final Real-time Localization
- EP240408A: MASTER optical observations
- EP240408a: GROND detection of a candidate counterpart
- EP240408a: Upper limits from GECAM-B Observation
- EP240408a: Swift follow-up observation
- EP240408a: BOOTES-6/DPRT optical upper limit
- X-ray transient EP240315a: second epoch e-MERLIN radio observations
- GRB 240405A: GRBAlpha detection
- EP240408a: EP-WXT detection of a fast X-ray transient
- Swift Trigger 1220736: detection of 4U 1543-62.
- GRB 240408B: AstroSat CZTI detection
- IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
- Fermi GRB 240408A: Global MASTER-Net observations report
- GRB 240408A: Fermi GBM Final Real-time Localization
- GRB 240407A: BALROG localization (Fermi Trigger 734144396 / GRB 240407042)
- GRB 240402C: CALET Gamma-Ray Burst Monitor detection
- Fermi GRB 240407A: Global MASTER-Net observations report
- GRB 240407A: Fermi GBM Final Real-time Localization
- Fermi-LAT gamma-ray observations of IceCube-240327B
- Fermi-LAT gamma-ray observations of IceCube-240327A
- LXT 240402A/GRB 240402B: rest-frame energetics from Konus-Wind observation
- Fermi GRB 240405B: Global MASTER-Net observations report
- GRB 240405B: Fermi GBM Final Real-time Localization
- GRB 240402C: Glowbug gamma-ray detection
- GRB 240405A: Fermi GBM Final Real-time Localization
- GRB 240402C: GRBAlpha detection
- GRB 240331A: GRBAlpha detection
- LXT 240402A/GRB 240402B: GECAM-C refined analysis
- Swift satellite resumes pointed science observations
- GRB 240403B: Glowbug gamma-ray detection
- GRB 240403A: Glowbug gamma-ray detection
- LXT 240402A/GRB 240402B: Glowbug gamma-ray detection
- X-ray transient LXT 240402A: WFST optical upper limits
- Konus-Wind detection of LXT 240402A/GRB 240402B
- GRB/FXT 240402B: Kinder optical counterpart candidate
- IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
- GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
- GRB 240403A: Fermi GBM Detection
- X-ray transient LXT240402A: AST3-3 optical upper limits
- LXT 240402A: EP-FXT detection of the X-ray afterglow
- Fermi GRB 240404A: Global MASTER-Net observations report
- GRB 240404A: Fermi GBM Final Real-time Localization
- LXT 240402A: MASTER optical observations with AGN in error-box
- GRB 240402B: GWAC-F50A optical upper limit
- GRB 240402B: GECAM-C detection
- X-ray transient LXT 240402A: LEIA detection
- GRB 240403A: BALROG localization (Fermi Trigger 733838255 / GRB 240403498)
- Fermi trigger No 733808041: Global MASTER-Net observations report
- Fermi GRB 240402A: Global MASTER-Net observations report
- GRB 240402A: Fermi GBM Final Real-time Localization
- X-ray transient EP240331a: Kinder optical upper limits
- X-ray transient EP240331A: GRANDMA-Kilonova catcher optical upper limit
- EP240331A: MASTER optical observations
- Transient EP240315a: J-band observations of AT2024eju with WIRC
- X-ray transient EP20240331a: MeerLICHT optical upper limits
- IBAS Alert n.10651 not a GRB
- IceCube-240327B: Upper limits from a search for additional neutrino events in IceCube
- IceCube-240327A: Upper limits from a search for additional neutrino events in IceCube