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.
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/KAGRA S230518h: ATCA follow-up of candidate counterparts
- LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
- LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for Swope candidates: SSS23a, SSS23b and SSS23c
- GRB 230520A: MAXI/GSC detection
- LIGO/Virgo/KAGRA S230518h: ATLAS observations of the skymap
- LIGO/Virgo/KAGRA S230518h: Swope Search and Candidate Counterpart Identification
- GRB 230518A: Fermi GBM Observation
- LIGO/Virgo/KAGRA S230518h: Upper limits from Konus-Wind observations
- LIGO/Virgo S230518h: AGILE/MCAL observations
- GRB 230518A: Swift/BAT-GUANO detection
- LIGO/Virgo S230518h: Swift XRT observations, 8 X-ray sources
- LIGO/Virgo/KAGRA S230518h: Coverage and upper limits from MAXI/GSC observations
- GRB 230518A: Fermi GBM Final Real-time Localization
- Fermi Gamma-ray Burst Monitor trigger 706068974/230518095 is not a GRB
- LIGO/Virgo/Kagra S230518h: NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S230518h: AstroSat CZTI non-detection and upper limits
- LIGO/Virgo/KAGRA S230518h: Upper limits from Fermi-GBM Observations
- LIGO/Virgo S230518h: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230518h: Updated Sky localization and EM Bright Classification
- LIGO/Virgo S230518h: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo S230518h: Upper limits from IceCube neutrino search
- LIGO/Virgo/KAGRA S230518h: Identification of a GW compact binary merger candidate
- GRB 230513A: Zwicky Transient Facility continuous observations of a Fermi Short GRB (Trigger 705709044)
- GRB 230510B: GRBAlpha detection
- Fermi trigger No 706014351: Global MASTER-Net observations report
- GRB 230517A: BALROG localization (Fermi Trigger 706014351 / GRB 230517462)
- Improved IPN triangulation of GRB 230512A
- GRB 230517A: Fermi GBM Final Real-time Localization
- GRB 230510B: Fermi GBM detection
- Fermi trigger No 705952199: Global MASTER-Net observations report
- GRB 230516A: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 230511D (short)
- IPN triangulation of GRB 230512A
- GRB 230513A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705709044)
- GRB 230512A: Nanshan/NEXT non-detection of GRB afterglow candidate
- GRB 230512A: Zwicky Transient Facility non-detection of GRB afterglow candidate
- GRB 230512A: Liverpool Telescope observations
- GRB 230512A: GIT non detection of afterglow candidate
- GRB 230512A: Kitab possible afterglow candidate
- GRB 230512A: GRBAlpha detection
- GRB 230510A: GRBAlpha detection
- GRB 230513A: Fermi GBM Final Real-time Localization
- Fermi trigger No 705565670: Global MASTER-Net observations report
- Fermi-LAT gamma-ray observations of IceCube-230511A
- GRB 230510A: OHP/T193 and OHP/T120 optical observations
- GRB 230512A: Swift-XRT observations
- IceCube-230511A: Upper limits from a search for additional neutrino events in IceCube
- IceCube-Cascade 230511A: Upper limits from a search for additional neutrino events in IceCube
- GRB 230512A: GIT optical follow-up ZTF candidates
- GRB 230512A: Fermi GBM detection
- GRB 230512A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705565670)
- GRB 230430A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 704533643)
- GRB 230511D: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 705537623)
- GRB 230512A: Tiled Swift observations
- GRB 230512A: Fermi-LAT detection
- GRB 230512A: AstroSat CZTI detection
- GRB 230512A: Fermi GBM Final Localization
- GRB 230510A: GIT optical upper limits
- GRB 230510A: LCOGT Optical Upper Limit
- GRB 230511D: Fermi GBM Final Real-time Localization
- GRB 230510A: Swift/UVOT Observations
- IceCube-230511A: IceCube observation of a high-energy neutrino candidate
- GRB 230510B: AstroSat CZTI detection
- GRB 230511C: Fermi GBM Final Localization
- Fermi trigger No 705503315: Global MASTER-Net observations report
- GRB 230511B: Fermi GBM Final Real-time Localization
- Fermi trigger No 705496510: Global MASTER-Net observations report
- GRB 230511A: Fermi GBM Final Real-time Localization
- GRB 230510A: Fermi GBM detection
- Fermi trigger No 705446499: Global MASTER-Net observations report
- GRB 230510A: Gaoyazi/GOT optical upper limit
- GRB 230510B: CALET Gamma-Ray Burst Monitor detection
- GRB 230510A: CALET Gamma-Ray Burst Monitor detection
- GRB 230510A: Nanshan/NEXT optical afterglow detection
- GRB 230510B: MAXI/GSC detection
- GRB 230510B: Fermi GBM Final Real-time Localization
- GRB 230506B: Fermi GBM detection
- GRB 230510A: Swift-XRT refined Analysis
- GRB 230510A: Enhanced Swift-XRT position
- GRB 230506C: Fermi GBM detection
- Fermi trigger No 705413051: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 230510133/705381054 is not a GRB
- GRB 230510A: Swift detection of a burst
- GRB 230510A: Fermi GBM Final Real-time Localization
- GRB 230506B: Swift/UVOT further analysis
- GRB 230506C: T193-OHP MISTRAL tentative redshift
- GRB 230506C: SAO RAS optical observations
- GRB 230307A: JWST second-epoch observations
- IceCube-230506A: Upper limits from a search for additional neutrino events in IceCube
- Fermi-LAT gamma-ray observations of IceCube-230506A
- GRB 230506C: Swift-XRT refined Analysis
- GRB 230506C: Swift-BAT refined analysis
- GRB 230506B: Swift-BAT refined analysis
- GRB 230506C: spectro-imaging observations of the optical afterglow with T193-OHP
- GRB 230506B: LCOGT Optical Upper Limits
- GRB 230506C: Swift/UVOT Upper Limits
- GRB 230506C: NUTTelA-TAO / BSTI Early Optical Limits
- GRB 230506B: Swift-XRT refined Analysis
- GRB 230506C: Swift-XRT analysis
- GRB 230506C: Candidate afterglow observation by D50