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"- GRB240809A: Liverpool Telescope optical follow-up observations
- GRB 240810A: Fermi GBM Final Real-time Localization
- GRB 240809A: REM detection of the optical afterglow
- GRB 240809A: Bassano Bresciano Observatory optical observations
- Konus-Wind detection of GRB 240807A (a counterpart of EP240807a)
- GRB 240809A: Conclusive redshift from VLT
- Fermi-LAT gamma-ray observations of IceCube-240808A
- GRB 240809A: KAIT optical observations
- GRB 240808A: AstroSat CZTI detection
- GRB 240809A: GIT afterglow observations
- GRB 240809B: MAXI/GSC detection
- GRB 240809A: Swift/UVOT Detection
- GRB 240809A: Tentative redshift from NOT
- GRB 240809A: Swift-XRT refined Analysis
- IPN triangulation of GRB 240807A / EP 240807a
- LIGO/Virgo/KAGRA S240807h: Updated Sky localization and EM Bright Classification
- X-ray Transient EP240807a: PRIME near-infrared upper limits
- Swift GRB 240809A: Global MASTER-Net observations report
- GRB 240809A: JinShan optical observations
- GRB 240809A: Enhanced Swift-XRT position
- GRB 240809A: Skynet & Photon Ranch Optical Afterglow Observations
- GRB 240809A: SVOM/GRM observation
- GRB 240808A: SVOM/GRM observation
- GRB 240807A: SVOM/GRM observation
- GRB 240809A: Swift detection of a burst with a bright optical counterpart
- EP-WXT trigger 01709018832: SVOM/C-GFT observations of the star flare
- EP240807a: STEP/T80S optical limits
- GRB 240807B: AstroSat CZTI detection of a short burst
- IceCube Alert 240808.27: Global MASTER-Net observations report
- EP EP240807a: Global MASTER-Net observations report
- EP EP240806a: Global MASTER-Net observations report
- IceCube-240808A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 240801A: GRBAlpha detection
- GRB 240807B: Fermi GBM Final Localization
- GRB 240710B: VZLUSAT-2 detection
- GRB 240805A: ATCA Radio Upper Limits
- Fermi trigger No 744761058: Global MASTER-Net observations report
- EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
- S240807h: Identification of a GW compact binary merger candidate
- EP-WXT trigger 01709018832: KAIT optical observations of the star flare
- EP240802a/GRB240802A: KAIT optical upper limit
- GRB 240720B: VZLUSAT-2 detection
- GRB 240710A: VZLUSAT-2 detection
- EP240806A: Liverpool Telescope optical follow-up observations
- The EP-WXT trigger 01709018832 on August 7th is likely a flaring star
- GRB 240807A: Fermi GBM Final Localization
- EP240807a: EP-WXT detection of a fast X-ray transient
- EP240806a: Gemini North-GMOS spectroscopic redshift of z = 2.818
- GRB 240805B: GIT optical upper limit
- EP240806a: KAIT optical observations
- GRB 240805B: Swift-BAT refined analysis
- GRB 240805A: Swift-BAT refined analysis
- Fermi trigger No 744629911: Global MASTER-Net observations report
- EP240804a (GRB 240804B): NOT optical observations
- EP240806a: LCOGT optical counterpart detection
- Konus-Wind detection of GRB 240802A (EP240802a)
- Improved IPN triangulation of GRB 240802A / EP 240802a
- Konus-Wind detection of GRB 240805A
- GRB 240805B Bassano Bresciano Observatory upper limit
- GRB240805A: Fermi GBM Observation
- GRB 240805B: JinShan optical afterglow detection
- GRB 240804B/EP240804a: Correction to the GRB name in GCN 37071
- GRB 240805B: AbAO, CrAO, and Terskol optical upper limits
- Konus-Wind detection of GRB 240804B (a counterpart of EP240804a)
- Fermi Gamma-ray Burst Monitor trigger 240806402/744629911 is not a GRB
- EP240806a: EP-FXT detection of the X-ray emission
- GRB 240626B: VZLUSAT-2 detection
- GRB 240624B: VZLUSAT-2 detection
- GRB 240619C: VZLUSAT-2 detection
- EP 240806A: LCO optical observations
- EP240806a: GSP optical counterpart detection
- EP240806a: EP-WXT detection of a fast X-ray transient
- GRB 240805B: Optical detection with 1.6m Mephisto
- EP240804a: BOOTES-6/DPRT optical detection
- GRB 240805B: NUTTelA-TAO / BSTI Optical Limits
- GRB 240805B: Swift-XRT refined Analysis
- Fermi trigger No 744544656: Global MASTER-Net observations report
- GRB 240805B: Swift/UVOT Upper Limits
- GRB 240805A: Swift/UVOT Upper Limits
- GRB 240805B: BTA optical afterglow candidate
- GRB 240805A: SVOM/GRM observation
- GRB 240805B: Enhanced Swift-XRT position
- GRB 240805B: LCOGT Optical Upper Limits
- Swift GRB 240805B: Global MASTER-Net observations report
- GRB 240805B: JinShan optical upper limits
- EP240801a: BTA BVRI photometry
- Fermi GRB 240805A: Global MASTER-Net observations report
- Swift GRB 240805A: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 744558410/240805574 is not a GRB
- GRB 240805A: Swift-XRT refined Analysis
- EP240804a: GSP detects optical candidate counterpart
- GRB 240805B: Swift detection of a burst
- GRB 240805A: Fermi-LAT detection
- GRB 240805A: INTEGRAL spectral analysis
- EP240801a: Continued optical observations at ZTSh (CraO)
- EP240804a: VLT/X-shooter spectroscopic redshift
- EP240804a: LCOGT optical counterpart detection
- GRB 240805A: A long GRB detected by INTEGRAL
- EP-WXT trigger 00109017646 is not a real source
- EP240804a: NOT optical counterpart detection