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"- GRB 250813B: SVOM detection of a bright long burst
- LIGO/Virgo/KAGRA S250813k: NED Galaxies in the 4-Update Localization Volume
- LIGO/Virgo/KAGRA S250813k: Updated Sky localization
- EP250812a: Nickel optical upper limit
- GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
- GRB 250812A: NTT spectroscopic redshift z = 2.57
- GRB250812a: STEP/T80S Indication of slow decay of afterglow
- EP250812a: NOT, NTT, and GS observations
- GRB 250812A: Swift/UVOT Detection
- GRB 250813A: Fermi GBM Final Localization
- EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
- EP250812a: Liverpool Telescope upper limits
- EP250812a: SVOM/VT optical counterpart
- EP250812a: refined analysis of the EP-WXT and EP-FXT observations
- IceCube-250813A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 250813.14: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250813k: Identification of a GW compact binary merger candidate
- GRB 250812A: EP-FXT counterpart detection
- GRB 250812A: Swift ToO observations
- GRB 250807B: Swift-BAT refined analysis
- EP 250812a: GOTO optical upper limit
- GRB 250812A: Kilonova-Catcher optical afterglow detection
- EP250812a: Swift-XRT counterpart detection
- Fermi Gamma-ray Burst Monitor trigger 776705265/250812644 is not a GRB
- GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
- EP250812a: Einstein Probe detection of an X-ray transient
- GRB 250812A: SVOM/VT optical afterglow confirmation
- GRB 250812A: Swift-XRT afterglow detection
- GRB 250812A: TRT likely optical counterpart detection
- IceCube-Cascade 250809A: Upper limits from a search for additional neutrino events in IceCube
- GRB 250812A: SVOM detection of a faint long burst
- GRB 250809A: Swift-BAT refined analysis
- Fermi Gamma-ray Burst Monitor trigger 776620220/250811660 is not a GRB
- Fermi-LAT Gamma-ray Observations of IceCube-250804A
- GRB 250807A: Swift-BAT refined analysis
- LIGO/Virgo/KAGRA S250810ck: Updated Sky localization and EM Bright Classification
- GRB 250809A: Swift/UVOT Detection
- LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
- Corrected Swift-XRT Refined Analysis of GRB 250809A
- GRB 250809A: Swift-XRT refined Analysis
- GRB 250807B: SVOM/VT optical observation
- EP250807a: EP-FXT follow-up observation upper limit
- GRB 250809A: LCOGT Optical Upper Limits
- GRB 250702B: Chandra X-ray Detection
- EP250807a: Global MASTER-Net observations report
- Fermi GRB 250808A: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 776449964/250809689 is not a GRB
- GRB 250808A: VLT X-shooter candidate counterpart
- GRB 250809A: Prompt enhanced Swift-XRT position
- GRB 250809A: Swift detection of a gamma ray burst
- GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 250808A: Fermi GBM Observation
- GRB 250808A: Swift-XRT candidate counterpart detection
- GRB 250807A: SVOM/VT optical continued observation
- EP-WXT trigger 01709195487: KAIT confirmation of the stellar flare
- GRB 250808A: SVOM detection of a long burst
- GRB 250808A: Fermi GBM Final Real-time Localization
- Konus-Wind detection of GRB 250807A
- GRB 250807B: Swift/UVOT Detection
- GRB 250807B: Kilonova-Catcher optical afterglow detection
- IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
- GRB 250807A: Swift/UVOT Detection
- GRB 250807A: Swift-XRT refined Analysis
- GRB 250807B: VLT/X-Shooter spectroscopic redshift z = 1.522
- GRB 250806A: SVOM/MXT refined analysis
- GRB 250806A: SVOM/ECLAIRs refined analysis
- EP250807a: NTT z-band optical upper limit
- GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
- GRB 250804B: Insight-HXMT detection
- GRB 250807A: SVOM/GRM observation
- Swift GRB250807.45: Global MASTER-Net observations report
- GRB 250807A: AstroSat CZTI detection of bright long burst
- GRB 250807B: Swift-XRT refined Analysis
- GRB 250806A: NOT z-band upper limit and host galaxy candidate
- GRB 250807B: NTT optical observations
- EP250807a: EP-WXT detection of a fast X-ray transient
- EP 250807.979: GOTO optical upper limit
- EP250807a: COLIBRÍ optical upper limit
- GRB 250807A: SVOM/VT optical observation
- EP250806a: Upper limit from Fermi-GBM Observations
- GRB 250807B: Enhanced Swift-XRT position
- Swift GRB250807.65: Global MASTER-Net observations report
- GRB 250807A: Enhanced Swift-XRT position
- IceCube-Cascade 250804A: Upper limits from a search for additional neutrino events in IceCube
- GRB 250807B: Swift detection of a burst with an optical counterpart.
- GRB 250805A: Kilonova-Catcher optical upper limits
- EP250806a:SVOM/VT refined analysis
- GRB 250805A: Swift/UVOT Upper Limits
- GRB 250806A: Swift/UVOT U-band detection
- EP250806a: Liverpool telescope optical upper limit
- GRB 250807A: Swift detection of a burst with an optical counterpart
- IceCube Alert 250804.84: Global MASTER-Net observations report
- GRB 250806A: EP-FXT observation
- EP#01709198415/EP250806a: Swift-XRT observations
- EP250806a: Global MASTER-Net observations report
- EP250802a: EP-FXT follow-up observation
- EP250806a: refined analysis of the EP-WXT and EP-FXT observations
- EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
- EP250806a: SVOM /VT optical candidate
- GRB 250806A: J-band upper limit from WINTER