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"2380 results found.
- GRB260511B: MAO/AZT-22 optical observations
- GRB 260511A: SVOM/VT optical observations
- GRB 260511B: LCO optical observations
- GRB 260511B: GOTO optical counterpart detection
- GRB 260511B: Xinglong 2.16m/BEFOSC redshift confirmation
- GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
- GRB 260511B: SVOM/VT optical observations
- GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 260510B: EP-FXT follow-up observation
- GRB 260510C: Fermi GBM Observation
- GRB 260511A: REM near-infrared detection
- GRB 260511B: AstroSat CZTI detection
- GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
- GRB 260511B: NuSTAR detection of prompt emission
- GRB 260511A: NuSTAR detection of prompt emission
- GRB 260511B: Fermi GBM Detection
- GRB 260511B: SVOM/VT optical observation with VHF data
- GRB 260511B: TRT optical observation
- GRB 260510B: SVOM/ECLAIRs refined analysis
- GRB 260511B : MITSuME Akeno optical afterglow candidate detection
- GRB 260511A: Fermi GBM Detection
- GRB 260511B SVOM/C-GFT optical counterpart detection
- GRB 260511A: UTGO H50 optical afterglow observation
- GRB 260510C: AstroSat CZTI detection
- GRB 260511B: SVOM detection of a burst
- GRB 260510C: EP-FXT follow-up observation
- GRB 260510C: SVOM/VT optical counterpart confirmation
- GRB 260511A: SVOM/VT optical observation with VHF data
- GRB 260511A: KAIT optical afterglow observations
- GRB 260511A: LCO optical afterglow detection
- GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
- GRB 260511A: TRT optical counterpart detection
- GRB 260511A: SVOM detection of a bright burst
- GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
- GRB 260510B: SVOM/VT optical upper limits
- GRB 260510C: SVOM/VT optical upper limits
- GRB 260510C: MAXI/GSC detection
- Fermi GBM Sub-Threshold Detection of GRB 260510B
- GRB 260510B: GOTO early upper limit
- GRB 260510C: SVOM detection of a burst
- GRB 260510B: LCO optical upper limits
- GRB 260510B: SVOM detection of a burst
- GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
- GRB 260509A: LCO optical observations
- SVOM GRB 260509A: MASTER-OAFA optical observation
- GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
- GRB 260509A: SVOM/VT optical candidate with VHF data
- GRB 260509A: LCO optical counterpart detection
- GRB 260509A: GOTO optical counterpart candidate
- GRB 260509A: SVOM detection of a burst
- EP260507a: SVOM/VT optical observations
- GRB 260504B: AstroSat CZTI detection
- GRB 260504B: SVOM/ECLAIRs refined analysis
- GRB 260430B: Glowbug gamma-ray detection
- GRB 260504B: SVOM/VT optical upper limits
- GRB 260421B: radio observation with the VLA
- Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
- Konus-Wind detection of GRB 260504B (short/hard)
- GRB 260504B: GECAM-B detection
- GRB 260504C: SVOM/GRM observation of short GRB
- GRB 260504B: SVOM/GRM spectral analysis
- GRB 260504B: SVOM/MXT refined analysis and potential detection
- GRB 260502A: SVOM/GRM observation of a short GRB
- GRB 260503A: SVOM/GRM observation of a GRB
- GRB 260504B: REM optical/NIR observations
- IPN triangulation of GRB 260429A
- IPN triangulation of GRB 260428A
- GRB 260504B: AST3-2 i-band upper limit
- GRB 260504B: LCO z-band upper limit
- SVOM GRB 260504B: MASTER-OAFA optical observations
- GRB 260504B: SVOM detection of a short burst
- SVOM/GRM observation of a bright burst from SGR 1E1841-045
- IPN triangulation of a bright burst from SGR 1E1841-045
- GRB 260429A: SVOM/GRM observation of a short burst
- GRB 260424B: AstroSat CZTI detection
- GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
- GRB 260428A: GECAM-B detection of a possible long duration Type I burst
- GRB 260424B: Glowbug gamma-ray detection of a short burst
- GRB 260424B: COLIBRÍ optical upper limit
- Konus-Wind detection of GRB 260424B
- IPN triangulation of GRB 260424B (short)
- GRB 260424B: SVOM/GRM detection of a short burst
- GRB 260401A: cubesat Avion detection
- GRB 260421B: Kilonova-Catcher optical afterglow detection
- GRB 260421B: Insight-HXMT/HE detection
- GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
- GRB 260421B: SVOM/ECLAIRs refined analysis
- EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
- GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
- GRB 260421B: SVOM/GRM observation
- GRB260421B: J band upper limit by SYSU 80cm infrared telescope
- GRB 260421B: EP-FXT follow-up observation
- GRB 260421B: LCO optical counterpart detection
- GRB 260421B: Fermi GBM Observation
- GRB 260412A: SVOM/ECLAIRs refined analysis
- GRB 260421B: SVOM/VT optical observations
- GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
- GRB 260421B: BOOTES-7 early optical afterglow detection
- GRB 260421B: LCO optical afterglow confirmation
- GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart