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"23442 results found.
- EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
- GRB 260511A: Glowbug gamma-ray detection
- GRB 260511B: SAO RAS optical observations
- GRB 260510D: Glowbug gamma-ray detection of a likely short burst
- GRB 260511B: FRAM-ORM optical detection
- GRB 260511B: LCO optical counterpart detection
- GRB260511B: MAO/AZT-22 optical observations
- GRB 260511B: LCO optical observations
- GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
- GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 260511B: OSIRIS+/GTC redshift z=2.006
- GRB 260509A: SAO RAS optical observations
- GRB 260511A: REM near-infrared detection
- GRB 260511B: GROWTH-India Telescope optical observations
- GRB 260511B: AstroSat CZTI detection
- GRB 260506B: Glowbug gamma-ray detection
- GRB 260506A: Glowbug gamma-ray detection of a short burst
- GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
- GRB 260511B: SVOM/VT optical observation with VHF data
- GRB 260511B: TRT optical observation
- GRB 260511B : MITSuME Akeno optical afterglow candidate detection
- GRB 260511B SVOM/C-GFT optical counterpart detection
- EP260509a: LCO optical upper limits
- GRB 260511A: UTGO H50 optical afterglow observation
- GRB 260510C: AstroSat CZTI detection
- GRB 260511B: SVOM detection of a burst
- GRB 260510C: SVOM/VT optical counterpart confirmation
- EP260509a: EP-FXT non-detection and upper limit
- 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
- Fermi GBM Sub-Threshold Detection of GRB 260510B
- GRB 260510C: SVOM detection of a burst
- GRB 260510B: LCO optical upper limits
- EP260509a: Einstein Probe detection of an X-ray transient
- GRB 260509A: Liverpool Telescope optical observations
- GRB 260510B: SVOM detection of a burst
- GRB 260509A: LCO optical observations
- SVOM GRB 260509A: MASTER-OAFA optical observation
- GRB 260509A: KAIT optical observations
- GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
- GRB 260509A: SVOM/VT optical candidate with VHF data
- GRB 260509A: LCO optical counterpart detection
- GRB 260509A: SVOM detection of a burst
- GRB 260506B: AstroSat CZTI detection
- EP260507a: REM optical/NIR observations
- EP260507a: refined analysis of the EP-WXT and EP-FXT observations
- EP260507a: COLIBRÍ optical observations
- EP260507a: NOT optical observations
- EP260507a: further Liverpool Telescope observations
- EP260507a: Liverpool Telescope optical upper limits
- EP260507a: GOTO optical counterpart detection
- EP260507a: TRT optical counterpart detection
- EP260507a: Kinder optical counterpart candidate
- EP260507a: LCO optical counterpart
- EP260507a: Einstein Probe detection of an X-ray transient
- GRB 260503A: GECAM-B observation of a burst
- GRB 260430B: Glowbug gamma-ray detection
- GRB 260421B: radio observation with the VLA
- Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
- 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: LCO z-band upper limit
- SVOM GRB 260504B: MASTER-OAFA optical observations
- GRB 260504B: SVOM detection of a short burst
- GRB 260503A: Fermi GBM Final Real-time Localization
- SVOM/GRM observation of a bright burst from SGR 1E1841-045
- IPN triangulation of a bright burst from SGR 1E1841-045
- GRB 260429B / EP260429a: AstroSat CZTI detection
- EP260502a: BOOTES-7: early optical upper limit
- EP260502a: Las Cumbres upper limit
- EP260502a: Einstein Probe detection of an X-ray transient
- GRB 260429A: SVOM/GRM observation of a short burst
- SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
- EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
- GRB 260429B / EP260429a: COLIBRÍ optical upper limit
- EP260429a: LCO optical upper limits
- EP260430a: LCO optical upper limits
- GRB 260430A / EP260430a: COLIBRÍ optical upper limit
- EP260430a: Einstein Probe detection of an X-ray transient
- EP260429a: EP-WXT detection of a fast X-ray transient
- GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
- GRB 260428A: AstroSat CZTI detection
- EP260416a: Mondy and Terskol optical upper limits
- 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 260401A: cubesat Avion detection
- GRB 260424A: AstroSat CZTI detection of a long burst
- EP260321a: Upper limits from ATCA radio observations