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"28063 results found.
- GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
- GRB 260806A: CALET Gamma-Ray Burst Monitor detection
- GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
- EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
- GRB 260806A: Glowbug gamma-ray detection
- GRB 260808A: CALET Gamma-Ray Burst Monitor detection
- GRB 260805C: CALET Gamma-Ray Burst Monitor detection
- GRB 260804A: CALET Gamma-Ray Burst Monitor detection
- GRB 260809A: NOT optical observations
- GRB260809A: MAO/AZT-22 optical observations
- GRB260809A: OHP/T193 optical observations
- GRB 260809A: SVOM detection of a faint burst
- GRB 260808B: NOT optical observations
- GRB 260808A: NuSTAR detection of prompt emission
- GRB260808B: OHP/T193 optical observations
- GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
- EP260809a: Einstein Probe detection of an X-ray transient
- GRB 260808B: SVOM/VT optical afterglow confirmation
- GRB 260808C: Fermi GBM Final Real-time Localization
- GRB 260808B: SVOM detection of a faint burst
- GRB 260808A: Fermi GBM Final Real-time Localization
- EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
- GRB 260807A: SVOM possible detection of a faint burst
- IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
- EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
- EP260806a: Einstein Probe detection of an X-ray transient
- GRB 260715A: cubesat Avion detection
- GRB 260709A: cubesat Avion detection
- GRB 260708A: cubesat Avion detection
- SN 2026stf / GRB 260708A: ATLAS forced photometry
- IceCube-260805A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260730B: Glowbug gamma-ray detection
- GRB 260805C: Glowbug gamma-ray detection
- GRB 260805B: Glowbug gamma-ray detection
- GRB 260805B: Fermi GBM Final Localization
- GRB 260804A: Glowbug gamma-ray detection
- GRB 260805A: Fermi GBM Final Localization
- AT 2026wki: EP/FXT follow-up observations
- GRB 260730B: CALET Gamma-Ray Burst Monitor detection
- GRB 260804A: Fermi GBM Final Real-time Localization
- GRB 260803A: Fermi GBM Final Real-time Localization
- GRB 260802B: Fermi GBM Final Localization
- GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
- GRB 260727A: EP-FXT further follow-up observations and candidate afterglow
- GRB 260731A: AstroSat CZTI detection of a long burst
- GRB 260730B: AstroSat CZTI detection
- GRB 260730B: NuSTAR detection of prompt emission
- EP260731a: Einstein Probe detection of an X-ray transient
- GRB260730A: Fermi GBM Final Localization
- EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
- EP260729a: Einstein Probe detection of an X-ray transient
- EP260728a: Einstein Probe detection of a fast X-ray transient
- EP260727a: 1.5m OSN optical counterpart detection
- Konus-Wind detection of GRB 260727A
- GRB 260726A: Liverpool Telescope optical observations
- EP260727a: Liverpool Telescope confirmation of optical counterpart
- GRB 260728A: Fermi GBM Final Localization
- EP260727a: Einstein Probe detection of an X-ray transient
- GRB 260727A: Glowbug gamma-ray detection
- GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
- GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
- GRB 260727A: AstroSat CZTI detection
- GRB 260727B: Fermi GBM Final Real-time Localization
- GRB 260727A: SVOM detection of a bright long burst
- GRB 260726A: SVOM detection of a burst
- GRB 260726A: Fermi GBM Final Real-time Localization
- EP260723a: further EP-FXT follow-up observation
- EP260725a: EP-FXT follow-up observation and association with a bright flaring star
- EP260725a: EP-WXT detection of an X-ray transient
- GRB 260616A: cubesat Avion detection
- EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
- GRB 260602B: cubesat Avion detection
- GRB 260601A: cubesat Avion detection
- EP260723a: EP-FXT follow-up observation
- EP260723a: Liverpool Telescope likely optical counterpart
- EP260723a: EP-WXT detection of a fast X-ray transient
- GRB 260723A: Fermi GBM Final Localization
- IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
- Konus-Wind detection of GRB 260721A
- GRB 260722A: Fermi GBM Final Real-time Localization
- IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 260721A: NuSTAR detection of prompt emission
- Konus-Wind detection of GRB 260714B
- GRB 260705A: Retraction of optical counterpart
- GRB 260714B: Insight-HXMT/HE detection
- GRB 260718A: SVOM/VT optical upper limits
- GRB 260718A: SVOM/VT optical upper limits from VHF data
- GRB 260718A: SVOM detection of a burst
- GRB 260310A / AT2026fgk: Late-time Chandra Detection
- sb26071506: SVOM detection of a X-ray transient
- GRB 260715A: Fermi GBM Final Real-time Localization
- GRB 260710A: AstroSat CZTI detection
- GRB 260709A: AstroSat CZTI detection
- GRB 260714B: AstroSat CZTI detection
- GRB 260714B: Fermi-LAT detection
- GRB 260714B: Fermi GBM Detection
- GRB 260714B: Fermi GBM Final Real-time Localization
- IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
- GRB 260706A: ATCA detection of possible radio counterpart
- GRB 260714A: Fermi GBM Final Real-time Localization