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"37076 results found.
- EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- GRB 260715A: cubesat Avion detection
- GRB 260709A: cubesat Avion detection
- GRB 260708A: cubesat Avion detection
- SN 2026stf / GRB 260708A: ATLAS forced photometry
- GRB 260730B: Glowbug gamma-ray detection
- GRB 260805C: Glowbug gamma-ray detection
- GRB 260805B: Glowbug gamma-ray detection
- Fermi GRB 260805A: Global MASTER-Net observations report
- GRB 260805B: Fermi GBM Final Localization
- GRB 260804A: Glowbug gamma-ray detection
- GRB 260805B: BALROG localization (Fermi Trigger 807622617 / GRB 260805484)
- GRB 260805A: Fermi GBM Final Localization
- AT 2026wki: EP/FXT follow-up observations
- GRB 260730B: CALET Gamma-Ray Burst Monitor detection
- GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
- GRB 260804A: Fermi GBM Final Real-time Localization
- GRB 260708A: LCO further optical observations show supernova features
- GRB 260803A: Fermi GBM Final Real-time Localization
- Fermi GRB 260802B: Global MASTER-Net observations report
- GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
- GRB 260802A / EP J223759.5+531421: SVOM/VT optical upper limit
- GRB 260802A: SVOM/VT optical upper limits from VHF data
- GRB 260802A: LCO optical upper limits
- GRB 260802B: Fermi GBM Final Localization
- GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- 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 260618B: SVOM/VT continued optical observations indicated a steeper and redder decay
- GRB 260731A: AstroSat CZTI detection of a long burst
- GRB 260730B: AstroSat CZTI detection
- GRB 260730B: NuSTAR detection of prompt emission
- GRB 260727A: SVOM/ECLAIRs refined analysis
- GRB 260726A: SVOM/ECLAIRs refined analysis
- GRB260730A: Fermi GBM Final Localization
- EP260727a: SAO RAS optical observations
- GRB 260727A: AbAO and SAO RAS optical observations
- GRB 260726A: EP-FXT follow-up observations
- GRB 260727A: SVOM/GRM observation
- GRB 260726A: Fermi GBM Observation
- EP260727a: OHP/T193 optical observations
- Konus-Wind detection of GRB 260727A
- GRB 260726A: Liverpool Telescope optical observations
- GRB 260727A: Liverpool Telescope optical upper limits
- GRB 260728A: Fermi GBM Final Localization
- GRB 260727A: EP/FXT follow-up observations
- GRB 260727A: Glowbug gamma-ray detection
- GRB 260726A: J-band upper limit with WINTER
- GRB 260727A: J-band upper limit with WINTER
- GRB 260726A: SVOM/VT optical candidate
- GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
- GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
- GRB 260727A: GOTO early optical upper limit
- GRB 260727A: AstroSat CZTI detection
- GRB 260727A: Kilonova-Catcher optical upper limit
- GRB 260727A: LCO optical upper limits
- GRB 260727B: Fermi GBM Final Real-time Localization
- Fermi GRB 260726A: Global MASTER-Net observations report
- 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
- GRB 260616A: cubesat Avion detection
- GRB 260602B: cubesat Avion detection
- GRB 260601A: cubesat Avion detection
- IPN triangulation of GRB 260706B
- GRB 260718A: SVOM/ECLAIRs refined analysis
- Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
- 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
- Fermi GBM trigger 806384210/260722151 is not a GRB
- 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: EP-FXT follow-up observation
- Fermi GRB 260718A: Global MASTER-Net observations report
- GRB 260718A: LCO optical upper limits
- GRB 260711A: SVOM/GRM observation
- GRB 260710A: SVOM/GRM observation
- GRB 260718A: Fermi GBM Observation
- GRB 260718A : GRANDMA and KNC upper limits
- 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 260714B: SVOM/GRM observation
- GRB 260310A / AT2026fgk: Late-time Chandra Detection
- GRB 260714B: GECAM-B observation of a burst
- GRB 260618B: EP-FXT follow-up observation upper limit
- GRB 260714B: COLIBRÍ optical counterpart candidate
- 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: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
- GRB 260714B: Fermi GBM Final Real-time Localization