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"26810 results found.
- EP260727a: ATCA 10 GHz detection
- GRB 260831A: Fermi GBM Final Real-time Localization
- GRB 260829A: GECAM-B observation of a long burst
- GRB 260825A: SVOM/GRM observation of a long burst
- GRB 260825A: GECAM-B observation
- GRB 260829A: Fermi GBM Detection
- GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
- GRB 260829A: Fermi GBM Final Real-time Localization
- Fermi GBM trigger 809666623/260829141 is not a GRB
- GRB 260818B: Further EP-FXT observation
- GRB 260818B: VLT optical and nIR observations
- GRB 260818B: TNG NIR observations
- MAXI GRB260827.40: Global MASTER-Net observations report
- The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
- GRB 260827A: Fermi GBM Final Real-time Localization
- GRB 260818B: 6 GHz VLA observations
- GRB 260818B: SVOM/VT optical upper limit and continuous observations
- GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
- EP260822a: Global MASTER-Net observations report
- EP Alert 260820.31: Global MASTER-Net observations report
- GRB 260807A: EP-FXT follow-up observations
- GRB 260822A: SVOM/ECLAIRs refined analysis
- GRB 260809A: SVOM/ECLAIRs refined analysis
- GRB 260822A: SVOM/VT optical upper limits
- IceCube Alert 260825A: Global MASTER-Net observations report
- GRB 260825A: Fermi GBM Final Real-time Localization
- GRB 260822A: EP/FXT follow-up observations
- GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
- GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
- EP260822a: EP-FXT non-detection and upper limit
- GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
- GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
- EP260822a: Einstein Probe detection of a fast X-ray transient
- GRB 260822A: LCO optical upper limits
- The EP-WXT trigger 01709287395 is likely a flaring star
- GRB260822B: Fermi GBM Final Localization
- GRB 260822A: GROWTH-India Telescope Upper Limits
- GRB 260822A: GOTO optical upper limit
- GRB 260822A: SVOM detection of a short burst
- GRB 260818B: SVOM/C-GFT optical upper limit
- EP260731a: SVOM/ECLAIRs detection through offline targeted search
- IceCube Alert 260821A: Global MASTER-Net observations report
- The EP-WXT trigger 01709286204 is likely a flaring star
- GRB 260818B: SVOM/GRM observation
- EP detected a brightening of LMXB 1ES 1735-26.9
- GRB260820A: Fermi GBM Final Real-Time Localization
- GRB 260818B: EP-FXT follow-up observation
- GRB 260818A: J-band observations with WINTER
- GRB 260818B: SVOM/ECLAIRs refined analysis
- GRB 260818A: SVOM/ECLAIRs refined analysis
- GRB 260818B: NOT optical upper limits
- GRB 260810A: SVOM/GRM observation
- GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB260818A: EP-FXT follow-up observation
- GRB 260818B: LCO optical upper limits
- GRB 260818B: SVOM detection of a short burst
- SVOM trigger sb26081806 is not a GRB
- EP260806a: SAO RAS multicolor optical observations
- GRB 260818A: LCO optical upper limits
- EP260812a: AbAO optical upper limit
- GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 260818A: SVOM possible detection of a long and faint GRB
- EP260806a: SVOM/ECLAIRs detection through targeted search
- The EP-WXT trigger 01709281429 is likely a flaring star
- EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
- EP260806a: WFST optical observations
- The EP-WXT trigger 01709280562 is likely a flaring star
- The EP-WXT trigger 01709279838 is likely a flaring star
- GRB 260805D: SVOM/GRM detection of a possible magnetar burst
- GRB 260808B: Liverpool Telescope further optical observations
- GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
- GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
- GRB 260813A: Fermi GBM Final Real-time Localization
- EP260812a: NOT and Liverpool Telescope upper limits:
- EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
- EP260812a: SVOM/C-GFT optical upper limit
- EP260812b: COLIBRÍ optical observations
- EP260812b: SVOM/VT optical observation
- GRB 260808A: SVOM/GRM observation
- EP260812b: Einstein Probe detection of an X-ray transient
- EP trigger #01709278129 (EP260812b?): NOT optical counterpart
- Fermi GBM Sub-Threshold Detection of GRB 260809A
- GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
- EP260812a: Einstein Probe detection of an X-ray transient
- GRB 260808B: SVOM/VT optical re-brightening at day 3
- 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 260808A: GECAM-B observation
- GRB 260807A: SVOM/ECLAIRs refined analysis
- GRB260808B: MAO/AZT-22 optical observations
- GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
- GRB 260809A: J-band upper limit with WINTER
- 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
- GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
- The EP-WXT trigger 01709278015 is likely a flaring star
- GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation