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"3775 results found.
- EP Alert 260820.31: Global MASTER-Net observations report
- GRB 260809A: SVOM/ECLAIRs refined analysis
- IceCube Alert 260825A: Global MASTER-Net observations report
- SVOM trigger sb26081806 is not a GRB
- EP260806a: SAO RAS multicolor optical observations
- EP260806a: SVOM/ECLAIRs detection through targeted search
- Fermi GBM Sub-Threshold Detection of GRB 260809A
- GRB 260808B: J-band upper limit with WINTER
- EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
- GRB 260809A: SVOM detection of a faint burst
- EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
- Fermi GRB 260805A: Global MASTER-Net observations report
- Fermi GRB 260802B: Global MASTER-Net observations report
- GRB 260726A: SVOM/ECLAIRs refined analysis
- EP260727a: Einstein Probe detection of an X-ray transient
- Fermi GRB 260726A: Global MASTER-Net observations report
- EP260723a: Liverpool Telescope likely optical counterpart
- Fermi GRB 260718A: Global MASTER-Net observations report
- EP260703a: SVOM/ECLAIRs Upper Limit
- GRB 260714B: Fermi-LAT detection
- EP260713a: Einstein Probe detection of an X-ray transient
- GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
- IceCube Alert 260709A: Global MASTER-Net observations report
- GRB260708B: MAXI/GSC detection
- GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
- EP260703a: EP-WXT detection of a fast X-ray transient
- Fermi trigger No 804552016: Global MASTER-Net observations report
- EP260628a: EP-FXT follow-up observation
- EP260623a: Liverpool Telescope optical observations
- EP260623a: REM optical/NIR afterglow detection
- GRB 260616C: GECAM-B observation of a burst
- Konus-Wind detection of GRB 260616A
- GRB260616C: MAXI/GSC detection
- GRB 260614A: AstroSat CZTI detection
- GRB 260604C: OPD1.6m - GRANDMA observations - detection
- GRB 260531B: Glowbug gamma-ray detection
- Fermi GRB 260601A: Global MASTER-Net observations report
- Fermi trigger No 801900520: Global MASTER-Net observations report
- GRB 260531B: Fermi GBM Final Real-time Localization
- GRB 260531A: MAXI/GSC detection
- GRB 260529A: Fermi GBM Final Real-time Localization
- EP260526a: SVOM/VT optical upper limits
- EP260527a: SVOM/VT optical observation
- Fermi trigger No 801580882: Global MASTER-Net observations report
- Fermi trigger No 801135305: Global MASTER-Net observations report
- GRB 260516D: GROWTH-India Telescope optical detection
- GRB 260515A: CrAO ZTSh BVRI optical observations
- SVOM GRB 260515A: Global MASTER-Net observations report
- GRB 260510C: Glowbug gamma-ray detection
- GRB 260510C: CALET Gamma-Ray Burst Monitor detection
- EP260514a: Global MASTER-Net observations report
- GRB 260511B: further SAO RAS optical observations
- GRB 260510C: Fermi GBM Observation
- GRB 260511A: NuSTAR detection of prompt emission
- GRB 260510C: AstroSat CZTI detection
- GRB 260510C: EP-FXT follow-up observation
- GRB 260511A: KAIT optical afterglow observations
- GRB 260510C: SVOM/VT optical upper limits
- GRB 260510C: MAXI/GSC detection
- GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
- EP260507a: GOTO optical counterpart detection
- EP260507a: Einstein Probe detection of an X-ray transient
- Fermi GRB 260506A: Global MASTER-Net observations report
- SVOM GRB 260504B: MASTER-OAFA optical observations
- EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
- EP260430a: Global MASTER-Net observations report
- Fermi GRB 260421C: Global MASTER-Net observations report
- Fermi GRB 260421B: Global MASTER-Net observations report
- Fermi GRB 260417B: Global MASTER-Net observations report
- EP260417a: Global MASTER-Net observations report
- Fermi GRB 260417A: Global MASTER-Net observations report
- EP260416a: Global MASTER-Net observations report
- Fermi trigger No 797912738: Global MASTER-Net observations report
- GRB 260411B: GOTO optical counterpart candidate
- EP260409a: Global MASTER-Net observations report
- GRB 260404A: Fermi GBM Final Localization
- EP260403a: Mephisto optical upper limits
- GRID detection of GRB 260401A
- EP260405a: Global MASTER-Net observations report
- Fermi trigger No 797039833: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 796931884/260403749 is not a GRB
- GRB 260330B: SVOM/ECLAIRs refined analysis
- GRB 260330B: SVOM/VT optical candidate
- GRB 260402B: GECAM-B observation
- GRB 260402B: Fermi GBM Final Real-time Localization
- GRB 260401A: SVOM/GRM observation
- GRB 260401A: GECAM-B observation
- GRB 260401A: Fermi GBM Observation
- GRB 260401A: NuSTAR detection of prompt emission
- GRB 260401A: CALET Gamma-Ray Burst Monitor detection
- GRB 260401A: MAXI/GSC detection
- EP260329b: Mondy and Assy-Turgen optical upper limits
- GRB 260310A / AT2026fgk: Luminance-band optical follow-up with a 28cm telescope in Daocheng
- EP260321a :Xinglong optical observations
- GRB 260321A: SVOM/ECLAIRs refined analysis
- Fermi GBM Sub-Threshold Detection of GRB 260330B
- GRB 260330B: SVOM detection of a burst
- EP260327a: Global MASTER-Net observations report
- GRB 260310A / AT2026fgk: R- and I-band observations with the PKU 60 cm optical telescope
- IPN triangulation of GRB 260316B