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"3296 results found.
- GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
- The EP-WXT trigger 01709266272 is likely a flaring star
- AT2026nik: EP-FXT X-ray counterpart
- EP260527a/GRB 260527A: optical upper limit with Kinder observations
- GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
- GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
- GRB 260527A/EP260527a: Insight-HXMT detection
- EP260526a: SVOM/VT optical upper limits
- EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
- GRB 260527A: CALET Gamma-Ray Burst Monitor detection
- EP260527a/GRB 260527A: EP-FXT follow-up observation
- GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
- Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
- EP260526a: EP-FXT follow-up observation
- EP260527a: COLIBRÍ optical detection
- EP260527a: Einstein Probe detection of a fast X-ray transient
- The EP-WXT trigger 01709266172 is likely a flaring star
- The EP-WXT trigger 01709266147 is likely a flaring star
- EP260526a: LCO optical upper limits
- EP260526a: Einstein Probe detection of a fast X-ray transient
- The EP-WXT trigger 01709266106 is not a real source
- EP01709266106 (EP260526a?): Liverpool Telescope upper limits
- EP-WXT 01709266106: NOT optical upper limits
- EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
- Konus-Wind detection of GRB 260519C
- Konus-Wind detection of GRB 260518A
- GRB 260516D: SVOM/ECLAIRs refined analysis
- GRB 260516D: EP-FXT follow-up observation
- Konus-Wind detection of GRB 260515A
- GRB 260515A: LCO optical counterpart detection
- GRB 260515A: EP-FXT follow-up observation
- EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
- EP260514a: NOT optical counterpart confirmation
- EP260514a: TRT optical counterpart candidate
- Konus-Wind detection of GRB 260512A
- EP260514a: Global MASTER-Net observations report
- EP260514a: Einstein Probe detection of a fast X-ray transient
- EP260512a: LCO optical upper limits
- The EP-WXT trigger 01709262077 is likely a flaring star
- EP260512a: EP-FXT follow-up observation
- EP260507a: Xinglong Schmidt optical counterpart detection
- EP260512a: Global MASTER-Net observations report
- GRB 260511B: further SAO RAS optical observations
- Konus-Wind detection of GRB 260511B
- The EP-WXT trigger 01709262036 is likely a flaring star
- EP260512a: Einstein Probe detection of an X-ray transient
- Konus-Wind detection of GRB 260511A
- GRB 260511B: SAO RAS optical observations
- GRB 260511A: EP-FXT follow-up observation
- GRB 260511B: EP-FXT follow-up observation
- GRB 260510B: EP-FXT follow-up observation
- GRB 260510C: Fermi GBM Observation
- EP260509a: LCO optical upper limits
- GRB 260510C: EP-FXT follow-up observation
- EP260509a: EP-FXT non-detection and upper limit
- EP260509a: Global MASTER-Net observations report
- EP260509a: Einstein Probe detection of an X-ray transient
- EP260507a: REM optical/NIR observations
- EP260507a: refined analysis of the EP-WXT and EP-FXT observations
- GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
- EP260507a: NOT optical observations
- 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
- EP260502a is likely a flaring star
- GRB 260504B: SVOM/VT optical upper limits
- Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
- Konus-Wind detection of GRB 260504B (short/hard)
- GRB 260504B: EP-FXT upper limit
- Konus-Wind detection of GRB 260415C
- Konus-Wind detection of GRB 260411C
- The EP-WXT trigger 01709261576 is likely a flaring star
- GRB 260429B / EP260429a: EP-FXT follow-up observation
- EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
- EP260502a: BOOTES-7: early optical upper limit
- EP260502a: Las Cumbres upper limit
- EP260502a: Einstein Probe detection of an X-ray transient
- EP260429a: Global MASTER-Net observations report
- 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
- EP260430a: Global MASTER-Net observations report
- EP260430a: Einstein Probe detection of an X-ray transient
- EP260429a: EP-WXT detection of a fast X-ray transient
- Konus-Wind detection of GRB 260424B
- The EP-WXT trigger 01709258652: Mondy optical observations
- EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
- EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
- GRB260421B: J band upper limit by SYSU 80cm infrared telescope
- GRB 260421B: EP-FXT follow-up observation
- The EP-WXT trigger 01709260362 is likely a flaring star
- The EP-WXT trigger 01709260314 is likely a flaring star
- EP260416a: Optical follow-up observations with Kinder
- EP-WXT trigger 01709260303: KAIT optical observations
- The EP-WXT trigger 01709260303 is likely a flaring star
- GRB 260417A: SVOM/GRM observation
- EP260321A/AT2026gzf: Optical observation from 1.3m DFOT