GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. See the documentation for help with subscribing to or submitting Circulars.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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"- EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
- GRB241113A: 7DT Optical upper limits
- Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
- Fermi GRB 241223A: Global MASTER-Net observations report
- GRB 241223A: GOTO optical observations summary
- GRB 241105A: JWST photometric observations of the host galaxy
- GRB 241223A: Swift ToO observations
- EP241217a: e-MERLIN radio observations
- GRB 241223A: BALROG localization (Fermi Trigger 756648531 / GRB 241223506)
- GRB 241223A: Fermi GBM Final Real-time Localization
- GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
- The EP-WXT trigger 01709129287 is likely a flaring star
- Fermi trigger No 756447119: Global MASTER-Net observations report
- GRB 241209B: host galaxy detection and GTC/OSIRIS+ spectroscopy
- Fermi Gamma-ray Burst Monitor trigger 756447119/241221175 is not a GRB
- Fermi GRB 241221A: Global MASTER-Net observations report
- GRB 241221A: Fermi GBM Final Real-time Localization
- GRB 241217A/EP241217b: SOAR afterglow detection
- EP241217a: Liverpool Telescope optical upper limit
- EP241021a: VLA radio detection
- GRB 241218A: Mondy AZT-33IK optical upper limit
- EP241217a : Leavitt Observatory optical upper limit
- GRB 241217A/EP241217b: tentative VLT spectroscopic redshift z=1.879
- EP241217a: 1.6m Mephisto multi-band optical observations
- GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
- GRB 241218A: Swift/UVOT Upper Limits
- EP241217a: optical upper limit with the Liverpool Telescope
- GRB 241209B: EP-FXT afterglow detection
- Konus-Wind detection of GRB 241204A (short/hard)
- GRB 241218A: NOT optical upper limits
- GRB 241218A: Swift-BAT refined analysis
- GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
- EP 241217a: NIR detection with P200/WIRC
- EP 241217a: Possible J-band detection with WINTER
- GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
- EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
- GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
- GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
- GRB 241217A / EP241217b: NOT optical upper limits
- GRB 241218A: REM optical upper limit
- GRB 241217A/EP241217b: REM optical/NIR upper limits
- EP241217a: REM optical/NIR upper limits
- GRB 241218a: Liverpool Telescope optical follow-up
- GRB 241217a: Liverpool Telescope optical follow-up
- EP241217a: Liverpool Telescope optical follow-up
- GRB 241218A: Swift-XRT refined Analysis
- EP241217a: NOT optical observations
- EP241217a: GROWTH-India Telescope optical observations
- GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
- EP241119a: 7DT Optical upper limits
- EP241217b: Global MASTER-Net observations report
- GRB 241209A: ATCA radio follow-up observations
- EP241217a: Xinglong optical follow-up observations
- EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
- GRB 241218A: LCOGT Optical Upper Limit
- GRB 241218A: Enhanced Swift-XRT position
- EP241217a: Global MASTER-Net observations report
- GRB 241217A: GMG Optical Upper Limit
- GRB 241218A: Swift detection of a burst
- GRB 241217A : SVOM/VT optical afterglow detection
- GRB 241217A: Swift-XRT afterglow detection
- GRB 241217A: LCO optical upper limit
- GRB 241217A: GRANDMA/TAROT optical upperlimits
- EP241217a: Swift-XRT Detection
- EP241217A: Non-detection from Fermi-GBM Observations
- GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
- EP241217a: Gemini-North spectroscopic redshift z = 4.59
- EP241217a: Kinder optical follow-up observations
- GRB 241214A: GRBAlpha detection
- GRB 241213A (EP241213a): GRBAlpha detection
- GRB 241209D: GRBAlpha detection
- EP241217A: LCO optical observations
- EP241217a: Gemini-North detection of the likely optical counterpart
- EP241217a: EP detection of an X-ray transient
- The EP-WXT trigger 01709129023 is likely a flaring star
- EP241107a: VLA Radio Observation
- GRB 241213A: Swift-BAT refined analysis
- GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
- Konus-Wind detection of GRB 241213A (EP 241213a)
- GRB 241215A: Mondy AZT-33IK optical observations
- GRB 241212A: Swift-XRT observations
- GRB 241214A: SVOM/GRM observation
- The EP-WXT trigger 01709128948 is likely a flaring star
- GRB 241215A: Nanshan/HMT optical upper limit
- GRB 241215A: Montarrenti Observatory optical upper limit
- GRB 241215A: GROWTH-India telescope optical upper limit
- GRB 241215A: A long GRB detected by INTEGRAL
- Integral GRB241215.58: Global MASTER-Net observations report
- The EP-WXT trigger 01709128921 is likely a flaring star
- GRB 241213B: Swift-XRT observations
- GRB 241209D: CALET Gamma-Ray Burst Monitor detection
- GRB 241209B: SVOM/VT optical continuous fading
- EP trigger ID 01709128824 is not a real source
- GRB 241213A: SVOM/VT optical candidate
- GRB 241213B: Tiled Swift observations
- GRB 241213A: Swift/UVOT Upper Limits
- GRB 241213B: CALET Gamma-Ray Burst Monitor detection
- GRB 241213A: Swift-XRT refined Analysis
- GRB 241212A: Fermi GBM detection
- EP241208a: NOT optical upper limits