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"- Swift Trigger 1282245 is not a GRB
- GRB 250116A: Fermi-LAT detection
- GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
- GRB 250114B: Swift-XRT afterglow detection
- GRB 250114B: SVOM/VT upper limit
- Fermi Gamma-ray Burst Monitor trigger 758659047/250115776 is not a GRB
- EP250108a: MeerKAT radio upper limit
- LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
- GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
- LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
- Konus-Wind detection of GRB 250113A
- IPN triangulation of GRB 250113A
- GRB 250114B: Liverpool Telescope optical upper limit
- LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
- GRB 250114B : MITSuME Akeno optical afterglow candidate detection
- GRB 250114B: Swift-XRT observations
- GRB 250114A: LCO optical counterpart detection.
- GRB 250114B: OHP/T193 optical upper limit
- GRB 250114A: GRANDMA/TAROT optical afterglow detection
- GRB 250114A: Swift-XRT refined Analysis
- Integral GRB250114.55: Global MASTER-Net observations report
- GRB 250114A: LCOGT optical afterglow i-band detection
- GRB 250114B : GIT optical upper limit
- GRB 250114B: Swift ToO observations
- EP250111a: SAO RAS optical upper limit
- LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
- GRB 250114B: a short GRB detected with INTEGRAL
- EP250108a: correction to GCN 38908
- GRB 250114A: Enhanced Swift-XRT position
- GRB 250113A: INTEGRAL/SPI-ACS detection
- GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
- GRB 250114A: REM detection of the optical and NIR counterpart
- LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
- Swift GRB250114A: Global MASTER-Net OT detection
- GRB 250114A: LCO optical observations
- GRB 250114A: TRT optical observations
- Swift GRB 250114A: Global MASTER-Net observations report
- GRB 250114A: Swift detection of a burst with an optical counterpart
- GRB 250101A: Terskol Zeiss-2000 optical observations
- EP250108a / AT 2025kg: SAO RAS optical observations
- EP241021a: SMA radio observation
- GRB 250113A: SVOM/GRM observation of a long burst
- GRB 250107A: VZLUSAT-2 detection
- EP250109b: optical upper limits with the Liverpool Telescope
- GRB 250109A / EP250109a: GRBAlpha detection
- GRB 250107D: GRBAlpha detection
- GRB 250106A: Swift-XRT afterglow detection
- Fermi trigger No 758442826: Global MASTER-Net observations report
- EP250111a: KAIT optical observations
- GRB 250109A / EP250109a: Mephisto optical upper limits
- EP250108a: Mephisto detection
- EP250111a: Mondy optical observation
- EP250108a / AT 2025kg: LCO optical observations
- EP250111a: Global MASTER-Net observations report
- EP250111a: Swift/XRT detection and fading
- EP250108a / AT 2025kg: Swift UVOT detections
- EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
- EP250108a: optical follow-up observations with the Liverpool Telescope
- EP250111a: NOT likely optical counterpart
- EP250111a: a new X-ray transient detected by Einstein Probe
- EP250109a/GRB 250109A:SVOM/VT optical counterpart
- GRB 250101B: Fermi GBM Observation
- EP250108a: further NOT optical observations
- GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
- GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
- GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
- GRB 250108A: Swift/XRT afterglow fading
- GRB 250107D: CALET Gamma-Ray Burst Monitor detection
- GRB 250107C: CALET Gamma-Ray Burst Monitor detection
- Konus-Wind detection of GRB 250107C
- LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
- LIGO/Virgo/KAGRA S250109f: Updated Sky localization
- LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
- EP-WXT trigger EP250108a：Xinglong optical follow-up observations
- GRB 250101A: CMO RC-500 optical observations
- EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
- EP250108a: EP-FXT follow-up observation
- GRB 250109A: Fermi GBM Observation
- The EP-WXT trigger 01709130111 is likely a flaring star
- EP250108a: NOT optical observations
- EP-WXT trigger EP250109a：Xinglong optical follow-up observations
- GRB 250109a: GMG Optical Upper Limit
- EP250109a: Swift/UVOT non-detection
- Konus-Wind detection of GRB 250107D (short/hard)
- IPN triangulation of GRB 250107D (short/hard)
- IPN triangulation of GRB 250107C
- EP250108a: Liverpool Telescope likely optical counterpart
- GRB 250108B: Gemini-North likely redshift z = 2.197
- GRB 250108B: Swift-BAT refined analysis
- GRB 250108B: 1.3m DFOT upper limit
- GRB 250108B: REM optical/NIR upper limits
- GRB 250109A /EP250109a: Fermi GBM Final Localization
- EP250109a: SVOM/VT optical candidate
- EP250109a: Global MASTER-Net observations report
- GRB 250107C: SVOM/GRM observation
- GRB 250101A: Terskol K-800 optical observations
- EP250109a: GOTO optical upper limits
- EP250109a: Swift/XRT non-detection
- GRB 250108A: Swift/UVOT Upper Limits
- EP250108a: Global MASTER-Net observations report