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').
- 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
- EP250109a: EP-WXT detection of an X-ray transient
- LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
- GRB 250108A: NOT optical upper limit
- EP250108a: EP-WXT detection of an X-ray transient
- LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
- GRB 250108B: Swift-XRT refined Analysis
- Swift GRB 250108B: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
- LIGO/Virgo/KAGRA S250108ha: Retraction of GW compact binary merger candidate
- GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
- GRB 250103A: 1.6m Mephisto optical observations
- GRB 250108A: Swift-XRT afterglow detection
- GRB 250108A:SVOM/VT optical candidate
- LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
- GRB 250108B: Swift/UVOT Upper Limits
- GRB 250103A: Swift-XRT afterglow detection
- GRB 250108B: Enhanced Swift-XRT position
- GRB 250108B: Swift detection of a burst
- GRB 250108A: Swift ToO observations
- GRB 250108A: SVOM detection of a soft long burst
- GRB 250107A: Fermi GBM Observation
- GRB 241228B: Fermi-LAT detection
- Fermi GRB 250107B: Global MASTER-Net observations report
- GRB 250107A: Swift ToO observations
- GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
- GRB 250107B: Fermi GBM Final Real-time Localization
- GRB 250106A: SVOM/VT 2nd optical deep observation
- GRB 250101A: J band upper limit by SYSU 80cm telescope
- GRB 250107A: Fermi GBM Final Real-time Localization
- EPWXT01709129925: Xinglong optical observations
- GRB 250106A: NOT optical observations
- LIGO/Virgo/KAGRA S250104v: Updated Sky localization
- GRB 250103B: REM optical/NIR upper limits
- GRB 250101A: REM optical/NIR counterpart detection
- GRB 250106A: Swift-XRT observations
- GRB 250106A: SVOM/VT optical candidate
- GRB 250106A: Swift ToO observations
- The EP-WXT trigger 01709129925 is likely a flaring star