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"32537 results found.
- Konus-Wind detection of GRB 250119B
- IPN triangulation of GRB 250119B
- Improved IPN triangulation of GRB 250107C
- GRB 250114A: Swift-BAT refined analysis
- GRB 250121A: INTEGRAL/SPI-ACS detection
- GRB 250121A: Fermi-LAT detection
- GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
- GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
- Fermi-LAT Gamma-ray Observations of IceCube-241224A
- GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
- GRB 250119B: Fermi GBM Observation
- EP250108a/AT2025kg: 1.3m DFOT Optical observations
- Konus-Wind detection of GRB 250117A
- IPN triangulation of GRB 250117A (short)
- ATCA detection of possible radio counterpart to GRB 250114A
- EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
- GRB 250119B: INTEGRAL/SPI-ACS detection
- LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
- EP 250108A: Late-time optical observation by LCO
- GRB 250117A: SVOM/GRM observation of a short burst
- LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
- GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
- EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
- LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
- EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
- EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
- GRB 250117A: GECAM observation of a short burst
- LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
- LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250118t: Updated Sky localization
- LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
- EP250108a / AT2025kg: GMG Optical Observations
- LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
- EP250108a / AT2025kg: VLA radio upper limit
- Konus-Wind detection of GRB 250116A
- GRB 250116A: GECAM-B detection of a long burst
- GRB 241217A / EP241217B: radio detection with the VLA
- GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
- GRB 250116A: Fermi-LAT detection
- GRB 250114B: Swift-XRT afterglow detection
- GRB 250114B: SVOM/VT upper limit
- EP250108a: MeerKAT radio upper limit
- 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 250114A: LCO optical counterpart detection.
- GRB 250114B: OHP/T193 optical upper limit
- GRB 250114A: GRANDMA/TAROT optical afterglow detection
- 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
- EP250108a: correction to GCN 38908
- 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
- GRB 250114A: LCO optical observations
- GRB 250114A: TRT optical observations
- Swift GRB 250114A: Global MASTER-Net observations report
- GRB 250101A: Terskol Zeiss-2000 optical observations
- EP250108a / AT 2025kg: SAO RAS optical observations
- EP241021a: SMA radio observation
- GRB 250107A: VZLUSAT-2 detection
- GRB 250109A / EP250109a: GRBAlpha detection
- GRB 250107D: GRBAlpha detection
- 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
- 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
- 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