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"37504 results found.
- GRB 260601A: Glowbug gamma-ray detection of a short burst
- GRB 260531B: Glowbug gamma-ray detection
- GRB 260516D: VLA radio detection
- GRB 260601A: Fermi GBM Observation
- GRB 260530C: SVOM/ECLAIRs detection of a burst through on-ground search
- GRB 260527A/EP260527a: Glowbug gamma-ray detection
- Fermi GRB 260601A: Global MASTER-Net observations report
- GRB 260601A: Fermi GBM Final Real-time Localization
- GRB 260531B: GECAM-B observation
- GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
- GRB 260531C: Fermi GBM Final Localization Correction
- Fermi Gamma-ray Burst Monitor trigger 801900520/260531256 is not a GRB
- Fermi trigger No 801900520: Global MASTER-Net observations report
- GRB 260531B: Fermi GBM Final Real-time Localization
- GRB 260531A: MAXI/GSC detection
- AT 2026nuz: COLIBRÍ optical observations
- IPN triangulation of GRB 260527A / EP260527a
- EP260527a/GRB 260527A: further FTW optical and NIR observations
- GRB 260530B: SVOM/GRM detection of a possible bright short GRB
- GRB 260530A: Fermi GBM Final Real-time Localization
- GRB 260527A / EP260527a: VLA radio detection
- EP260527a/GRB 260527A: optical upper limit with Kinder observations
- GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
- GRB 260529A: GOTO tentative optical afterglow candidate
- GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
- GRB 260527A/EP260527a: Insight-HXMT detection
- Fermi GRB 260529A: Global MASTER-Net observations report
- GRB 260529A: Fermi GBM Final Real-time Localization
- GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
- EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
- EP260527a / GRB 260527A: NOT optical observations
- GRB 260527A/EP260527a: FTW optical and NIR observations
- 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
- GRB 260526A: GECAM-B observation
- Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
- Fermi trigger No 801580882: Global MASTER-Net observations report
- GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
- GRB 260525A: AstroSat CZTI detection
- Fermi GRB 260526A: Global MASTER-Net observations report
- GRB 260526A: Fermi GBM Final Real-time Localization
- Fermi GRB 260525A: Global MASTER-Net observations report
- GRB 260525A: Fermi GBM Final Real-time Localization
- GRB 260523B: AstroSat CZTI detection
- GRB 260523B: GECAM-B observation
- Fermi GRB 260523A: Global MASTER-Net observations report
- GRB 260523B: Fermi GBM Final Real-time Localization
- GRB 260523A: Fermi GBM Final Real-time Localization
- GRB 260522A: Fermi GBM Observation
- GRB 260522B: NuSTAR detection of prompt emission
- GRB 260522B: Fermi GBM Final Real-time Localization
- GRB 260522A: GOTO optical upper limit
- Fermi trigger No 801135305: Global MASTER-Net observations report
- Fermi GRB 260522A: Global MASTER-Net observations report
- GRB 260522A: Fermi-LAT detection
- GRB 260519C: SVOM/GRM observation
- GRB 260522A: Fermi GBM Final Real-time Localization
- GRB 260511A: iTelescope T-75 optical detection
- GRB 260520B: SVOM/GRM observation
- GRB 260411B: TERI Gamma-ray detection
- GRB 260407A: TERI Gamma-ray detection
- GRB 260307A: TERI Gamma-ray detection
- GRB 260225D: TERI Gamma-ray detection
- GRB 251118A: TERI Gamma-ray detection
- GRB 251113A: TERI Gamma-ray detection
- GRB 260428A: TERI Gamma-ray detection
- Konus-Wind detection of GRB 260519C
- GRB 260520B: Fermi GBM Final Localization
- GRB 260509A: SVOM/ECLAIRs refined analysis
- GRB 260520A: Fermi GBM Final Localization
- GRB 260519D: Fermi GBM Final Localization Correction
- GRB 260519C: NuSTAR detection of prompt emission
- Konus-Wind detection of GRB 260518A
- GRB 260519B: Fermi GBM Final Localization
- GRB 260519A: Fermi GBM Final Localization
- GRB 260518A: AstroSat CZTI detection of a long burst
- GRB 260516D: SVOM/ECLAIRs refined analysis
- GRB 260515A: SVOM/ECLAIRs refined analysis
- GRB 260421B: radio detection with the VLA
- GRID detection of GRB 260511A
- GRB 260509A: CrAO ZTSh optical upper limit (Duplicate Submission)
- GRB 260509A: CrAO ZTSh optical upper limit
- GRB 260516D: EP-FXT follow-up observation
- GRB 260516D: GOTO optical counterpart detection
- GRB 260516D: LCO optical observations
- GRB 260515A: further Liverpool Telescope observations
- GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
- GRB 260516D: GROWTH-India Telescope optical detection
- GRB 260516D: SVOM/VT optical bright candidate
- GRB 260516D: FRAM-ORM optical limit
- GRB 260515A: CrAO ZTSh BVRI optical observations
- Fermi GRB 260516C: Global MASTER-Net observations report
- GRB 260516D: SVOM possible detection of a burst
- GRB 260516C: Fermi GBM Final Real-time Localization
- Konus-Wind detection of GRB 260515A
- GRB 260515A: Liverpool Telescope optical detection
- GRB 260515A: LCO optical counterpart detection