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"32490 results found.
- GRB 250920B: Swift-BAT refined analysis
- GRB 250916A: FTW optical and NIR observations of the counterpart
- GRB 250920C: Swift/UVOT Detection
- GRB 250920B: Fermi GBM Observation
- GRB 250920A: Fermi GBM Detection
- GRB 250920C: Fermi GBM Observation
- Swift GRB 250920C: Global MASTER-Net observations report
- GRB 250920B: Swift/UVOT Detection
- GRB 250920B: FTW optical and NIR observations of the counterpart
- GRB 250920C: Optical counterpart detection by LCO
- GRB 250920A: SVOM/GRM observation
- GRB250920C: LCOGT Optical Detection
- GRB 250920B: SVOM/C-GFT optical observations
- GRB 250920C: GOTO optical counterpart candidate
- GRB 250919A / EP250919a: LCO optical observation
- Konus-Wind detection of GRB 250919A
- Swift GRB 250920B: Global MASTER-Net observations report
- GRB 250919A / EP250919a: Insight-HXMT detection
- GRB 250920A: AstroSat CZTI detection
- GRB 250919A/EP250919a: SVOM/VT optical observation
- GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
- GRB 250916A: Mondy R-band optical observations
- GRB 250919A: Glowbug gamma-ray detection
- GRB 250919A: Fermi GBM Observation
- Fermi GRB 250918A: Global MASTER-Net observations report
- GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
- GRB 250918A: SVOM/GRM observation
- GRB 250919A/EP250919A: Swift/UVOT afterglow detection
- GRB 250919A: Swift-XRT afterglow detection
- GRB 250919A: Fermi-LAT detection
- EP250919a/GRB 250919A: Gemini/GMOS-S spectroscopic redshift z = 1.145
- GRB 250919A: SVOM/GRM observation of a very bright GRB
- EP250919a: Global MASTER-Net observations report
- EP250919a: Einstein Probe detection of an X-ray transient
- Correction for GCN 41877: EP-WXT ID is 01709243841
- GRB 250916A: Fermi GBM Observation
- Fermi GRB 250919A: Global MASTER-Net observations report
- GRB 250916A: KAIT optical observations
- GRB 250917B: VLT/HAWK-I near-infrared observations
- GRB 250916A: NuSTAR detection of the prompt emission
- GRB 250916A: further SAO RAS optical observations
- GRB 250912A: SVOM/ECLAIRs refined analysis
- GRB 250917B: Swift-BAT refined analysis
- GRB 250917B: Swift/UVOT Upper Limits
- GRB 250916A: OSIRIS+/GTC redshift z = 2.015
- GRB 250916A: Swift-XRT observations
- EP250916a: EP-FXT follow-up observation
- GRB 250916A: MAO/AZT-22 optical observations
- GRB 250916A: SAO RAS optical observations
- GRB 250916A : GIT optical observations
- LIGO/Virgo/KAGRA S250917aq: Updated Sky localization
- GRB 250916A: Glowbug gamma-ray detection
- GRB250917B: WFST optical observations
- GRB 250916A: Swift ToO observations
- GRB 250917B: Fermi GBM Observation
- LIGO/Virgo/KAGRA S250917aq: Identification of a GW compact binary merger candidate
- Fermi GRB 250917B: Global MASTER-Net observations report
- GRB 250916A: GOTO optical counterpart candidate
- GRB 250916A: AstroSat CZTI detection of a bright long burst
- GRB 250910A: SVOM/ECLAIRs refined analysis
- Fermi GRB 250916A: Global MASTER-Net observations report
- EP250827b: VLA Observations
- LIGO/Virgo/KAGRA S250818k: HCT optical follow-up
- SVOM/sb25091517: Confirmation of a stellar flare by SVOM/VT
- SVOM/sb25091517: FRAM-ORM stellar flare - transient observation
- GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
- GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 250912A: Swift-XRT observations
- GRB250912A: VLT/HAWK-I follow-up observations
- GRB 250912A: VLT observations
- GRB 250912A: Fermi GBM Observation
- GRB 250911A: Insight-HXMT detection
- GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
- GRB 250912A:SVOM/VT optical upper limit
- GRB 250912A: LCO optical upper limit
- Fermi GRB 250912A: Global MASTER-Net observations report
- EP250911a: Global MASTER-Net observations report
- GRB 250912A: SVOM detection of a burst
- EP250908c: tentative VLT/FORS2 redshift z = 2.87
- EP250911a: Upper limit from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S250912f: Updated Sky localization
- GRB 250911A: GECAM-B detection
- GRB 250911A: Swift-BAT refined analysis
- EP250911a: GTC/OSIRIS+ spectroscopic redshift z = 3.84
- LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
- EP250911a: refined analysis of the EP-WXT and EP-FXT observations
- GRB 250910B: SVOM/GRM observation
- EP250911a: SVOM/VT optical observation
- GRB 250911A: MASTER optical counterpart observations
- EP250911a: SAO RAS optical observations
- EP250911a: Swift-XRT observations
- EP250911a: Optical detection with Kinder observations
- GRB 250911A: Swift/UVOT Detection
- GRB 250910A / EP250910a: Swift-XRT afterglow detection
- GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
- GRB 250909B: Insight-HXMT detection
- GRB 250909B: SVOM/GRM observation
- LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
- GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
- EP250911a: COLIBRÍ optical observations