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"5816 results found.
- GRB 250922A: SVOM/GRM observation
- GRB 250924A: 1.6m Mephisto optical upper limits
- GRB 250924A: AstroSat CZTI detection
- GRB 250914A: AstroSat CZTI detection
- GRB 250920B: AstroSat CZTI detection
- GRB 250924A: SVOM/VT optical observation
- GRB 250924A: J-band detection with WINTER
- GRB 250924A: GROWTH-India Telescope Upper Limits
- GRB 250924A: Mondy optical observations, afterglow fading
- GRB 250922B: SVOM/GRM observation
- GRB 250920C: TRT optical observation
- GRB 250924A: COLIBRÍ optical observations
- Swift GRB 250924A: Global MASTER-Net observations report
- GRB 250924A: DDOTI Detection of the Optical Counterpart
- GRB 250924A: Swift detection of a burst with an optical counterpart
- GRB 250920B: AbAO optical upper limits
- GRB 250920B: CrAO ZTSH optical observations
- GRB 250920C: COLIBRÍ optical observations
- GRB 250922C: AstroSat CZTI detection of a short burst
- Fermi GRB 250922B: Global MASTER-Net observations report
- GRB 250920C: NIR observations with WINTER
- GRB 250920B: NIR observations with WINTER
- Fermi trigger No 780156732: Global MASTER-Net observations report
- IPN triangulation of GRB 250920A (long/bright)
- GRB 250920B: Glowbug gamma-ray detection
- GRB 250916A: CrAO ZTSh R-band optical observations
- GRB 250920B: Kitab-ISON optical upper limit
- GRB 250917B: Mondy and Zeiss-1000 SAO RAS optical observations, optical observations, afterglow candidate
- GRB 250920C: SVOM/GRM observation
- GRB 250920A: NuSTAR detection of bright prompt emission
- GRB 250920C: GROWTH-India Telescope optical observations
- GRB 250916A: FTW optical and NIR observations of the counterpart
- Swift GRB 250920C: Global MASTER-Net observations report
- GRB 250920B: FTW optical and NIR observations of the counterpart
- GRB 250920C: Optical counterpart detection by LCO
- GRB 250920A: SVOM/GRM observation
- GRB 250920B: SVOM/C-GFT optical observations
- GRB 250920C: GOTO optical counterpart candidate
- GRB 250920C: Swift detection of a burst
- LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
- Swift GRB 250920B: Global MASTER-Net observations report
- GRB 250919A / EP250919a: Insight-HXMT detection
- GRB 250920A: AstroSat CZTI detection
- GRB 250920B: Swift detection of a burst with a bright optical counterpart.
- GRB 250919A/EP250919a: SVOM/VT optical observation
- GRB 250916A: Mondy R-band optical observations
- GRB 250919A: Glowbug gamma-ray detection
- Fermi GRB 250918A: Global MASTER-Net observations report
- GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
- GRB 250918A: SVOM/GRM observation
- 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
- Fermi GRB 250919A: Global MASTER-Net observations report
- 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
- LIGO/Virgo/KAGRA S250918aw: 1 counterpart neutrino candidate event from an IceCube neutrino search
- GRB 250916A: OSIRIS+/GTC redshift z = 2.015
- GRB 250916A: Swift-XRT observations
- EP250916a: EP-FXT follow-up observation
- GRB 250916A : GIT optical observations
- LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
- GRB 250916A: Glowbug gamma-ray detection
- GRB250917B: WFST optical observations
- 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
- The EP-WXT trigger 01709241037 is likely a flaring star
- GRB 250916A: AstroSat CZTI detection of a bright long burst
- GRB 250910A: SVOM/ECLAIRs refined analysis
- EP250916a: Einstein Probe detection of an X-ray transient
- Fermi GRB 250916A: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250818k: HCT optical follow-up
- SVOM/sb25091517: Confirmation of a stellar flare by SVOM/VT
- SVOM/sb25091517: SVOM detection of an X-ray transient
- GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
- GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
- 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
- The EP-WXT trigger 01709240768 is likely a flaring star
- Fermi GRB 250912A: Global MASTER-Net observations report
- EP250911a: Global MASTER-Net observations report
- GRB 250912A: SVOM detection of a burst
- IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
- EP250911a: Upper limit from Fermi-GBM Observations
- GRB 250911A: GECAM-B detection
- 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
- GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
- GRB 250909B: Insight-HXMT detection
- GRB 250909B: SVOM/GRM observation
- GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery