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.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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"19171 results found.
- GRB 251013C: Fermi GBM Observation
- GRB 251013D: Swift ToO observations
- GRB 251014A: DDOTI Upper Limit
- GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
- GRB 251014A: SAO RAS optical upper limit
- GRB 251014A: Fermi GBM Observation
- GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
- GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
- Swift GRB 251014A: Global MASTER-Net observations report
- GRB 251014A: Swift detection of a possibly-short burst
- GRB 251013C: Swift-XRT counterpart detection
- GRB 251003A: Mondy optical upper limit
- GRB 251011B inspection: MASTER orphan GRB detection
- GRB 251011B: Swift/UVOT Upper Limits
- GRB 251011B: SVOM/GRM observation
- GRB 251011B: Swift-XRT refined Analysis
- GRB 251011B: Fermi GBM Observation
- GRB 251011B : MASTER optical observations
- GRB 251011B: Enhanced Swift-XRT position
- GRB 251011B: Swift detection of a burst
- GRB 251007B: Swift/UVOT Upper Limits
- GRB251007A: Swift/UVOT Detection
- GRB 251007A: Swift-BAT refined analysis
- GRB 251007A: SVOM/GRM observation
- GRB 251007A: Insight-HXMT detection
- GRB 251006A: CALET Gamma-Ray Burst Monitor detection
- GRB 251006A: Fermi GBM Observation
- GRB 251007A: 1.5m OSN and 2.2m CAHA optical follow-up
- GRB 251003A: Fermi GBM Observation
- GRB 251007B: COLIBRÍ optical upper limit
- GRB 251007A: AstroSat CZTI detection
- GRB 250917B: iTelescope T-26 upper limit
- GRB 251007A: Swift-XRT refined Analysis
- GRB 251007A: Enhanced Swift-XRT position
- GRB 251007B: Swift-XRT refined Analysis
- GRB 251007B: Enhanced Swift-XRT position
- GRB 251007A: AKO Optical Upper Limit
- GRB 251007A: CALET Gamma-Ray Burst Monitor detection
- GRB 251007A: SVOM/C-GFT optical observations
- GRB 251005C: PRIME J-band upper limit
- Swift GRB 251007B: Global MASTER-Net observations report
- GRB 251007A: Glowbug gamma-ray detection
- Swift GRB 251007A: Global MASTER-Net observations report
- GRB 251007B: SVOM detection of a faint burst
- GRB 251007B: Swift detection of a burst
- GRB 251007A: Swift detection of a burst with an optical counterpart
- GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
- GRB 251005C: SVOM/GRM observation of a likely short GRB
- GRB 251005C: COLIBRÍ optical observations
- GRB 251003A: LAST optical observations
- GRB 251005C: SVOM/VT optical candidate
- GRB 251005C: AstroSat CZTI detection
- GRB 251005C: Swift/UVOT Upper Limits
- GRB 251005C: Swift-XRT refined Analysis
- GRB 251005C: Fermi GBM Observation
- Swift GRB 251005A: Global MASTER-Net observations report
- GRB 251005C: Enhanced Swift-XRT position
- GRB 251005C: GOTO optical upper limits
- GRB 251005C: Swift detection of a burst
- GRB 251003A: Swift-BAT refined analysis
- GRB 251003A: Swift/UVOT Upper Limits
- GRB 251002A: Swift/UVOT detection
- GRB 251003A: Swift-XRT refined Analysis
- GRB 251003A: COLIBRÍ photometric redshift
- GRB 251003A: Enhanced Swift-XRT position
- GRB 251003A: GTC/OSIRIS+ spectroscopic redshift z = 4.412
- GRB 251003A: Kilonova-Catcher optical afterglow detection
- GRB 251002A: Swift-XRT afterglow detection
- GRB 251001B: AbAO optical upper limit
- GRB 251003A: LCOGT Optical Detection
- GRB 251003A: COLIBRÍ optical detection of the fading afterglow
- GRB 251003A: 1.5m OSN afterglow candidate
- GRB 251003A: Prompt enhanced Swift-XRT position
- GRB 251003A: Swift detection of a burst
- Swift GRB251003A: Global MASTER-Net observations report
- GRB 251001B: Swift-BAT refined analysis
- GRB 251001B: Swift/UVOT Detection
- GRB 251001B: GTC/OSIRIS+ spectroscopic redshift z = 2.162
- GRB 251001B: Swift-XRT refined Analysis
- GRB 251001B: SVOM/VT optical observation
- Swift GRB 251001B: Global MASTER-Net observations report
- GRB 251001B: Fermi GBM Observation
- GRB 251001B: Enhanced Swift-XRT position
- GRB 251001B: LCOGT Optical Observations
- GRB 251001B: TRT optical afterglow detection and potential host galaxy
- GRB 251001B: GOTO optical counterpart detection
- GRB 251001B: Swift detection of a burst
- GRB 250925A: MAO/AZT-22 optical observations
- GRB 250925A: Mondy I-band optical observations
- GRB 250924A: SVOM/GRM observation
- GRB 250925A: Swift-XRT refined Analysis
- GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
- GRB 250925A: Swift/UVOT Upper Limits
- GRB 250925A: Swift-BAT refined analysis
- GRB 250925A: Mondy and AbAO optical observations
- GRB 250925A: COLIBRÍ photometric redshift
- GRB 250925A : MITSuME Akeno optical upper limits
- GRB 250925A: JinShan optical observations
- GRB 250925A: 1.5m OSN optical detection and redshift with the 10.4m GTC/OSIRIS+
- GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations