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"2410 results found.
- EP250812a: SVOM/VT optical counterpart
- GRB 250812A: EP-FXT counterpart detection
- GRB 250812A: Swift ToO observations
- GRB 250812A: Kilonova-Catcher optical afterglow detection
- GRB 250812A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 250812A: SVOM/VT optical afterglow confirmation
- GRB 250812A: TRT likely optical counterpart detection
- GRB 250812A: SVOM detection of a faint long burst
- GRB 250807B: SVOM/VT optical observation
- GRB 250808A: VLT X-shooter candidate counterpart
- GRB 250808A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 250808A: Fermi GBM Observation
- GRB 250808A: Swift-XRT candidate counterpart detection
- GRB 250807A: SVOM/VT optical continued observation
- GRB 250808A: SVOM detection of a long burst
- Konus-Wind detection of GRB 250807A
- GRB 250806A: SVOM/MXT refined analysis
- GRB 250806A: SVOM/ECLAIRs refined analysis
- GRB 250806A: Mondy optical observations, and nearby bright galaxy photometry
- GRB 250804B: Insight-HXMT detection
- GRB 250807A: SVOM/GRM observation
- GRB 250806A: NOT z-band upper limit and host galaxy candidate
- GRB 250807A: SVOM/VT optical observation
- GRB 250805A: Kilonova-Catcher optical upper limits
- EP250806a:SVOM/VT refined analysis
- GRB 250806A: Swift/UVOT U-band detection
- EP250806a: Liverpool telescope optical upper limit
- GRB 250806A: EP-FXT observation
- EP250806a: SVOM /VT optical candidate
- GRB 250806A: J-band upper limit from WINTER
- GRB 250806A: KAIT optical upper limit
- GRB 250806A: SVOM/VT refined analysis
- GRB 250806A: Swift-XRT counterpart detection
- GRB 250806A: Kilonova-Catcher optical upper limits
- GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 250806A: SVOM/VT optical upper limit
- GRB 250806A: SVOM detection of a soft burst
- GRB 250805A: SVOM/VT optical counterpart
- GRB 250804B: SVOM/GRM observation of a short burst
- EP250730a: SVOM/VT optical upper limit
- GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
- GRB 250725A: AstroSat CZTI detection
- GRB 250727A: EP-FXT follow-up observation
- GRB 250727A: SVOM/ECLAIRs refined analysis
- GRB 250727A: AST3-2 Upper limit
- GRB 250727A: EP-FXT counterpart detection
- GRB250727A: SVOM/VT optical upper limit
- GRB 250727A: Swift-XRT observations
- GRB 250727A: SVOM detection of a burst
- Konus-Wind detection of GRB 250725A
- GRB 250725A: SVOM/GRM observation
- GRB 250725A: Fermi-LAT detection
- GRB 250725A: SVOM/VT optical candidate
- SVOM J195836+32283 is not a real source
- SVOM J195836+32283/sb25072103: Second VT observation
- SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
- SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
- SVOM J195836+32283/sb25072103: NIR observations with WINTER
- GRB 250713A : SVOM/ECLAIRs refined analysis
- GRB 250717B: SVOM/GRM observation
- The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
- EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
- GRB 270713A: Kitab and AbAO Optical Observations
- GRB 250714A: SVOM/GRM observation
- GRB 250713A: Mephisto optical upper limits
- GRB 250713A: SVOM/VT optical upper limit
- GRB 250713A: NOT optical upper limits
- GRB 250713A: SVOM/C-GFT upper limit
- GRB 250713A: Swift-XRT observations
- GRB 250713A: EP-FXT counterpart detection
- GRB 250713A: JinShan optical upper limits
- GRB 250713A: SVOM detection of a long burst
- GRB 250711A: DDOTI Optical Upper Limit
- GRB 250711A: SVOM/GRM observation
- GRB 250704A: GRANDMA observations
- GRB 250704A: SVOM/ECLAIRs refined analysis
- IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
- GRB 250706B/C: Insight-HXMT detection
- IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
- EP250704a/GRB250704B : HCT optical and NIR upper limits
- GRB 250706B/C: Konus-Wind analysis of the prompt emission
- GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
- GRB 250704B: CALET Gamma-Ray Burst Monitor detection
- GRB 250704B / EP250704a: Mondy and AbAO optical observations
- GRB 250706B/C: VLT/X-shooter redshift z = 0.942
- GRB 250706B/C: Fermi-LAT detection
- GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 250706B: Swift/UVOT Detection
- GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
- GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
- GRB 250706B: refined SVOM/MXT data analysis
- GRB 250706B: REM optical observations
- GRB 250706A: SVOM/C-GFT upper limit in eary phase
- GRB250706B: Swift-XRT counterpart detection
- EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
- GRB 250706B: SVOM/VT optical observation
- GRB 250706B: TRT bright optical counterpart detection
- GRB 250706B: SVOM detection of a long burst
- EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
- GRB 250704B: Swift/UVOT Upper Limits