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"2411 results found.
- GRB 251007A: NOT optical observations
- GRB 251006B: Insight-HXMT detection
- GRB 251007A: SVOM/C-GFT optical observations
- GRB 251005C: PRIME J-band upper limit
- GRB 251007B: SVOM/C-GFT upper limit
- GRB 251007B: SVOM detection of a faint burst
- GRB 251006B/EP251006a: SVOM/VT optical candidate
- GRB 251006B: SVOM/GRM observation
- GRB 251005C: SVOM/VT optical fading
- GRB 251005C: SVOM/GRM observation of a likely short GRB
- GRB 251005C: VLT/X-shooter Imaging
- GRB 251002A: LAST optical observations
- GRB 251005C: SVOM/VT optical candidate
- GRB 250902A: MSU cubesats detection
- GRB 251002A: Mondy/AZT-33IK optical observations
- GRB 251002A: Insight-HXMT detection
- GRB 251002A: Insight-HXMT detection
- Fermi GBM Sub-Threshold Detection of GRB 250910A
- GRB 251002A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
- GRB 251002A: Swift/UVOT detection
- GRB 251002A: Fermi GBM Observation
- GRB 251001C: SVOM/GRM observation
- GRB 251002A: AKO Early Optical Afterglow Detection
- GRB 251002A: Swift-XRT afterglow detection
- GRB 251002A: Kilonova-Catcher optical afterglow detection
- GRB 251002A: AbAO optical observations
- GRB 251002A: SVOM/COLIBRÍ (FM-GFT) optical observations
- GRB 251002A: J band observations by SYSU 80cm infrared telescope
- GRB 251002A: OHP/T193 MISTRAL optical afterglow detection
- GRB 251002A: VLT/X-shooter spectroscopic redshift z = 2.178
- GRB 251002A: EP-FXT counterpart detection
- Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
- GRB 251002A: BOOTES-6 early optical detection
- GRB 251002A: ULL-ASTRO-MASTER early detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
- GRB 251002A: LCO optical observation
- GRB 251002A: SVOM/VT optical observation
- GRB 251002A: SVOM detection of a burst
- GRB 251001A: SVOM/GRM observation
- GRB 251001B: SVOM/VT optical observation
- GRB 250930A: SVOM/GRM observation
- GRB 250910A / EP250910a: VLT/X-shooter host galaxy redshift z = 0.592
- GRB 250916A: SVOM/VT optical observation
- GRB 250924A: SVOM/GRM observation
- GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
- GRB 250925A: SVOM/GWAC-F60A upper limit
- GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations
- GRB 250922A: SVOM/GRM observation
- GRB 250924A: SVOM/VT optical observation
- GRB 250920C: Kilonova-Catcher optical afterglow detection
- GRB 250922B: SVOM/GRM observation
- GRB 250919A / EP250919a: further LCO optical observation
- Konus-Wind detection of GRB 250920C
- GRB 250920C: KAIT optical observations
- GRB 250920C: COLIBRÍ optical observations
- GRB 250920C: NIR observations with WINTER
- Konus-Wind detection of GRB 250920A
- IPN triangulation of GRB 250920A (long/bright)
- GRB 250920C: SVOM/GRM observation
- GRB 250920A: NuSTAR detection of bright prompt emission
- GRB 250920B: Fermi GBM Observation
- GRB 250920A: Fermi GBM Detection
- GRB 250920A: SVOM/GRM observation
- GRB 250920B: SVOM/C-GFT optical observations
- GRB 250919A / EP250919a: LCO optical observation
- Konus-Wind detection of GRB 250919A
- GRB 250919A / EP250919a: Insight-HXMT detection
- GRB 250919A/EP250919a: SVOM/VT optical observation
- GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
- GRB 250919A: Glowbug gamma-ray detection
- GRB 250919A: Fermi GBM Observation
- GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
- GRB 250918A: SVOM/GRM observation
- 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
- GRB 250912A: SVOM/ECLAIRs refined analysis
- GRB 250910A: SVOM/ECLAIRs refined analysis
- SVOM/sb25091517: Confirmation of a stellar flare by SVOM/VT
- SVOM/sb25091517: FRAM-ORM stellar flare - transient observation
- 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 250912A: Swift-XRT observations
- GRB250912A: VLT/HAWK-I follow-up observations
- GRB 250912A: VLT observations
- GRB 250912A: Fermi GBM Observation
- 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
- GRB 250912A: SVOM detection of a burst
- GRB 250910B: SVOM/GRM observation
- EP250911a: SVOM/VT optical observation
- GRB 250910A / EP250910a: Swift-XRT afterglow detection
- 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
- GRB 250903A: SVOM/ECLAIRs refined analysis
- GRB 250910A: SVOM/VT optical upper limit
- GRB 250910A: LCO optical upper limit