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"
752 results found.
- GRB 250421A: AstroSat CZTI detection
- IPN triangulation of GRB 250406B (short/hard)
- Konus-Wind detection of GRB 250404A / EP250404a
- LIGO/Virgo/KAGRA S250331o: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250328ae: Identification of a GW compact binary merger candidate
- GRB 250327B: Las Cumbres optical counterpart detection
- IPN triangulation of GRB 250322B
- LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250319bu: Identification of a GW compact binary merger candidate
- GRB 250312B: Fermi GBM Observation
- GRB 250312B: Fermi GBM Final Localization
- IPN triangulation of GRB 250308A (short)
- IPN triangulation of GRB 250309B
- LIGO/Virgo/KAGRA S250226dl: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 250217C (short)
- LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250208ad: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250207bg: Identification of a GW compact binary merger candidate
- GRB 250205A: Fermi GBM Observation
- LIGO/Virgo/KAGRA S250205ee: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 250201A
- LIGO/Virgo/KAGRA S250205bk: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250204ax: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250202cu: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 250118B
- IPN triangulation of GRB 250119B
- Improved IPN triangulation of GRB 250107C
- EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
- LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 250113A
- LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 250107D (short/hard)
- LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 241128B
- LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
- GRB 241127A: Swift detection of a burst with an optical counterpart
- LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241125n: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 241117A
- LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
- Fermi trigger No 753166198: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 241107A (short/hard)
- S241102cy: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
- GRB 241030A: Swift-BAT refined analysis
- IPN triangulation of GRB 241022A (short/hard)
- IPN triangulation of GRB 241021A (long)
- GRB 241010A: Swift detection of a burst with an optical counterpart
- LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 240930B / EP 240930a
- LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 240926A
- LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 240918B
- LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240920bz: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240919bn: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 240913C / EP 240913a
- LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 240810A (short)
- GRB 240807B: AstroSat CZTI detection of a short burst
- Improved IPN triangulation of GRB 240802A / EP 240802a
- GRB 240805A: Swift/UVOT Upper Limits
- IPN triangulation of GRB 240715A (short)
- GRB 240712A: Swift detection of a burst
- IPN triangulation of GRB 240627A
- IPN triangulation of GRB 240619C
- IPN triangulation of GRB 240615A (short)
- GRB 240615A: Fermi GBM Observation
- IPN triangulation of GRB 240607A
- IPN triangulation of GRB 240603A
- IPN triangulation of the initial episode of GRB 240529A
- IPN triangulation of GRB 240504A
- IPN triangulation of GRB 240501B and GRB 240501A - possible episodes of ultra long GRB
- LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration