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"7444 results found.
- GRB240204A: Swift/UVOT Upper Limits
- GRB 240205B: ATCA detection of radio counterpart
- GRB 240204A: Mondy optical afterglow candidate
- IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 240128A: Tiled Swift observations
- GRB 240122A: ATCA detection of radio counterpart
- GRB240122A: PRIME near infrared detection
- GRB 240123A : MITSuME Akeno optical afterglow candidate detection
- GRB 240122A: Swift/UVOT Upper Limits
- IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 240123A: Swift detection of a burst with a possible optical counterpart
- GRB 240122A: VLT/X-shooter redshift confirmation
- GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
- GRB 240122A: GOTO optical counterpart candidate
- GRB 240122A: Tiled Swift observations
- IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
- GRB 240118A: Swift ToO observations
- GRB 240118A: AbAO optical upper limit
- LIGO/Virgo/KAGRA S240109a: Upper limits from Swift/BAT-GUANO
- IceCube-240105A: ZTF optical observation of blazar PKS 0446+11
- GRB 240112C: Swift detection of a burst with an optical counterpart
- LIGO/Virgo/KAGRA S240109a: Updated Sky localization
- LIGO/Virgo/KAGRA S240109a: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240104bl: Upper limits from Swift/BAT-GUANO
- Update of IceCube-240105A - Corrected errors
- LIGO/Virgo/KAGRA S240107b: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S240107b: Identification of a GW compact binary merger candidate
- GRB 240101A: 1.3m DFOT optical observations
- IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
- LIGO/Virgo/KAGRA S240104bl: Updated Sky localization
- LIGO/Virgo/KAGRA S240104bl: Identification of a GW compact binary merger candidate
- GRB 231220A: Swift-UVOT upper limit
- GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
- GRB 240101B: KAIT Optical Upper Limit
- GRB 240101A: KAIT Optical Upper Limit
- GRB 240101B: Swift detection of a burst
- LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
- GRB 231230A: Swift detection of a burst
- LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231226av: Updated Sky localization
- LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231223j: Updated Sky localization
- LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
- GRB 231222A: Tiled Swift observations
- GRB 231220A: Swift-XRT follow-up observations
- GRB 231220A: Swift ToO observations
- GRB 231216A: GAD Observatory, La Spezia, Italy upper limit
- GRB 231216A: optical upper limits from the INAF Asiago Observatory
- GRB 231215A: AMI-LA radio detection
- GRB 231216A: Swift detection of a burst
- GRB 231215A: GAD Observatory, La Spezia, Italy upper limit;
- GRB 231215A : OHP/T193 optical afterglow detection
- LIGO/Virgo/KAGRA S231215i: 3 counterpart neutrino candidate events from an IceCube neutrino search
- GRB 231215A : MITSuME Akeno optical afterglow candidate detection
- GRB 231214A: Swift detection of a burst
- LIGO/Virgo/KAGRA S231213ap: Updated Sky localization
- LIGO/Virgo/KAGRA S231213ap: Identification of a GW compact binary merger candidate
- IceCube-231211A - IceCube observation of a high-energy neutrino candidate track-like event
- LIGO/Virgo/KAGRA S231206cc: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231206ca: Upper limits from Swift/BAT-GUANO
- IceCube-231202A: No candidates from the Zwicky Transient Facility
- LIGO/Virgo/KAGRA S231206ca: Updated Sky localization
- LIGO/Virgo/KAGRA S231206cc: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S231206cc: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231206ca: Identification of a GW compact binary merger candidate
- GRB231115A: TURBO Pre-Burst Optical Upper Limits
- LIGO/Virgo/KAGRA S231205c: One counterpart neutrino candidate event from an IceCube neutrino search
- GRB 231205B: Swift detection of a burst
- LIGO/Virgo/KAGRA S231129ac: Upper limits from Swift/BAT-GUANO
- IceCube-231202A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 231129C: PROMPT optical upper limits for the MAXI/GSC X-ray counterpart and the MASTER afterglow candidate
- Optical transient in the field of Messier 31, likely a new blazar: back to bright state
- GRB 231129C: Tiled Swift observations
- LIGO/Virgo/KAGRA S231129ac: Updated Sky localization
- GRB 231129B: Tiled Swift observations
- LIGO/Virgo/KAGRA S231129ac: Identification of a GW compact binary merger candidate
- GRB 231129A: Swift detection of a burst
- LIGO/Virgo/KAGRA S231127cg: Updated Sky localization
- LIGO/Virgo/KAGRA S231127cg: Identification of a GW compact binary merger candidate
- GRB 231117A: MeerKAT 1.3GHz detection
- IceCube-231125A - IceCube observation of a high-energy neutrino candidate track-like event
- LIGO/Virgo/KAGRA S231118an: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S231123cg: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231118d: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231118an: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231114n: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231113bb: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231119u: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S231118ab: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S231118d: Updated Sky localization and Source Classification
- GRB 231117A: AMI-LA radio observations
- GRB 231117A: LDT Confirmation of Optical Fading
- GRB 231117A : MITSuME Akeno optical afterglow candidate detection
- LIGO/Virgo/KAGRA S231119ab: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S231119u: One counterpart neutrino candidate from IceCube neutrino searches
- GRB 231117A: OHP/T120 optical observations
- GRB 231117A: Pan-STARRS1 follow-up confirms rapid fading