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"7445 results found.
- GRB 231117A: Pan-STARRS1 follow-up confirms rapid fading
- LIGO/Virgo/KAGRA S231119u: Identification of a GW compact binary merger candidate
- GRB 231117A: AKO Follow-Up Observation
- GRB 231118A: LCOGT Optical Observations
- GRB 231117A: Kinder observations with Lulin observatory for AT 2023yba without fading in r band
- GRB 231117A: Lowell Discovery Telescope Observations
- GRB 231117A: ePESSTO+ host galaxy redshift confirmation
- LIGO/Virgo/KAGRA S231118an: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231118ab: Identification of a GW compact binary merger candidate
- GRB 231117A: Keck spectroscopy of afterglow candidate
- LIGO/Virgo/KAGRA S231118d: Identification of a GW compact binary merger candidate
- GRB 231117A: GIT optical follow-up
- GRB 231117A: Keck observations indicate presence of optical afterglow in z~0.3-0.5 galaxy
- GRB 231117A: AKO Optical Upper Limit
- GRB 231117A: afterglow candidate detection from Kinder observations with Lulin observatory
- GRB 231115A : OHP/T120 optical upper limit
- GRB 231115A: optical observations from INAF observatories
- GRB 231117A: Swift detection of a bright short burst
- MAGIC observation of GRB 231115A, a possible magnetar giant flare
- GRB231115A: Liverpool Telescope imaging
- GRB 231115A / AT2023xvj: Updated GIT analysis
- GRB 231115A: archival Chandra X-ray observations
- GRB231115A: GRANDMA Observations
- GRB 231115A: Non-detection in low-latency of gravitational waves with LIGO/Virgo/KAGRA
- GRB 231115A: pre-burst ZTF upper limits for GRB optical counterpart candidate
- GRB 231106A: TESS identification of candidate optical counterpart
- GRB 231115A: archival HST observations
- GRB 231115A: Swift ToO observations
- GRB 231115A: significance of INTEGRAL localization alignment with M82
- GRB 231115A: a short hard GRB detected by IBAS, poistionally coincident with M82
- LIGO/Virgo/KAGRA S231113bw: Updated Sky localization, EM Bright Classification, and Source Classification
- LIGO/Virgo/KAGRA S231114n: Updated Sky localization
- LIGO/Virgo/KAGRA S231113bw: GROWTH-India coverage and upper limits
- LIGO/Virgo/KAGRA S231114n: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231113bw: Upper limits from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S231113cd: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S231113bb: Updated Sky localization
- LIGO/Virgo/KAGRA S231113bw: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S231113bw: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231113bb: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231112ag: Retraction of GW compact binary merger candidate
- GRB 231111A: Swift detection of a burst with an optical counterpart
- LIGO/Virgo/KAGRA S231110g: Updated Sky localization
- LIGO/Virgo/KAGRA S231110g: Identification of a GW compact binary merger candidate
- IceCube-231103A: No candidates from the Zwicky Transient Facility
- LIGO/Virgo/KAGRA S231108u: Updated Sky localization
- LIGO/Virgo/KAGRA S231108u: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231102w: Upper limits from Swift/BAT-GUANO
- GRB 231104A: 3.6m DOT optical upper limit
- LIGO/Virgo/KAGRA S231106y: one counterpart neutrino candidate from IceCube neutrino searches
- LIGO/Virgo/KAGRA S231104ac: Updated Sky localization
- GRB 231104A: AKO Upper Limit
- LIGO/Virgo/KAGRA S231104ac: Identification of a GW compact binary merger candidate
- GRB231104A: LCOGT Optical Upper Limits
- GRB 231104A: Swift detection of a bright burst
- IceCube-231103A - IceCube observation of a high-energy neutrino candidate track-like event
- LIGO/Virgo/KAGRA S231102w: Updated Sky localization
- GRB 231024A: GRANDMA observations of AT2023vuc/GOTO23baj candidate
- LIGO/Virgo/KAGRA S231102w: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231029y: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231030av: Retraction of GW compact binary merger candidate
- GRB 231024A: AKO Optical Counterpart Candidate
- LIGO/Virgo/KAGRA S231029y: One counterpart neutrino candidate from IceCube neutrino searches
- LIGO/Virgo/KAGRA S231029y: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231028bg: Updated Sky localization
- LIGO/Virgo/KAGRA S231028bg: Identification of a GW compact binary merger candidate
- IceCube-231027A - IceCube observation of a high-energy neutrino candidate track-like event
- IC231004A: GRANDMA observations of AT2023uqf/ZTF23abidzvf candidate
- GRB 231024A: Fermi GBM Observation
- GRB 231024A: X-shooter spectroscopy of AT2023vuc/GOTO23baj reveals a young supernova with flash ionisation features
- GRB 231024A: LCOGT and ZTF detections of the GOTO optical counterpart candidate
- GRB 231024A: GOTO optical counterpart candidate
- LIGO/Virgo/KAGRA S231025a: two counterpart neutrino candidates from IceCube neutrino searches
- The photometry of the transient in Messier 31 field: GMG observation
- LIGO/Virgo/KAGRA S231020bw: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S231021az: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S231020bw: Updated Sky localization
- GRB 231017A: Mondy optical observations. A possible candidate for an afterglow or host galaxy.
- LIGO/Virgo/KAGRA S231020ba: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S231020ba: Upper limits from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S231020bw: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231020ba: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S231020ba: Identification of a GW compact binary merger candidate
- IceCube-231004A: Upper limits from Fermi-GBM Observations
- GRB 231017A: Swift/UVOT Upper Limit
- GRB 231017A: GOTO optical upper limits
- GRB 231017A: JinShan optical upper limit
- GRB 231018A: GROWTH-India Follow-Up of a Fermi Long GRB
- LIGO/Virgo/KAGRA S231018cb: One counterpart neutrino candidate event from an IceCube neutrino search
- GRB 231017A: LCOGT Optical Upper Limits
- GRB 231017A: Swift ToO observations
- GRB 231017A: Swift/BAT-GUANO candidate arcminute localization of a burst
- LIGO/Virgo/KAGRA S231014r: Upper limits from Swift/BAT-GUANO
- (correction) Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field
- Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field.
- IceCube-231014A - IceCube observation of a high-energy neutrino candidate track-like event
- LIGO/Virgo/KAGRA S231014r: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231001aq: Updated Sky localization
- IceCube-231004A: One Candidate Counterpart from the Zwicky Transient Facility
- LIGO/Virgo/KAGRA S231005j: Upper limits from Swift/BAT-GUANO