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"
24640 results found.
- LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume
- EP241126a: Optical Upper limits with Kinder observations
- IPN triangulation of GRB 241114B
- EP trigger ID 01709122294: 1.6m Mephisto multi-band optical observations
- EP241126a: GSP detects optical counterpart
- EP241126a: TRT optical counterpart detection
- LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
- EP241126a: EP detection of a fast X-ray transient
- LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
- LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
- LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
- LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
- GECAM detection of a short burst from SGR 1830
- LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
- LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
- LIGO/Virgo/KAGRA S241125n: HCT upper limit
- LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations
- GRB 241026A: radio detection with the VLA
- EP241125a: Optical upper limit with Kinder observations
- EP241125a: EP detection of an X-ray transient
- LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
- LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
- LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
- LIGO/Virgo/KAGRA S241125n: Updated Sky localization
- LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
- LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
- LIGO/Virgo/KAGRA S241109bn: Upper limits from a two-week IceCube neutrino search
- LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
- LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
- LIGO/Virgo/KAGRA S241125n: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S241122a: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S241122a: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 241117A
- GRB 241026A: VIRT Optical Upper Limit
- GRB 241025A: VIRT Optical Upper Limit
- GRB241120A: OHP/T193 optical observations
- EP241021a and EP241026b: Keck/LRIS spectroscopic observations
- GRB 241120A: Mondy and AbAO optical observations
- EP241119a: Optical upper limits with Kinder observations
- EP trigger ID 01709122294: the X-ray transient is likely a stellar flare event
- EP241119a: GIT optical upper limits
- EP241119a : J-band observations with WINTER
- GRB 241120A: Fermi GBM Observation
- EP241119a: EP detection of a fast X-ray transient
- GRB241120A: a long GRB detected by INTEGRAL
- GRB 241112B: Mephisto further optical observations
- GRB 241030A: J-band observations
- GRB 241115a: PRIME near-infrared upper limits
- GRB 241117A: Swift/BAT-GUANO localization skymap of a burst
- LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
- GRB 241115B: Fermi GBM Observation
- LIGO/Virgo/KAGRA S241114y: Updated Sky localization
- Updates to IceCube realtime alert system for muon tracks
- GRB 241117A: SVOM/GRM observation of a short burst with extended emission
- GRB 241117A: Fermi GBM Detection
- IceCube-Cascade 241116A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S241116cq: Updated Sky localization
- GRB 241115B: Swift/BAT-GUANO localization skymap of a long burst
- GRB 241115C: Fermi GBM Observation
- GRB 241115A: Swift-XRT afterglow detection
- LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
- EP241115a/GRB 241115D: Optical upper limits with Kinder observations
- GRB 241115A: Mephisto upper limits
- GRB 241113B: Mephisto upper limits
- EP241115a/GRB 241115D: Swift/XRT follow-up observation
- GRB 241115D / EP 241115a: SVOM/GRM observation
- EP241113a: Swift XRT weak detection
- GRB 241115A: Fermi GBM Observation
- GRB 241115A: LCOGT Optical Upper Limits
- GRB 241115C: Swift/BAT-GUANO localization skymap of a burst
- LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S241113p: Updated Sky localization
- EP241115a: EP detection of a fast X-ray transient
- Swift GRB 241115A: Global MASTER-Net observations report
- Fermi GRB 241115A: Global MASTER-Net observations report
- GRB 241115A: Swift detection of a burst
- EP 241113a: LBT possible optical counterpart
- LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
- GRB 241113A: Swift-BAT refined analysis
- LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
- GRB 241113A: PRIME near-infrared upper limits
- EP241113a: Global MASTER-Net observations report
- GRB 241113B: J-band upper limit from WINTER
- GRB 241113A: J-band observations with WINTER
- EP241113a : J-band observations with WINTER
- GRB 241030A: LCO optical observation
- GRB 241113B: Swift-XRT observations
- IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
- GRB 241113A: 1.6m Mephisto and 50cm array optical upper limits
- EP241113b/GRB 241113B: EP detection of GRB 241113B
- Fermi-LAT gamma-ray observations of IceCube-241113A
- LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
- GRB 241113A: Swift-XRT refined Analysis
- GRB 241113A: Swift/UVOT Detection
- GRB 241113A: REM detection of the optical/NIR afterglow
- LIGO/Virgo/KAGRA S241113p: Identification of a GW compact binary merger candidate
- GRB 241113A: LCO optical observations
- GRB 241112B: GMG Optical Upper Limit