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"
24653 results found.
- Fermi-LAT Gamma-ray Observations of NuEm-240926A
- GRB 240910A: LBT optical observations
- GRB 241006A: Swift-XRT refined Analysis
- GRB 240821A: Host galaxy redshift from VLT/X-shooter
- GRB 241006A: PRIME near-infrared upper limits
- GRB 241006A: Swift/UVOT Upper Limits
- LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
- GRB 241001A: Swift-XRT afterglow detection
- GRB 241006A: Enhanced Swift-XRT position
- GRB 241006A: Swift detection of a burst
- GRB 240930B: SVOM/C-GFT optical upper limit
- LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
- GRB 241001A : ECLAIRs spectral analysis and XRF classification
- GRB 241002B: PRIME near-infrared detection in 2nd epoch
- GRB 241002B: Fermi GBM Observation
- GRB 241002B: Swift-XRT observations
- GRB 241002C: SVOM/C-GFT optical upper limit
- GRB 241002A: Swift-BAT refined analysis
- GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
- GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
- GRB 241002B: PRIME near-infrared detection
- LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
- Fermi-GBM Sub-Threshold Detection of GRB 241002D
- IPN triangulation of GRB 240930B / EP 240930a
- GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
- GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
- GRB 240929A: SAO RAS, Mondy, and CrAO optical observations
- GRB 241002C : MITSuME Akeno optical upper limits
- LIGO/Virgo/KAGRA S240925n: Updated Sky localization
- NuEm-240926A: Upper limits from a search for coincident neutrino events in IceCube
- GRB241001A: REM optical/NIR upper limits
- LIGO/Virgo/KAGRA S241002e: Updated Sky localization
- GRB 241002A: Swift/UVOT Upper Limits
- EP240930a: Liverpool Telescope observations
- GRB 241002A: Swift-XRT refined Analysis
- GRB 241002A: LCOGT Optical Upper Limits
- GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
- GRB 241001A: Swift/UVOT Detection
- GRB 240929A: Liverpool Telescope prompt followup observations
- GRB 241001A: Swift-XRT observations
- GRB241001A: optical afterglow candidate
- GRB 241002A: Enhanced Swift-XRT position
- GRB 241001A: BOOTES-6/DPRT optical upper limit
- LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
- GRB 241002A: Swift detection of a burst
- LIGO/Virgo/KAGRA S240930du: Updated Sky localization
- GRB 240930B: Fermi GBM Observation
- GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
- Fermi-LAT Gamma-ray Observations of IceCube-240929A
- EP240930a: EP-WXT detection of a fast X-ray transient
- SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
- LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
- IceCube-240929A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S240930df: 1 counterpart neutrino candidate event from an IceCube neutrino search
- AMON NuEM 240926A: Swift XRT Follow-up
- GRB 240929A : Leavitt Observatory optical upper limit
- GRB 240825A: LBT optical observations
- GRB 240928A: SVOM/GRM observation
- LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
- Fermi trigger No 749339671: Global MASTER-Net observations report
- GRB 240929A long GRB detected by INTEGRAL
- GRB 240929A: BALROG localization (Fermi Trigger 749332209 / GRB 240929826)
- Swift Trigger 1256950 is probably not a GRB
- LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
- NuEm-240926A / IC240926A: BZQJ0955+4532 ~0.6m optical decay and rebrightening detection by MASTER
- GRB 240926A: SVOM/GRM observation
- Konus-Wind detection of GRB 240905B
- EP240919a / GRB 240919A: SVOM/VT upper limit
- LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
- EP240918b and EP240918c: EP-FXT follow-up observations
- LIGO/Virgo/KAGRA S240925n: Updated Sky localization and Source Classification
- Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
- GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
- LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
- GRB 240905B: VZLUSAT-2 detection
- LIGO/Virgo/KAGRA S240922df: Updated Sky localization
- LIGO/Virgo/KAGRA S240920dw: Updated Sky localization
- LIGO/Virgo/KAGRA S240921cw: Updated Sky localization
- LIGO/Virgo/KAGRA S240924a: Updated Sky localization
- LIGO/Virgo/KAGRA S240920bz: Updated Sky localization and Source Classification
- LIGO/Virgo/KAGRA S240923ct: Updated Sky localization and Source Classification
- 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 S240919bn: Swift XRT observations, 10 X-ray sources
- GRB 240918B: AstroSat CZTI detection
- LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
- EP240913A/GRB 240913C: AbAO optical upper limit
- EP240919a / GRB 240919A: Mondy optical upper limit
- EP240913a/GRB 240913C: 1.6m Mephisto observations
- EP240918a: SVOM/VT upper limit
- Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
- EP240919a / GRB 240919A: REM optical and NIR upper limits
- EP240918b and EP240918c: Optical upper limits with Kinder observations
- GRB 240414A: further radio observations with the VLA
- EP240919a: Optical upper limit with Kinder observations
- LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
- GRB 240910A: radio detection with the VLA