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"
24643 results found.
- GRB 241025A: Swift-XRT refined Analysis
- GRB 241025C: Fermi GBM Detection
- GRB 241025A: Fermi GBM Observation
- IPN triangulation of GRB 241022A (short/hard)
- LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
- EP 241021a: Swift-XRT observations
- GRB 241025A : SVOM/VT optical afterglow observations
- EP241021a: Liverpool Telescope optical follow-up observations
- GRB 241025A: Enhanced Swift-XRT position
- GRB 241025A: DDOTI Afterglow detection
- GRB 241025A: TRT optical afterglow observation
- GRB 241025A: Swift detection of a burst with an optical counterpart
- EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
- GRB 241001A: ATCA radio observations
- GRB 241010A: VIRT Optical Upper Limit
- EP241021a: SAO RAS optical observations
- EP241021a: KAIT optical observations
- EP241021a: 1.3m DFOT Optical observations
- EP241021a: GSP detects optical candidate counterpart
- EP241021a: Optical upper limits with Kinder observations
- EP241021a: TRT optical observations
- GRB 241018A: SVOM/C-GFT optical observations
- EP241021a: NOT likely optical counterpart
- EP EP241021a: Global MASTER-Net observations report
- GRB241017A: 1.3m DFOT optical upper limit
- GRB 241018A: 1.3m DFOT Optical upper limit
- EP241021a: GOTO optical upper limits
- EP241021a: EP detection of a fast X-ray transient
- IceCube-Cascade 241019A: Upper limits from a search for additional neutrino events in IceCube
- GRB 241018A/sb24101802: Mephisto optical upper limit
- GRB 241017A/sb24101702: Mephisto optical upper limit
- GRB 241018A: Mondy optical upper limit
- GRB 241018A: SVOM/VT further analysis and counterpart confirmed
- GRB 241018A: GROWTH-India telescope optical upper limit
- GRB241018A: XingLong Optical Upper Limit
- GRB 241018A: Swift-XRT observations
- GRB 241018A: REM optical/NIR upper limits
- GRB 241018A: NOT optical observations
- GRB 241018A: SVOM/VT follow-up and optical candidate
- GRB 241018A: LCO/0.4m optical upper limits
- GRB 241006A: VIRT Optical Upper Limit
- GRB 240727A: VIRT Optical Upper Limit
- GRB 241018A: X-ray afterglow candidate observed by MXT
- GRB 241017A: Swift-XRT observations
- GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
- GRB 241001A: EP-FXT afterglow detection
- GRB 241017A: GROWTH-India Telescope optical upper limit
- GRB241017A: TOO Observations by SVOM/MXT
- GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
- GRB 241017A: J-band upper limit from WINTER
- GRB 241016B: SVOM/GRM observation
- GRB 241017A : Detection of a weak and soft long duration GRB by SVOM/ECLAIRs
- GRB 241010A: Swift-BAT refined analysis
- GRB 241013B: Fermi GBM Observation
- GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
- GRB 241013A: Fermi GBM Observation
- GRB 240916A: radio detection with the VLA
- GRB241013A: REM observations
- GRB 241009A: LCO optical upper limits
- Integral GRB241013.04: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S241009em: Updated Sky localization
- LIGO/Virgo/KAGRA S241011k: Updated Sky localization
- LIGO/Virgo/KAGRA S241011k: NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S241011k: Identification of a GW compact binary merger candidate
- GRB 241009A: GRANDMA optical upper limits
- GRB 241009A: Swift-XRT afterglow detection
- GRB 241010A: JinShan optical observations and potential host galaxy
- GRB 241010A: Swift-XRT refined Analysis
- LIGO/Virgo/KAGRA S241007bw: Updated Sky localization
- Fermi trigger No 750211959: Global MASTER-Net observations report
- Fermi trigger No 750291012: Global MASTER-Net observations report
- GRB 241010A: J-band observations with WINTER
- LIGO/Virgo/KAGRA S241009an: Updated Sky localization
- IceCube-241006A: Upper limits from a search for additional neutrino events in IceCube
- GRB 241010A: Enhanced Swift-XRT position
- GRB 241010A: LCO optical observations
- GRB 241010A: Swift detection of a burst with an optical counterpart
- Fermi-LAT Gamma-ray Observations of IceCube-241006A
- GRB 241006A: Swift-BAT refined analysis
- LIGO/Virgo/KAGRA S241009l: Updated Sky localization
- LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
- GRB 241008A: Fermi GBM Observation
- GRB 241002B: Swift-XRT afterglow detection
- LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
- GRB 241002A: NOT optical upper limits
- LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
- GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
- IceCube-241006A: No candidates from the Zwicky Transient Facility
- GRB 241006A: GRANDMA optical upper limits
- GRB 241002B: PRIME near-infrared detection in 3rd epoch
- 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