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"
24705 results found.
- GRB 241030B: Enhanced Swift-XRT position
- GRB241030B: GRANDMA/TAROT Upper Limit
- GRB 241030A: Swift-XRT refined Analysis
- GRB 241030B: SAO RAS optical observations
- GRB 241030B: AKO Optical Afterglow Detection
- GRB 241030B: Nanshan/HMT optical afterglow detection
- GRB 241030B: Swift detection of a burst
- GRB 240912A: radio detection with the VLA
- GRB 241030A: AKO Optical Afterglow Detection
- GRB 241030A: Swift/UVOT Detection
- EP 241021a: further Swift-XRT observations and X-ray counterpart detection
- GRB 241026A: Swift-BAT refined analysis
- GRB 241030A: SVOM/C-GFT optical observations
- GRB 241026A: LBT optical observations
- EP241021a: Optical rebrightening observations with Mephisto
- GRB 241030A: Multiband optical detection with Mephisto
- GRB 241030A: SVOM/VT optical afterglow observations
- GRB 241030A : MITSuME Akeno optical afterglow detection
- GRB 241030A: Enhanced Swift-XRT position
- GRB 241029A: GROWTH-India Telescope optical follow up
- GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
- GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
- GRB 241030A: Swift detection of a burst with a bright optical counterpart
- GRB 241029A: SAO RAS optical observations
- GRB 241026A: SAO RAS optical observations
- EP241021a: SAO RAS observations of rebrightening
- GRB 241029A: GTC/OSIRIS+ spectroscopic redshift z=1.072
- MISTRAL@OHP photometric and spectroscopic observations of GRB 241029A
- GRB 241026A: Swift/UVOT Upper Limits
- GRB 241029A: Swift-XRT observations
- GRB 241029A: Fermi GBM Observation
- GRB 241029A: AKO Optical Afterglow Detection
- EP241021a: continued SOAR observations confirm optical rebrightening
- GRB 241029A: Xinglong-2.16m optical afterglow confirmation
- GRB 241029A: Mephisto observations
- EP 241026b: LBT possible optical counterpart (brightening source)
- GRB 241029A: TRT optical afterglow candidate detection
- GRB 241026A: TNOT optical counterpart detection
- GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
- GRB 241025A: further SAO RAS optical observations
- GRB 241026A: BTA and Zeiss-1000 optical observations
- GRB 241026A: SVOM/GRM observation
- EP241026B: GROWTH-India Telescope optical upper limit
- GRB 241025A: Swift/UVOT Detection
- GRB 241026A: GROWTH-India Telescope optical observations
- GRB 241026A Fermi GBM Analysis
- GRB 241026A: J-band observations with WINTER
- GRB 241025A: SAO RAS optical observations
- GRB 241026A: Las Cumbres optical detection
- GRB 241025A: Mondy optical observations
- EP241021a: SOAR observations of the optical counterpart
- EP241021a: further SAO RAS optical observations
- GRB 241026A: Swift-XRT refined Analysis
- EP 241026b: LBT optical observations
- GRB 241026A: Enhanced Swift-XRT position
- EP241026b: EP detection of a fast X-ray transient
- GRB 241026A: COLIBRÍ Detection of the Optical Counterpart
- GRB 241026A: SAO RAS observations of possible optical afterglow
- GRB 241026A: Swift detection of a burst
- GRB241025A: 1.3m DFOT optical afterglow detection
- EP241021a: optical follow-up observations with Xinglong Observatory
- GRB 241025A: GROWTH-India Telescope optical observations
- GRB 241025A: COLIBRÍ Detection of the Afterglow
- 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