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.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
- GRB 241030A: Fermi GBM Observation
- EP241021a: AMI-LA radio detection
- GRB 241030B : GIT optical upper limits
- GRB 241030B: LCOGT Optical Upper Limits
- GRB 241030B: Swift-BAT refined analysis
- GRB 241030A: Swift-BAT refined analysis
- GRB 241029A: COLIBRI Detection of the Optical Counterpart
- GRB 241030B: Swift/UVOT Detection
- EP EP241030a: Global MASTER-Net observations report
- GRB 241029A: LCO optical detection
- Fermi trigger No 752006065: Global MASTER-Net observations report
- GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
- Swift GRB241030.77: Global MASTER-Net observations report
- GRB 241030B: SVOM/GRM observation
- GRB 241030B : MITSuME Akeno optical upper limits
- GRB 241030A: COLIBRI Continuing Detection of the Afterglow
- GRB 241030B: SVOM/VT optical afterglow observations
- GRB 241030B: COLIBRÍ Upper Limits on the Optical Counterpart
- EP241030a: EP detection of GRB 241030A X-ray Afterglow
- GRB241030B: Fermi GBM Observation
- GRB 241030B: BTA observations
- GRB 241029A: SVOM/VT optical afterglow observations
- GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
- GRB 241030B: Enhanced Swift-XRT position
- GRB 241030B: optical observations from the INAF Asiago Observatory
- EP241021a: Swift-UVOT detection
- 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: SVOM/ECLAIRs detection of a burst
- GRB 241030B: Prompt enhanced Swift-XRT position
- Konus-Wind detection of GRB 241030A
- GRB 241030B: Swift detection of a burst
- GRB 241030B: Fermi GBM Final Real-time Localization
- GRB 241030A: Fermi-LAT detection
- GRB 240912A: radio detection with the VLA
- Fermi GRB 241030A: Global MASTER-Net observations report
- GRB 241030A: AKO Optical Afterglow Detection
- Swift GRB 241030A: Global MASTER-Net observations report
- GRB 241030A: Swift/UVOT Detection
- EP 241021a: further Swift-XRT observations and X-ray counterpart detection
- GRB 241030A: SVOM/GRM observation
- GRB 241026A: Swift-BAT refined analysis
- GRB 241030A: SVOM/C-GFT optical observations
- GRB 241026A: LBT optical observations
- EP241021a: Optical rebrightening observations with Mephisto
- EP241026b: EP-FXT follow-up observation
- GRB 241030A: Multiband optical detection with Mephisto
- GRB 241030A: SVOM/VT optical afterglow observations
- GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
- GRB 241030A : MITSuME Akeno optical afterglow detection
- GRB 241030A: Enhanced Swift-XRT position
- GRB 241029A: GROWTH-India Telescope optical follow up
- GRB 241030A: TRT optical observations
- GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
- 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 241030A: Fermi GBM Final Real-time Localization
- GRB 241029A: SAO RAS optical observations
- GRB 241026A: SAO RAS optical observations
- EP240919a / GRB 240919A: ATCA Detection of Radio Counterpart
- EP241021a: SAO RAS observations of rebrightening
- GRB 241029A: GTC/OSIRIS+ spectroscopic redshift z=1.072
- EP241021a: ATCA radio observations
- 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
- GRB 241029A: GOTO optical afterglow detection
- EP241021a: continued SOAR observations confirm optical rebrightening
- GRB 241029A: MASTER early optical counterpart detection
- 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 241029A: Swift ToO observations
- GRB 241029A: SVOM/GRM observation
- GRB 241029A : Detection and localization of a bright long GRB by SVOM/ECLAIRs
- Fermi trigger No 751861204: Global MASTER-Net observations report
- GRB 241029A: Fermi GBM Final Real-time Localization
- GRB 240821A: Keck/LRIS spectroscopic observations
- EP241021a: Gemini-South detection of optical rebrightening
- GRB 241026A: the 100th GRB detected by GRBAlpha
- GRB 241026A: TNOT optical counterpart detection
- Konus-Wind detection of GRB 241025A
- GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
- GRB 241026A: LBT redshift confirmation
- GRB 241026A: GECAM detection
- 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: BTA redshift identification of z = 2.79