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"
32167 results found.
- GRB 241008A: Fermi GBM Observation
- GRB 241008A: Fermi-LAT detection
- GRB 241002B: Swift-XRT afterglow detection
- GRB 241002A: NOT optical upper limits
- Fermi GRB 241008A: Global MASTER-Net observations report
- GRB 241008A: BALROG localization (Fermi Trigger 750117609 / GRB 241008917)
- GRB 241008A: Fermi GBM Final Real-time Localization
- GRB 241006A: GRANDMA optical upper limits
- EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
- GRB 241002B: PRIME near-infrared detection in 3rd epoch
- GRB 240910A: LBT optical observations
- EP trigger ID 01709065118: KAIT confirmation of the stellar flare
- 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
- GRB 241006A: SVOM/VT follow-up and optical upper limit
- 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
- GRB 241004A: SVOM/GRM observation
- GRB 240930B / EP 240930a: SVOM/GRM observation
- 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 241002B: Swift ToO observations
- GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
- Konus-Wind detection of GRB 240926A
- GRB 241002B: PRIME near-infrared detection
- GRB 241002C: Swift ToO observations
- Fermi-GBM Sub-Threshold Detection of GRB 241002D
- IPN triangulation of GRB 240930B / EP 240930a
- GRB 241001A : SVOM/VT optical detection
- GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
- GRB 241002D: SVOM/GRM observation
- GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
- GRB 240930B: CALET Gamma-Ray Burst Monitor detection
- 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
- GRB241001A: REM optical/NIR upper limits
- GRB 241002A: Swift/UVOT Upper Limits
- 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 241001A: VLT/X-shooter redshift
- GRB 241002B: GOTO optical counterpart candidate
- GRB 241002C : Detection of a long soft transient by SVOM/ECLAIRs
- GRB 241001A: correction to GCN 37667
- GRB 240929A: Liverpool Telescope prompt followup observations
- Fermi GRB 241002B: Global MASTER-Net observations report
- GRB 241001A: Swift-XRT observations
- GRB 241002B: Fermi GBM Final Real-time Localization
- GRB241001A: optical afterglow candidate
- GRB 241002A: 1.5m OSN optical upper limit
- GRB 241002A: Enhanced Swift-XRT position
- GRB 241001A: BOOTES-6/DPRT optical upper limit
- GRB 241002A: Swift detection of a burst
- GRB 240930B: Fermi GBM Observation
- GRB 241001A: Swift ToO observations
- GRB 240930B: GRBAlpha detection
- GRB 240929A: GRBAlpha detection
- EP240930a : KAIT optical upper limit
- GRB 241001A : Detection of a soft transient by ECLAIRs onboard SVOM
- GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
- EP240930a: EP-FXT follow-up observation update
- EP240930a: GOTO optical upper limits
- GRB 240929A: SVOM/GRM observation
- EP240930a: EP-WXT detection of a fast X-ray transient
- GRB 240929A : Leavitt Observatory optical upper limit
- Fermi GRB 240930B: Global MASTER-Net observations report
- GRB 240930B: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 240926A
- GRB 240825A: LBT optical observations
- GRB 240928A: SVOM/GRM observation
- Fermi GRB 240930A: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 749362078/240930172 (GRB 240930A) is not a GRB
- GRB 240930A: Fermi GBM Final Real-time Localization
- Fermi Gamma-ray Burst Monitor trigger 749339671/240929913 is not a GRB
- GRB 240929A long GRB detected by INTEGRAL
- GRB 240929A: BALROG localization (Fermi Trigger 749332209 / GRB 240929826)
- Fermi GRB 240929A: Global MASTER-Net observations report
- GRB 240929A: Fermi GBM Final Real-time Localization
- Konus-Wind detection of GRB 240912A
- Swift Trigger 1256950 is probably not a GRB
- Fermi Gamma-ray Burst Monitor trigger 749191601/240928199 is 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
- EP trigger ID 01709059262: Lick/Kast spectroscopy with 3 m Shane telescope
- GRB 240926A: SVOM/GRM observation
- Konus-Wind detection of GRB 240905B
- GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
- EP240919a / GRB 240919A: SVOM/VT upper limit