GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. 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').
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"- GRB 201221D: near-infrared observation with LBT
- ZTF21aaeyldq: NOT optical observations
- ZTF21aaeyldq: Lowell Discovery Telescope observations
- ZTF21aaeyldq: observations with the 3.6m Devasthal Optical Telescope
- ZTF21aaeyldq: GTC Redshift and GRB afterglow nature confirmation
- GRB 201015A: evidence of supernova in LBT spectra
- ZTF Discovery of ZTF21aaeyldq (AT2021any): a Hostless, Young, and Rapidly Fading Transient
- GRB 210104A: JCMT SCUBA-2 sub-mm observations
- GRB 210112A: Swift/UVOT Detection
- GRB 210112A: Mondy optical observations
- GRB 210112A: 1.3m DFOT Optical upper limit
- GRB 210112A: OSN second epoch, decay
- GRB 210104A: AstroSat CZTI detection
- NuEm-210111A: MAXI/GSC upper limit
- GRB 210112A: Swift-BAT refined analysis
- GRB 210112A: OSN Reddened Afterglow Detection
- GRB 210112A: Swift-XRT refined Analysis
- NuEm-210111A : No neutrino counterpart in ANTARES
- GRB 210112A: AGILE detection
- GRB 210112A: Kitab a optical upper limit
- GRB 210104A: AROMA-N Optical Afterglow Detection
- GRB 210112A: Enhanced Swift-XRT position
- GRB 210112A: Swift detection of a burst with an optical counterpart
- NuEm-210111A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-210111A
- GRB 210104A: Mondy optical observations, light curve
- MAXI GRB210110.64: Global MASTER-Net observations report
- GRB 210110A: MAXI/GSC detection
- GRB 210104A: Assy continued optical observations, correction to GCN circ. 29265
- GRB 210109A: MAXI/GSC detection
- GRB 201227A: continued Chilescope confirmation of variability of possible optical counterpart, redshift estimating
- Correction to GCN 29278: GRB 201216C XRT refined analysis
- GRB 210108A: BALROG localization (Fermi Trigger 631793415 / GRB 210108424)
- GRB 201216C: Swift-XRT refined Analysis
- GRB 210104A: SAO RAS optical observations
- GRB 201227A: ASIM observation
- GRB 210104A: GMG observations
- GRB210104A: VIRT optical transient detection.
- GRB 210104A: SARA-KP 0.9m Optical Afterglow Detection
- Fermi trigger No 631602681: Global MASTER-Net observations report
- GRB 210102B: further Swift-XRT observations
- GRB 210102B: Assy optical afterglow identification
- GRB 210104A: iTelescope optical upper limit
- GRB 210104A: CALET Gamma-Ray Burst Monitor detection
- Fermi trigger No 631584650: Global MASTER-Net observations report
- GRB 210104B: Swift-BAT refined analysis
- GRB 210104A: Assy continued optical observations
- Fermi GRB 210105A: Global MASTER-Net observations report
- GW170817: HST observations at 3.4 years from merger
- GRB 210104A: early ATLAS detections of the bright afterglow
- GRB 210105A: Fermi GBM Final Real-time Localization
- GRB 210104A: Swift-XRT refined Analysis
- GRB 210104B: Swift/UVOT Upper Limits
- Konus-Wind detection of GRB 210104A
- GRB 210104A: 1.3m DFOT Optical Afterglow Detection
- GRB 210104B: Swift-XRT refined Analysis
- GRB 210104B: Assy optical upper limit
- GRB 210104A: DOAO optical afterglow observations
- GRB 210104B: Enhanced Swift-XRT position
- GRB 210104A: Nanshan/NEXT optical powerlaw decay
- GRB 210104A: Swift-BAT refined analysis
- GRB 210104B: Nanshan/NEXT optical upper limit
- GRB 210104B: BOOTES network optical upper limit
- GRB 210104A: MASTER OT rebrightening detection
- GRB 210104A: Swift/UVOT Detection
- GRB 210104A: Fermi GBM detection
- GRB 210104A: Enhanced Swift-XRT position
- GRB 210102B: Tiled Swift observations
- GRB 210104B: Swift detection of a burst
- Swift GRB210104.88: Global MASTER-Net observations report
- GRB 210104A: MITSuME Ishigaki optical observation
- GRB 210102B: Assy optical observations
- Fermi GRB 210104A: Global MASTER-Net observations report
- GRB 210104A: Assy optical observations
- GRB 210104A: MITSuME Akeno optical observation
- GRB 210104A: BOOTES-4/MET early optical afterglow detection
- GRB 210104A: GWAC-F60A optical afterglow observations
- GRB 210104A: BALROG localization (Fermi Trigger 631452424 / GRB 210104477)
- GRB 210104A: Swift detection of a burst with a bright optical counterpart
- GRB 210104A: Fermi GBM Final Real-time Localization
- GRB 210102C: Swift-BAT refined analysis
- GRB 210102B: Swift-XRT observations
- Fermi GRB 210102C: Global MASTER-Net observations report
- GRB 210102C: Fermi GBM detection
- Swift GRB 210102C: Global MASTER-Net observations report
- GRB 210102C: Swift detection of a burst
- MAXI GRB210102.38: Global MASTER-Net observations report
- GRB 210102B: Tiled Swift observations
- GRB 210102B: MAXI/GSC detection
- Fermi GRB 210101A: Global MASTER-Net observations report
- INTEGRAL Weak #8913: AROMA-N Optical Observation
- Swift Trigger 1015615 is not a GRB
- Swift GRB210102.01: Global MASTER-Net observations report
- Fermi trigger No 631226368: Global MASTER-Net observations report
- Fermi trigger No 631119348: Global MASTER-Net observations report
- GRB 210101A: BALROG localization (Fermi Trigger 631205591 / GRB 210101620)
- GRB 210101A: Fermi GBM Final Real-time Localization
- Fermi trigger No 631113166: Global MASTER-Net observations report
- GRB 201229A: Swift/UVOT Detection
- Fermi trigger No 631118376: Global MASTER-Net observations report