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').
16007 results found.
- GRB 240218A: Swift detection of a burst
- GRB 240213A: Glowbug gamma-ray detection
- GRB 240128A: Further Swift-XRT observations
- GRB 240209A: NOT photometry of the AT2024cew / GOTO24pw counterpart candidate
- IPN triangulation of GRB 240205A (short)
- GRB 240205B: PRIME near infrared detection
- GRB 240205A (short): Glowbug gamma-ray detection
- GRB240204A: Swift/UVOT Upper Limits
- GRB 240205B: AstroSat CZTI detection
- GRB 240205B: VLT/X-shooter redshift
- GRB 240205B: REM detection of the optical/NIR afterglow
- GRB 240204A : OHP/T193/T120 optical afterglow fading detection
- GRB 240205B: Skynet Optical Afterglow Observations
- GRB 240204a: Liverpool Telescope optical afterglow detection
- GRB 240204A: Osservatorio Astronomico Nastro Verde upper limit
- IceCube-240204A: Upper limits from a search for additional neutrino events in IceCube
- GRB 240204A: optical afterglow detection with LCOGT 1m telescopes at Sutherland and Teide Observatories
- GRB 240204A: Montarrenti Observatory optical observations
- GRB 240204A: Enhanced Swift-XRT position
- GRB 240204A: Mondy optical afterglow candidate
- GRB 240204A: Swift detection of a burst
- GRB 240204A: Fermi GBM Final Real-time Localization
- IPN triangulation of GRB 240124B
- GRB 240201A: AstroSat CZTI detection
- GRB 240128A: Glowbug gamma-ray detection
- IceCube-240123A: Upper limits from a search for additional neutrino events in IceCube
- GRB240122A: PRIME near infrared detection
- GRB 240123A: Glowbug gamma-ray detection
- GRB 240125A (short): Glowbug gamma-ray detection
- IPN triangulation of GRB 240123C (short)
- GRB 240123A: further SAO RAS optical observations
- GRB 240123A: SAO RAS optical observations
- GRB 240123A : MITSuME Akeno optical afterglow candidate detection
- GRB 240123A: Enhanced Swift-XRT position
- GRB 240122A: Swift/UVOT Upper Limits
- GRB 240118A: Swift/UVOT Upper Limits
- GRB 240122B: Glowbug gamma-ray detection
- GRB 240123A: Mondy optical afterglow observations
- GRB 240123A: Swift detection of a burst with a possible optical counterpart
- GRB 240122A: Swift-XRT afterglow detection
- GRB 240122A: VLT/X-shooter redshift confirmation
- IPN triangulation of GRB 240119A (short)
- GRB 240118A: Mondy optical observations
- GRB 240118A: Swift-XRT afterglow detection
- IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
- AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-240118A: correction on the localization
- GRB 240118D: AstroSat CZTI detection
- GRB 240117A: AstroSat CZTI detection
- GRB 240118A: AbAO optical upper limit
- GRB 240117A: Glowbug gamma-ray detection
- Konus-Wind detection of GRB 240118A
- GRID detection of GRB 231230A
- GRB 240115B: AstroSat CZTI detection
- GRB 240112D: Glowbug gamma-ray detection
- GRB 240112C: Glowbug gamma-ray detection
- Konus-Wind detection of GRB 240112C
- GRB 240112C: Swift/UVOT Detection
- GRB 240112C: Swift-XRT refined Analysis
- GRB 240112C: SAO RAS optical observations
- GRB 240112C: Swift detection of a burst with an optical counterpart
- GRB 240110A: AstroSat CZTI detection
- GRB 240108A: Glowbug gamma-ray detection
- GRB 240106B: Glowbug gamma-ray detection
- GRB 240106A: Glowbug gamma-ray detection
- IceCube-240105A: Upper limits from a search for additional neutrino events in IceCube
- Konus-Wind detection of GRB 240101C
- GRB 231215A: radio detection with the VLA
- GRB 230818A: further radio observations with the VLA
- GRB 230812B: further radio observations with the VLA
- GRB 240107A: AstroSat CZTI detection
- LIGO/Virgo/KAGRA S240109a: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S240107b: Identification of a GW compact binary merger candidate
- IPN triangulation of GRB 240101C (short)
- GRB 240101A: 1.3m DFOT optical observations
- GRB 240102A: 1.3m DFOT optical upper limit
- GRB 240101B: 1.3m DFOT optical upper limit
- GRB 240102C: AstroSat CZTI detection
- GRB 240102A: Swift/UVOT Upper Limits
- GRB 240102A: Enhanced Swift-XRT position
- GRB 240102A: Swift-XRT refined Analysis
- GRB 240102A: LCOGT Optical Upper Limits
- GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
- IceCube-Cascade 231230A: Upper limits from a search for additional neutrino events in IceCube
- GRB 240102A: Swift detection of a burst
- GRB 240101B: Swift/UVOT Upper Limits
- GRB 240101A: Swift/UVOT Upper Limits
- GRB 240101B: Enhanced Swift-XRT position
- GRB 240101A: Enhanced Swift-XRT position
- GRB 240101B: Swift detection of a burst
- GRB 231230A: Enhanced Swift-XRT position
- GRB 231230A: Swift/UVOT Upper Limits
- GRB 231230A: NOT optical upper limits
- GRB 231230A: Swift detection of a burst
- LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
- GRB 231222B: Swift-XRT afterglow detection
- LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
- IceCube-231211A: GRANDMA observations of PKS2047+098
- GRID detection of GRB 231215A
- GRID detection of GRB 231205B