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').
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 180512A: NOT upper limits
- GRB 180512A: OASDG optical observations
- GRB 180512A: Upper limits from OSN
- GRB 180512A: Swift detection of a burst
- GRB 180510A: Swift/UVOT followup observations
- GRB 180510B: Swift-XRT refined Analysis
- GRB 180510A: Swift-XRT refined Analysis
- Swift trigger 831888: misidentification of 4U 1416-62
- GRB 180510B: Swift-BAT refined analysis
- GRB 180510B: VLT/X-shooter observations
- GRB 180510B: GROND detection in all bands
- GRB 180510B: TAROT La Silla observatory optical observations
- Swift Trigger 831888: a possible GRB or Galactic transient
- GRB 180510B: Enhanced Swift-XRT position
- GRB 180418A: 15 GHz upper limits from AMI
- GRB 180510B: Swift detection of a burst with an optical counterpart
- GRB 180510A: Swift detection of a burst
- GRB 180427A: AstroSat CZTI detection
- Chandra observations of GW170817 reveal a fading afterglow
- Chandra observations of GW170817 260 days since merger: first statistically significant evidence for an X-ray decay
- GRB 180504A: Swift/UVOT Upper Limits
- GRB 180504A: Swift-BAT refined analysis
- GRB 180505A: Fermi GBM detection
- GRB 180416A: AstroSat CZTI detection
- GRB 180504A: ePESSTO NTT NIR observations
- Correction to Swift-XRT light curve fit for GRB 180504A in GCN 22685
- GRB 180504A: Swift-XRT refined Analysis
- GRB 180504A: NOT afterglow candidate
- GRB 180504A: Prompt enhanced Swift-XRT position
- GRB 180504A: Swift detection of a burst
- GRB 180416B: AstroSat CZTI detection
- Konus-Wind observation of GRB 180427A
- IPN Triangulation of GRB 180427A
- GRB 180427A: Fermi GBM detection
- Swift Trigger 829046 is probably noise
- GRB 180425A: Swift-XRT refined Analysis
- GRB 180425A: Swift-BAT refined analysis
- GRB 180425A: Swift/UVOT Upper Limits
- GRB 180425A: Enhanced Swift-XRT position
- GRB 180425A: Swift detection of a burst
- GRB 180418A: TAROT La Silla observatory early optical observations
- GRB 180418A: MITSuME Ishigakijima Optical Observation
- Retraction of IceCube GCN/AMON NOTICE 71165249_130949
- GRB 180418A : SQUEAN observations
- Fermi GBM trigger 545979055/180421202 is not a GRB
- GRB 180418A: Further GROND observations
- GRB 180418A: Swift/UVOT Detection
- GRB 180418A: Continued RATIR Optical Observations
- GRB 180418A: Imaging of the optical afterglow with the 1.3 m DFOT and 3.6 m DOT in ARIES, India
- GRB 180418A GROND observations
- GRB 180418A: Xinglong TNT optical upper limit
- GRB 180418A: NOT optical observations
- GRB 180418A: Gemini-North imaging and spectroscopy
- GRB 180418A: Swift-BAT refined analysis
- GRB 180418A: 1.5m OSN optical observations
- GRB 180418A: Fermi GBM observation
- GRB 180418A: Swift-XRT refined Analysis
- GRB 180416B: CALET Gamma-Ray Burst Monitor detection
- GRB 180418A: RATIR Optical Observations
- LIGO/Virgo G299232: LOFAR follow-up
- GRB 180418A: Enhanced Swift-XRT position
- GRB 180418A: Swift-XRT observations
- GRB 180418A: LCO FTN afterglow confirmation
- GRB 180418A: KAIT Optical Afterglow Candidate
- GRB 180418A: Swift detection of a short burst
- GRB 180404B: AstroSat CZTI detection
- GRB 180416A: Fermi GBM detection
- GRB 180409A: Swift-XRT afterglow detection
- GRB 180411A: CALET Gamma-Ray Burst Monitor detection
- GRB 180411B: CALET Gamma-Ray Burst Monitor detection
- Konus-Wind observation of GRB 180411A
- GRB 180411A: Swift/UVOT Upper Limit
- GRB 180411A: Tautenburg observations
- GRB 180410A: Fermi GBM observation
- GRB 180409A CALET Gamma-Ray Burst Monitor detection
- GRB 180411A: Fermi GBM detection
- GRB 180411A: Swift-BAT refined analysis
- GRB 180411A: Swift-XRT refined Analysis
- GRB 180410A: RATIR Optical Observations
- GRB 180411A: Swift detection of a burst
- GRB 180410A: Swift-XRT refined Analysis
- GRB 180410A: Swift-BAT refined analysis
- GRB 180410A: Swift/UVOT Upper Limits
- GRB 180409A: Fermi GBM observation
- GRB 180409A: Swift-XRT observations
- Konus-Wind observation of GRB 180404C
- GRB 180410A: MITSuME Akeno optical upper limits
- GRB 180410A: Enhanced Swift-XRT position
- Konus-Wind observation of GRB 180409A
- GRB 180410A: Swift detection of a burst or a Galactic transient.
- IPN Triangulation of GRB 180409A
- GRB 180409A: Tiled Swift observations
- GRB 180402A: ISON-NM early optical limits
- GRB 180407A: Swift-BAT refined analysis
- Swift Trigger 823014: TAROT Calern observatory optical observations
- GRB 180407A: COATLI Upper Limits
- Swift Trigger 823014 is probably not a GRB
- GRB 180407A: Swift detection of a burst
- GRB 180404B: Swift/UVOT Detection
- IPN Triangulation of GRB 180404C (long)