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"19093 results found.
- GRB 180624A: Swift/UVOT Upper Limits
- GRB 180624A: Enhanced Swift-XRT position
- GRB 180624A: Swift detection of a burst
- GRB 180623A: Swift/UVOT Detection
- GRB 180623A: Enhanced Swift-XRT position
- GRB 180623A: Swift detection of a burst
- GRB 180620B: Swift/UVOT Detection
- GRB 180620A iTelescope observation
- GRB 180613A: Afterglow confirmation and added photometry
- GROND observations of GRB 180620B
- GROND observations of GRB 180620A
- GRB 180620B: Enhanced Swift-XRT position
- GRB 180620A: Xinglong-2.16m optical observations
- GRB 180618A: Swift/UVOT Detection
- GRB 180618A: TSHAO optical upper limit
- GRB 180620B: Swift detection of a burst with an optical counterpart
- GRB 180620A: COATLI Detection and Light Curve
- GRB 180620A: Swift/UVOT Detection
- GRB 180618A: Xinglong-2.16m optical upper limit
- GRB 180620A: Enhanced Swift-XRT position
- GRB 180620A: ISON-MN afterglow confirmation
- GRB 180620A: RATIR Optical Afterglow Detection
- GRB 180620A: Swift detection of a burst with an optical counterpart
- GRB 180618A: Enhanced Swift-XRT position
- GRB 180618A: Swift detection of a burst with an optical counterpart
- GRB 180614A: AbAO optical observations
- GRB 180614A: Swift/UVOT Upper Limits
- GRB 180614A: NOT optical upper limits
- GRB 180614A: Enhanced Swift-XRT position
- GRB 180614A: Swift detection of a burst
- GRB 180613A: Swift/UVOT Upper Limits
- GRB 180613A GROND observations
- GRB 180613A: Possible IR afterglow
- GRB 180613A: Enhanced Swift-XRT position
- GRB 180613A: Possible host galaxy at XRT position, or star
- GRB 180613A: Swift detection of a burst
- GW170817/GRB170817A: LBT optical detection
- GRB 180602A: Swift/UVOT Upper Limits
- GRB 180602A: MITSuME Akeno optical upper limits
- GRB 180602A: MITSuME Okayama optical upper limits
- GRB 180602A: Enhanced Swift-XRT position
- GRB 180602A: Swift detection of a burst
- IPN Triangulation of GRB 180529A (short/hard)
- Swift Trigger 834937 is not a GRB
- IPN Triangulation of GRB 180523A
- GRB180523B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 548793993)
- GRB 180514A: CrAO/ZTSH optical observations and afterglow candidate
- GRB 180514A: Swift/UVOT Upper Limits
- GRB 180514A: Detection limits from 2.5m NOT
- GRB 180510A: MITSuME Ishigakijima optical upper limits
- GRB 180514A: 1.5m OSN optical observations
- GRB 180514A: GOTO Optical Observations
- GRB 180514A: Swift-BAT refined analysis
- GRB 180514A: Enhanced Swift-XRT position
- GRB 180512A: VLT/HAWK-I NIR Observations
- GRB 180514A: Swift detection of a burst
- GRB 180512A: RATIR Optical Observations
- GRB 180512A: LBT optical detection
- GRB 180512A: Swift/UVOT Upper Limits
- GRB 180512A: Enhanced Swift-XRT position
- GRB 180512A: GROND upper limits
- 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
- Swift trigger 831888: misidentification of 4U 1416-62
- 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
- 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: ePESSTO NTT NIR observations
- GRB 180504A: Swift-XRT refined Analysis
- GRB 180504A: NOT afterglow candidate
- GRB 180504A: Swift detection of a burst
- IPN Triangulation of GRB 180427A
- Swift Trigger 829046 is probably noise
- 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
- GRB 180418A : SQUEAN observations
- 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: Gemini-North imaging and spectroscopy
- GRB 180418A: RATIR Optical Observations
- LIGO/Virgo G299232: LOFAR follow-up
- GRB 180418A: Enhanced Swift-XRT position
- GRB 180418A: Swift-XRT observations