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"- GRB091018: Magellan Echellette Observations
- GRB 091018: Enhanced Swift-XRT position
- GRB 091018: ROTSE-III Detection of Optical Counterpart
- GRB 091015: Skynet/PROMPT Observations
- GRB 091018: Swift detection of a burst with optical afterglow
- Fwd: GRB 091003: Possible Supernova Component Retraction
- GRB 091003: Possible Supernova Component
- GRB 091003: Gemini-N redshift of possible host galaxy
- GRB 091010: optical obsevation
- GRB 091015: RTT150 optical observations
- GRB 090726 R band observations
- GRB 091010: optical afterglow candidate rejection
- GRB 091015: correction to GCN 10025
- GRB 090815: a faint long GRB localized by INTEGRAL
- GRB 091010: Swift-XRT refined analysis
- GRB 091010: Suzaku WAM observation of the prompt emission
- GRB 091010: AGILE-MCAL measurement and GRID upper limit
- Radio observation of GRB090927 with ATCA
- Radio observation of GRB090926a with ATCA
- Radio observation of GRB080916c with ATCA
- GRB 091010: Fermi GBM observation
- GRB 091010: Faulkes Telescope North observations
- GRB 090531A: Skynet/PROMPT Observations
- GRB 090530A: Skynet/DSO Detections
- GRB 091010: RXTE detection
- Konus-Wind observations of GRB 091010
- GRB 091010: Enhanced XRT position
- GRB 091010 optical upper limits
- Detection of a short GRB 090929A by RT-2 Experiment
- RT-2 observation of the bright GRB 090926A
- GRB 091010: GROND afterglow candidate
- GRB 091010: Swift/UVOT Upper Limits
- GRB 091010: Swift-XRT position
- SuperAGILE GRB is 091010 and not 090910
- GRB 090910: SuperAGILE Localization of a Long GRB
- GRB 090926A: Skynet/PROMPT Observations of Day 6 - 11 Fading
- GRB 090518: Skynet/PROMPT Observations
- Short-Duration GRB 090621: Skynet/Dolomiti Observations
- GRB 090904A: afterglow confirmation
- GRB 090812: Skynet/PROMPT and GORT Observations
- GRB 091003A: Suzaku WAM observation of the prompt emission
- GRB 091003: Lick observations and possible SDSS host galaxy
- GRB 090926B: Skynet/PROMPT Observations
- GRB 091003: WHT ACAM observations
- Konus-Wind observation of GRB 091003A
- GRB 090929B: Suzaku WAM observation of the prompt emission
- GRB 090929A: Suzaku WAM observation of the prompt emission
- GRB 091003: Swift-XRT confirmation of fading afterglow
- GRB 091003: Swift/UVOT Detection of an Optical Afterglow
- GRB 091003: Skynet/DSO Observations
- GRB 091003: UVOT-enhanced XRT position
- GRB 091003: Swift UVOT Detection of a Candidate UV Afterglow
- GRB 091003: Swift XRT analysis
- GRB 091003A: Fermi LAT detection
- GRB 090926A: Skynet/PROMPT Observations of Day 4 - 6 Fading Rate
- GRB 091003A: Fermi GBM detection
- GRB 090926A: Skynet/PROMPT Observations of Post-Peak Fading
- GRB 090929A: Swift/UVOT Observations
- GRB 090929A, Swift-BAT refined analysis
- GRB 090929B, Swift-BAT refined analysis
- Trigger 371210: Swift/BAT Triggered on IGR J17511-3057
- GRB 090929A: Swift-XRT non-detection
- Konus-Wind observation of GRB 090929A
- Konus-Wind observation of GRB 090929B
- GRB 090927: Fermi GBM observation
- GRB 090929B: Swift-XRT refined analysis
- GRB 090926A: Fermi LAT and GBM refined analysis
- GRB 090929B: Gemini-N upper limits
- GRB 090929B: Skynet/DSO Observations
- GRB 090929B: Swift/UVOT Observations
- Konus-RF observation of GRB 090929A
- GRB 090929B: RAPTOR Discovery of Optical Counterpart
- GRB 090929A BAT location of the Fermi GBM burst
- Correction: GRB 090929B: Enhanced Swift-XRT position
- GRB 090929: Enhanced Swift-XRT position
- GRB 090929B: Swift detection of a burst
- GRB 090929A: Fermi GBM detection
- GRB090926A: Swift-XRT refined analysis
- GRB 090927: Faulkes Telescope South Detection of the Optical Afterglow
- Konus-Wind and Konus-RF observations of GRB 090926A
- GRB 090927: VLT redshift
- GRB 090926B: Fermi GBM detection
- GRB 090927: Zadko Telescope observations
- GRB 090927, Swift-BAT refined analysis of the possibly short burst
- Swift/UVOT observations of GRB 090927
- GRB 090926A: Skynet/PROMPT Continued Observations
- GRB 090927: Swift XRT refined analysis
- GRB 090926A: Suzaku WAM observation of the prompt emission
- GRB 090927: Enhanced Swift-XRT position
- GRB090926B: Swift/UVOT Upper Limits
- GRB090926A: Swift/UVOT observations
- GRB 090926B: VLT spectroscopy
- GRB 090927: Swift/UVOT detection of an optical afterglow
- GRB 090927: Swift detection of a short burst
- GRB 090926B: optical object in error circle
- GRB 090926B: MAXI GSC detection
- GRB 090926A: VLT/X-shooter redshift
- GRB 090926B: NOT optical observation
- GRB 090926B: Swift XRT refined analysis
- GRB 090926B: Swift-BAT refined analysis