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 091208B: Keck HIRES redshift confirmation
- GRB 091208B: GROND observations
- GRB 091208A: Swift-XRT observations
- GRB091208B: NOT optical observations
- GRB 091208B: Swift-XRT refined analysis
- GRB091208B: Swift/UVOT refined analysis
- GRB 091208B: Fermi GBM observation
- GRB 091208B, Swift-BAT refined analysis
- GRB 091208A Swift-BAT refined analysis
- GRB 091208B: Gemini-North redshift
- GRB 091208B: Faulkes Telescope North and South Optical Afterglow
- GRB 091208A, RIMOTS optical upper limits
- GRB 091208B: MITSuME Akeno Optical Observation
- GRB 091208B: Enhanced Swift-XRT position
- GRB 091208B: MITSuME Okayama Optical Observation
- GRB 091208B, RIMOTS optical upper limits
- GRB 091208B: Swift detection of a burst with an optical afterglow
- GRB 091208B: BOOTES-3 optical afterglow
- GRB 091208: ROTSE-III Optical Limits
- GRB 091208: Swift detection of a burst
- Short X-ray Transient, RIMOTS optical upper limits
- A small revision to the GRB-naming convention
- GRB 091123: Suzaku WAM observation of the prompt emission
- GRB 091127: Skynet/PROMPT Observations of Possible Host Galaxy
- GRB 091127: GAO 150cm telescope Optical Observation
- GRB 091202: GTC & CAHA optical/nIR afterglow candidate
- GRB 091109A: GROND confirmation of redshift z = 3.5
- GRB091127: Continuing Swift/UVOT Observations
- GRB 091127, SMARTS optical/IR afterglow observations
- GRB091202: Swift-XRT refined analysis
- GRB 091202: Swift/UVOT Upper Limits
- GRB 091202: Liverpool Telescope observations
- GRB 091202: Optical and NIR observations
- GRB 091202 - UVOT-enhanced XRT position
- GRB 091127: Zadko Telescope Observations
- GRB 091126A: Suzaku WAM observation of the prompt emission
- GRB 091202: TAROT Calern observatory optical observations
- GRB 091202: Liverpool Telescope Observations
- GRB 091202: a long GRB detected by INTEGRAL
- GRB 091127: redshift confirmation with X-shooter
- GRB 091117: Chandra Observations
- GRB 091020: MASTER-Net optical polarization observations
- GRB 091127: Skynet/PROMPT Continued Observations of Fading
- Short X-ray Transient Detection by MAXI/GSC
- Konus-Wind observation of very long GRB 091123
- GRB 091130A: Xinglong TNT upper limit
- GRB 091123: Fermi GBM detection of a very long burst
- GRB 091126B: Fermi GBM detection
- GRB 091127: Suzaku WAM observation of the prompt emission
- GRB 091126: Fermi GBM detection
- GRB 091130B: Swift-XRT team refined analysis
- GRB 091130B: Swift-BAT refined analysis
- GRB 091130B: Swift/UVOT Upper Limits
- GRB 091127: Skynet/PROMPT Observations of Fading
- GRB 091130B: Enhanced Swift-XRT position
- Swift trigger 377436 (possible GRB 091130A) is not a burst
- GRB 091130B: MASTER observations
- GRB 091130B: SDSS galaxy at XRT location
- GRB 091130B: Swift detection of a burst
- GRB 091130: MASTER observations
- GRB 091130: Swift detection of a possible burst
- GRB 091127: Radio observations
- GRB 091128: Fermi GBM detection
- Konus-Wind observation of GRB 091127
- GRB 091127: TAROT La Silla observatory optical observations
- GRB 091127: optical observations
- GRB 091127: LABOCA/APEX submm observations
- GRB 091127: Further NOT optical observations
- GRB 091127: Fermi GBM detection
- GRB 091127: MASTER early optical transient polarimetry
- GRB 091127: Gemini-N redshift
- GRB 091127: Swift-XRT afterglow detection and analysis
- GRB 091127: TAROT La Silla observatory optical decay
- GRB 091127: Swift/UVOT observations
- GRB 091127: CAHA 1.23m I-band observations
- GRB 091127: Swift-BAT refined analysis
- GRB 091127: NOT observations
- GRB 091127 : GROND observations
- GRB 091127: REM NIR afterglow detection
- GRB 091127: Swift/UVOT Detection of an Optical Afterglow
- GRB 091127: Liverpool Telescope afterglow candidate
- GRB 091127: Swift detection of a burst
- IPN Triangulation of GRB091120
- Konus-Wind observation of GRB 091120
- GRB 091120: MAXI GSC detection
- GRB 091120: Fermi GBM observation
- GRB 091117A: Suzaku WAM observation of the prompt emission
- GRB 091117: TNG optical observations
- GRB 091117A: Swift/UVOT followup observations
- GRB 091117: 2nd epoch of Magellan optical observations
- GRB 091117: VLA radio observations
- GRB 091117: Swift-XRT observations
- GRB 091117 BAT refined analysis
- GRB 091117: Evidence for Variability of XRT Source #1
- GRB091117: Gemini South Observations
- GRB 091117: Swift XRT refined analysis
- GRB 091117: Gemini-North spectroscopy of DSS galaxy
- Konus-Wind observations of GRB 091117A
- GRB 091117: Magellan optical observations
- GRB 091117: XRT source coincident with a DSS galaxy