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 050219b: CORRECTION: Swift XRT Position
- GRB 050219b: Swift XRT Position
- GRB 050219a, optical observations
- GRB 050219a: Refined XRT position
- GRB050219a: No Swift UVOT Detection of Afterglow Emission
- GRB 050219: Swift-BAT detection of a burst
- GRB050215b: Swift UVOT Detection of Afterglow Emission
- GRB 050219: Prompt X-ray position
- GRB 050215B: Radio Observations
- GRB 050215b: XRT confirmation of IR afterglow candidate
- GRB050215b: P60 Optical Observations
- GRB 050215b: Swift XRT Source Variability
- GRB 050215B: candidate afterglow
- GRB 050215b : Lulin follow-up observation
- GRB 050215b, BOOTES-2 simultaneous optical observations
- GRB 050215B: UKIRT K-band imaging
- GRB 050215b: Swift XRT Observations
- GRB050215b: No Swift UVOT Detection of Afterglow Emission
- GRB050215a: No Swift UVOT Detection of Afterglow Emission
- Swift-BAT detects two bursts: GRB050215a and GRB050215b
- GRB 050215b, BOOTES-1B optical limit
- GRB050215B: ROTSE-III optical observations
- GRB050215A: ROTSE-III Optical Observations
- GRB050209: TAROT optical observations
- GRB 050209(=U11568): Duration and spectrum
- short/hard GRB 050202, optical observations
- GRB050209: REM optical observations
- GRB 050209 I-band observation
- GRB 050209 Optical observations
- GRB050209: P60 Optical Observations
- GRB050209 (=U11568): A Long GRB Detected by HETE
- GRB 050209: Optical observation
- GRB 050128: Radio observations
- Further analysis of the short Swift-BAT GRB 050202
- GRB 050202: Second epoch radio observations
- GRB 050129: Optical observations
- GRB050202: Radio Observations
- GRB 050202: Optical observations with LCO40
- GRB 050202: Short burst detected by Swift-BAT
- GRB 050128 Optical observation with REM
- GRB 050129: a weak long GRB detected with INTEGRAL
- SGR1806-20: Swift-BAT detection of a large normal burst
- GRB050128: Faulkes Telescope South observations
- GRB 050124: Radio Observations
- GRB 050128: near-infrared observations with REM
- GRB050128,optical observations
- GRB 050126: A NIR afterglow candidate in the revised XRT error circle
- GRB050126: Updated Swift XRT Position
- SGR 1806-20: GMRT results at 240 MHz band.
- SGR 1806-20: low frequency GMRT results of 2005 Jan 16.
- GRB 050126: Radio Observations
- GRB050128 Swift-BAT observations
- GRB 050128: Swift XRT prompt afterglow position
- HETE #3667: P60 Observations
- GRB 050124: K-band afterglow observations
- GRB050126: MASTER optical limit for KECK OT
- GRB050126: Burst Parameters Measured by BAT
- GRB050126: MASTER optical observations
- GRB 050126: Detection of NIR afterglow with Keck/NIRC
- GRB 050126: Prompt XRT detection and localization
- GRB 050124: NIR afterglow confirmed with Keck/NIRC
- GRB050124: No Swift UVOT Detection of Afterglow Emission
- GRB 050124, SMARTS optical/IR observations
- GRB 050117a: Radio Observations
- GRB 050124 I-band observation
- GRB 050124: NIR Candidates from Keck/NIRC
- GRB050124,optical observation
- GRB 050124 : Lulin R-band follow-up observation
- GRB050124: Updated Swift XRT Position and Fluxes
- GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
- GRB050124: Refined BAT position, spectral and fluence information
- GRB050124: Swift-BAT position of a double-peaked burst
- GRB 050123 : I-band follow-up observation
- GRB050123: optical limit 1.8h before GRB
- GRB050123,optical observation
- GRB 050123: KAIT observations
- GRB050123: P60 Observations
- GRB 050123(=H3666): A GRB Localized in Real Time by HETE
- CFHTLS optical transient unlikely to be a GRB
- Unusual optical transient (GRB ???)
- GRB050117a: Radio Observations
- GRB050117a: Refined analysis
- GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
- GRB050117: Palomar WIRC Ks-band observations
- GRB050117b: Swift-BAT detection of a weak burst
- GRB050117: optical observation
- GRB 050117, I-band observations
- GRB 050117: Optical observation
- GRB050117: Refined XRT position
- GRB050117: MASTER optical observations
- MASTER:GRB050117 SWIFT
- GRB050117: Swift-BAT detection of a long multi-peaked burst
- GRB050117: Swift XRT Position
- SGR 1806-20: RXTE/PCA pulse frequency during flare
- Triangulation of Short Hard GRB050112 (large error box)
- SGR 1806-20: Further VLA Observations
- SGR 1806-20: Further low frequency GMRT results
- SGR 1806-20: Further VLA Observations
- SGR1806-20: Swift-BAT observations of two additional bursts
- SGR1806: Optical Transient Candidates in SOHO/LASCO Images