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"2744 results found.
- GRB 051021: Optical observations and candidate afterglow
- Swift-BAT triggered on a posible CR Shower or possible GRB
- Photometric calibration of Swift/UVOT and Re-analysis of Swift/UVOT GRB 050922C data
- GRB051006: optical observations
- Swift-BAT Trigger 159578 is a possible burst
- GRB050805A: Rc optical observations
- GRB 051008 - a low redshift low-luminosity burst?
- GRB051011: bright nebulae near error box
- GRB 051008: Swift UVOT Candidate
- GRB 050906, summary of radio observations
- GRB 051001: ROTSE-III Optical Limits
- GRB/SGR 050925: IR Observations
- GRB050925: Swift-BAT detection of a short burst
- GRB 050922C: ROTSE-III Detection of Possible Counterpart
- GRB050922B: Swift-BAT detection of a weak long burst
- Possible GRB 050922 detected by INTEGRAL
- GRB050918: Possible Swift/XRT detected afterglow
- Swift trigger 155764: bad XRT centroid
- GRB050911: Swift-XRT position
- GRB 050911: z~0.16 cluster in the field
- GRB 050906: Possible X-ray Counterpart
- GRB 050908: Swift detection of a burst
- GRB 050906: Swift-BAT refined analysis
- GRB050906: P60 Observations
- GRB 050904: Did SWIFT/XRT see the prompt GRB emission ?
- GRB 050906: Bright galaxy in BAT error box
- GRB 050906: Swift/BAT Detection of a possible burst
- GRB 050904: Possible High-Redshift GRB
- GRB050904: Swift-BAT detection of a probable burst
- Retraction of Swift-BAT trigger #153355
- GRB 050827: P200 NIR Observations
- GRB 050827: XRT possible afterglow detection
- GRB 050826: BAT refined analysis
- Possible GRB050825:MASTER optical observations
- GRB 050824: XRT refined analysis and possible afterglow detection
- GRB 050820a - corrections to GCN 3846
- GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
- GRB050817: Negative Optical Observations
- GRB050817: Swift-BAT Detection of a burst
- GRB050815: Swift-BAT detection of a burst
- GRB 050813: Non-fading of afterglow candidate
- GRB 050813: Possible Short Swift-BAT GRB
- GRB 050730, optical observation
- Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
- GRB 050803: RTT150 optical observations
- GRB050803: CrAO optical observations, possible OT candidate
- GRB 050801: ROTSE-III Early Afterglow Break
- GRB 050801: ROTSE-III Detection of Possible Counterpart
- GRB050730: Swift-BAT detection of a weak burst
- Swift-BAT trigger 147918 is not a real GRB
- GRB050726: Swift-BAT detection of a weak burst
- GRB 050724: J-band observations
- GRB 050724: GMOS Imaging and Spectroscopy
- GRB 050724: Optical limit
- GRB050724: Refined analysis of the Swift-BAT possible short burst
- GRB 050724: possible host galaxy in DSS
- Swift-BAT detection of a possible GRB
- GRB050713: possible I-band afterglow
- GRB050709: A Possible Short-Hard GRB Localized by HETE
- H11603: An X-ray flare from V4641 Sgr, or a possible XRF
- H3804: A Possible New XRB Detected by HETE
- GRB 050607: MDM Observation
- GRB050528: updated Liverpool Telescope limits
- GRB050528: BOOTES optical candidate (retraction)
- Possible GRB050528: no candidate from Liverpool Telescope
- Swift-BAT detection of possible GRB 050528
- GRB 050509b: refined XRT/Chandra afterglow position analysis
- GRB 050525A: ROTSE-III Detection of Possible Counterpart
- GRB 050509b: Further Analysis of Keck LRIS Images
- GRB 050509b: Possible Optical Counterpart
- Keck/DEIMOS Spectrum of Possible Host Galaxy for GRB050509b
- Swift Detection of GRB050509b: A short duration burst
- GRB050505: Infrared observations
- Renewal of SGR 1806-20 activity
- GRB 050502: ROTSE-III Detection of Possible Counterpart
- Swift/BAT possible detection of a weak burst GRB050430
- GRB 050421: early Swift XRT analysis results
- GRB050418: Null Optical Observations
- GRB 050408: refined XRT analysis, no jet break seen yet
- Swift-BAT Detection of GRB 050412: A Bright, Long Burst
- GRB 050408: Swift XRT measurement of possible jet break
- GRB 050406 BAT refined analysis
- Swift-BAT detection of GRB 050406
- GRB050401: Radio observation at 610 MHz with GMRT
- GRB 050315: Variability Analysis of Swift BAT Time History
- GRB 050319: Detection of Possible Optical Counterpart
- GRB050316: MASTER optical observations
- GRB 050315: Swift-BAT further refined analysis
- Non-detection of GRB050315 in ATCA Radio Observations
- GRB 050306: optical afterglow
- Swift-BAT trigger 107873: No Swift XRT counterpart
- Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
- GRB 050306: REM optical-infrared observations
- GRB 050306: Possible X-ray Afterglow Position from the Swift
- GRB 050306: Swift-BAT detection of a long burst
- GRB050215b: Faulkes North and SDSS limits on UKIRT candidate
- GRB 050215b: Swift XRT Source Variability
- GRB 050126: A NIR afterglow candidate in the revised XRT error circle
- ATCA observations of SGR 1806-20
- The giant outburst from SGR 1806-20