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 051221A: Chandra Afterglow Position
- GRB 051221A: Refined spectral and temporal analysis of the Swift-BAT short hard burst
- GRB 051221B: ROTSE-III Optical Limits
- GRB 051221B: TAROT optical limits
- GRB 051221A: WSRT Radio Observations
- GRB 051221: Redshift from Gemini
- GRB 051221: Continued fading of optical afterglow
- GRB 051221B: Refined analysis of the Swift-BAT burst
- Possible GRB 051221B: MDM Optical Detection
- GRB 051221A: RAPTOR Fading Counterpart Constraint
- GRB 051221B: BOOTES optical observations.
- Possible GRB 051221B: Swift XRT position
- GRB 051211A: Evidence This Is a Short Burst from Analysis of Spectral
- Swift-BAT detection of a possible burst
- GRB 051221: Discovery of fading optical afterglow
- GRB 051221: Swift XRT refined analysis
- GRB 051221: Swift/UVOT upper limits
- GRB 051221: Possible nearby cluster
- GRB 051221: No variability in Gemini data
- GRB 051221: Correction to GCN #4368
- GRB 051221: Gemini observations
- GRB 051221: Improved astrometry of the IR counterpart
- GRB051221: K-band source
- GRB 051221: XRT position
- GRB 051221: Refined analysis of the Swift-BAT short hard burst
- GRB 051221: IR Observations at GRB+1hr
- GRB 051221: Swift detection of a bright short burst
- Refined analysis of the SWIFT J1626.6-5156
- Swift-BAT discovery of hard x-ray transient SWIFT J1626.6-5156
- Refined analysis of the Swift-BAT detection of the RS CVn star II Peg
- GRB051211A (=H3979): Refined Analysis
- GRB 051211B: optical afterglow
- Swift detection of an RS CVn flare star
- GRB051211A: possible optical candidate
- Swift Trigger 172767 is not a GRB
- GRB 051215: near-infrared observations
- GRB051215 - SDSS pre-burst observations
- GRB 051215: Swift detection of a possible burst
- GRB 051215: A short GRB in a cluster?
- GRB051211B: Probable radio afterglow
- GRB051105: optical observations
- GRB 051213: Swift-BAT refined analysis
- GRB051211B: XRT refined analysis
- GRB 051211B, optical observation
- GRB 051213: Swift-BAT detection of a burst
- GRB 051211a: RTT150 optical observations
- GRB051211B, RBO optical observations
- GRB 051211A: Swift/UVOT upper limits
- GRB 051211B: Swift/UVOT upper limits - correction
- GRB 051211B: Swift/UVOT upper limits
- GRB 051211A,optical observation
- GRB 051211B: Swift XRT confirmation of the afterglow
- GRB051211B: Liverpool Telescope observation
- GRB 051211b: RTT150 optical observations
- GRB051211b: P60 Observations
- GRB 051211A and GRB051211B: BOOTES simultaneous observations
- GRB 051211B: Swift XRT Observations
- GRB 051210: Swift/UVOT upper limits
- GRB 051210: Magellan Imaging
- GRB 051211: TAROT optical limits
- GRB 051211B: a possible optical detection by TAROT
- GRB 051211B: a long GRB detected by INTEGRAL
- GRB 051211: Swift XRT upper limit
- GRB 051211:IAC80 optical observations
- HETE SXC localization of GRB 051211 (=H3979)
- GRB 051210: Optical imaging from Las Campanas
- GRB 051210: SALT detection limit
- GRB 051210: BAT further refined analysis of the short burst
- GRB 051210: Swift XRT refined analysis
- GRB 051210: FRAM early limit
- GRB 051210: Swift-BAT refined analysis of a short burst
- GRB051210: Swift UVOT Observation
- GRB 051210: A short GRB in a cluster?
- GRB 051210: Swift detection of a burst
- IPN observations of SGR1806-20
- Swift XRT positions
- An extraordinary long burst on December 3 from SGR1806-20
- IBAS Alert 2706 : not a real GRB
- Possible resuming of the SGR 1806-20 activity
- Swift UVOT Calibration Documentation
- GRB051117B: optical observation
- GRB051111: optical observaion
- Swift-BAT trigger 165579 is not a GRB
- GRB 051127: Swift-BAT detection of a possible burst
- GRB051117B: Swift XRT refined analysis
- GRB051117b: No Swift/UVOT Detection
- GRB051111: Rc optical observations: correction
- GRB 051117A: Swift/UVOT Detection of an Afterglow: Correction
- GRB 051117A: Swift/UVOT Detection of an Afterglow
- GRB051111: Suzaku WAM observation of the prompt emission
- GRB051111: Rc optical observations
- GRB051008: Suzaku WAM observation of the prompt emission
- GRB 051109B: GAO 150cm telescope Optical limit
- GRB 051109A : GAO 150cm telescope Rc-band detection
- GRB 051021 Optical Observations
- GRB 051117B: MARGE Optical Limits
- GRB 051117A and B: Radio Observations
- GRB 051117B: R and I observations of possible host galaxy
- GRB 051117b: NIR observations
- GRB 051117A: Refined analysis of the Swift-BAT burst