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 060313, SMARTS optical/IR observations
- GRB060313: optical and near infrared observations with REM
- GRB 060313: Swift-BAT detection of a bright short hard burst
- GRB060218: SARA Observations of SN2006aj
- GRB060312: Swift UVOT observation
- GRB 060312: Refined analysis of the Swift-BAT burst
- GRB 060218/SN 2006aj, high resolution spectra
- GRB 060312: Swift XRT team refined analysis
- GRB060306: APO Ks-band Imaging Observations
- GRB 060312: ROTSE-III Optical Limits
- GRB 060312: Swift detection of a burst
- IBAS Alert n. 3218 : not a real GRB
- GRB 060306: SOAR Ks Observations
- Bright short hard GRB 060303: IPN localization and Konus spectrum
- GRB060219: Liverpool Telescope observations
- GRB 060306: MAGNUM observations
- GRB060218: analysis of the XMM-Newton observation
- Swift/UVOT observations of GRB060306
- GRB 060306: Swift-BAT refined analysis
- GRB 060306: Swift-XRT team refined analysis
- GRB 060306: PROMPT Observations
- GRB 060306: Swift detection of a bright burst
- GRB 060218: RTT150 optical observations
- GRB060218: Ep,i - Eiso correlation
- GRB060218: R-band CCD photmetry
- GRB060223b: optical limit
- GRB060218/SN 2006aj: optical observation in V
- GRB060218/SN 2006aj: optical observation
- GRB 060121: HST observations
- GRB 060218 : GMRT observation [Correction and Improvement]
- GRB 060223b: Swift/UVOT Upper Limits
- GRB 060218/SN 2006aj: K-380 optical observations
- GRB 060218/SN 2006aj, SMARTS optical/IR observations
- GRB200618: optical polarimetry and photometry
- GRB 060223B: Swift XRT possible afterglow
- GRB 060218/SN 2006aj: ABT observations
- GRB 060218/SN 2006aj: REM optical and near-infrared observations
- GRB 060218 : Radio upper limits from GMRT
- GRB 060218/SN 2006aj: WIRO optical observations
- GRB 060218/SN 2006aj: RBO optical observations
- GRB 060204B: GETS early limit
- GRB 060218: Refined analysis of the radio afterglow
- GRB 060223A:Xinglong optical limits
- GRB 060223B: ART optical limits
- GRB 060223B: Swift-BAT refined analysis
- GRB 060223a: Swift/UVOT refined analysis
- GRB 060223: Swift XRT Team preliminary analysis
- GRB 060218/SN 2006aj: Swift-BAT fluence and peak flux
- GRB 060223B: Swift detection of a bright burst
- GRB 060223: Swift-BAT refined analysis
- GRB 060218: rebrightening
- Correction to GCN 4816 on GRB060218
- GRB 060218/SN 2006aj: optical observations
- GRB060218: Optical brightening in V and R
- GRB 060223: Keck redshift
- GRB 060223: Swift/UVOT Confirmation of Optical Afterglow
- GRB 060223: Swift detection of a burst
- Spectral properties of GRB060218/SN2006aj
- GRB 060219: Swift-BAT refined analysis
- GRB 060218: rebrightening
- GRB 060218: emergence of the underlying SN spectrum
- GRB 060218: Decline in r-band flux
- GRB 060218: spectroscopic observations
- GRB 060218: Further refined analysis of the Swift-BAT burst
- GRB 060218: Likely an underluminous GRB
- GRB060218: Optical Spectroscopy of GRB-SN
- GRB060218: VLT spectroscopy
- GRB 060218: Optical Observations at Xinglong Obs.
- GRB 060219: SDSS galaxy inside XRT error circle
- GRB060218: UV Detection and Light Curves
- GRB060219: SARA Observations
- GRB 060219: Swift/UVOT Upper Limits
- GRB 060219: Swift-XRT Team refined analysis
- GRB 051221B: Swift-XRT Team Refined Analysis
- GRB 060219: Partial refined analysis of the Swift-BAT burst
- GRB060218: Radio Afterglow Discovery
- GRB 060219: Swift-XRT position typo correction
- GRB 060218: MDM Redshift
- GRB 060219: Swift-XRT position
- GRB 060218: optical/nIR observations at La Palma
- GRB060219: SDSS pre-burst observations
- GRB 060219: Swift-BAT detection of a weak burst
- Oddball GRB 060218, transient or GRB?
- GRB060218: Swift/XRT Team preliminary analysis of the possible burst
- Brightening of the Optical Counterpart of the Possible GRB 060218
- GRB 060218: MDM Observations
- GRB 060218: Pre-burst detection of a possible host galaxy
- GRB 060218A: ROTSE-III Possible Optical Flare
- GRB060218: Swift/XRT refined position of a possible burst
- Preliminary refined analysis of the Swift-BAT trigger 191157
- Further UVOT Observations of the Candidate Optical Afterglow for GRB 060218
- GRB 060211B: Swift/UVOT Upper Limits
- GRB060218 : SDSS pre-burst observations
- GRB 060218: Swift XRT Position
- GRB 060218: Swift-BAT detection of a possible burst
- GRB 060213: optical afterglow not confirmed
- Swift UVOT observations of GRB060213
- GRB 060211B: Skynet Observations
- GRB 060213: optical afterglow candidate
- GRB060213: Swift XRT observations and possible afterglow candidate