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"27292 results found.
- GRB020321: BeppoSAX/NFI Observations
- GRB020321: a faint BeppoSAX detection
- GRB020317 (=H1959): Localization by HETE of a Low Fluence GRB
- GRB020317, optical observations
- GRB 011121: HST Observations reveal an intermediate-time multicolor
- XRF/GRB 011030: Detection of the Probable Host Galaxy
- GRB020305 (=H1939): Localization of a GRB by HETE
- IPN detection and localization of Cygnus X-1 flares
- GRB020127: Further VLA Observations of Possible Counterparts
- IPN detection of further SGR1900+14 activity
- IPN/HETE Detection of Bursts from SGR1900+14
- GRB020127: Palomar and VLA Observations of Possible Counterparts
- GRB020127: Comparison of Chandra Epochs and Identification of Possible Counterparts
- Type Ib/c SN2002ap (SN/GRB?)
- Type Ib/c SN2002ap (SN/GRB?) Radio Observations
- IPN detection of further activity from SGR1806-20
- GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE
- GRB020124(=H1896): Localization of a Long GRB by HETE
- GRB 011211: Detection of the Probable Host Galaxy
- GRB 011211: Evidence for an Optical Break
- GRB 011211: TNG Spectroscopic Observations
- GRB011130 (=XRF011130): Further analysis of Chandra Target of
- Sub-mm and Centimeter Detections of the Host Galaxy of GRB000418
- GRB 011130, K band observations
- Detection of the X-ray afterglow of GRB011121 by BeppoSAX
- GRB011130 (=XRF011130): Revised Localization of an X-ray
- GRB 011121: J-band observations
- GRB 011121: Detection of Bright IR Counterpart
- GRB 011030 I-band Observation
- The X-ray Flash 011030 ('GRB 011030')
- The Radio Afterglow from the X-ray Rich GRB 011030
- GRB 010921: HST Detection of the Afterglow and Host Galaxy
- GRB 000131: HST Detection of the Host Galaxy
- GRB 011030 K-band Observations
- GRB011019: ROTSE-III optical observations
- GRB010928(=H1770): Localization of a Long GRB by HETE
- BeppoSAX/GRBM detection of GRB 010801
- Dramatic Increase in the Rate of X-ray Bursts Reported by HETE
- BeppoSAX/GRBM detection of GRB010728
- SGR1900+14: High Fluence Burst Localized by HETE
- GRB010629: A Burst Localized by HETE
- SGR1900+14: Second Burst Localized by HETE
- SGR1900+14: A Burst Localized by HETE
- IPN detection of SGR1900+14
- SGR1806-20: A Second, Intense Burst Localized by HETE
- SGR1806-20: Localization by HETE
- GRB000301C: Late-time HST/STIS observation
- GRB010518: a faint BeppoSAX detection
- GRB000418: HST/STIS Second-epoch Observations
- SGR 1900+14: No evidence of extended X-ray emission
- SGR 1900+14: Detection of extended X-ray emission
- GRB 010222: High-Resolution Keck Spectroscopy
- GRB 010214, I-band data
- GRB 010222 Kyoto optical observation
- GRB010214 follow-up from Hanle
- GRB010222: Sub-millimeter detection
- GRB010222: Optical Observations
- GRB010222: possible optical counterpart
- GRB010220, Radio and Optical Observations
- GRB010213 Optical Observation
- GRB010213, Radio Observations
- GRB010214 Optical Observation
- IPN Status Report
- HETE Status
- GRB010126 opt. obs.
- GRB010126: CONCAM crude optical limits during GRB
- GRB010126 optical observations
- Optical Observations of GRB 001018 at Keck
- GRB 001212 Optical Observation
- Confirmation of IPN position for GRB001204
- WSRT 4.8 GHz observations of GRB001109
- IPN TRIANGULATION OF GRB001025B (SHORT/HARD)
- GRB001007: Optical observations
- GRB000926 - Amateur Optical Observations
- CONCAM null result on GRB001005
- CONCAM crude optical limits before and after GRB000926
- GRB 990510: Possible detection of a host galaxy
- GRB 000630: Detection of the Optical Afterglow
- GRB000620: BeppoSAX WFC and GRBM detection
- GRB000615, R-band photometry
- GRB980425, HST/STIS observations of the host galaxy
- GRB000604 optical non-detection
- GRB000604, optical observations
- GRB 000418: Detection of the Host Galaxy
- X-ray Afterglow of GRB 000529
- Possible GRB-related phenomenon
- GRB000424, optical observations
- GRB000418, Radio detection
- GRB000418, K'-band photometry
- GRB 000418, Optical Observation
- GRB000424, optical observations
- X-ray burst or X-ray rich GRB 000416 observed by BeppoSAX
- GRB 000301C: A Precise Redshift Determination
- GRB 000301C: HST/STIS CCD Imaging of the field
- GRB000301C - Host galaxy not detected in R (?)
- GRB000301C 250 GHz detection
- Correction to GCN 557 (GRB000214: BeppoSAX GRBM and WFC Detection)
- GRB000214: BeppoSAX GRBM and WFC Detection
- Optical observations of the Chandra X-ray source for GRB000210
- GRB000210: possible afterglow detection with BeppoSAX NFI