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 060428B: MDM Observations
- GRB 060428A: PROMPT Observations
- GRB 060427B: MASTER optical observations
- GRB060428B: Swift XRT Team refined analysis
- GRB 060427B: IPN localization of a short hard burst
- GRB 060428B: Refined analysis of the Swift-BAT burst
- GRB 060428B: Xinglong I-band limit
- GRB 060428B: KAIT observations
- GRB060425:MASTER optical limit
- GRB 051117A: Bright host galaxy not confirmed
- GRB060428A: Swift/UVOT observations.
- GRB060428B, optical observation
- GRB 060428A: Refined analysis of the Swift-BAT burst
- GRB 060428b : Kiso R-band limit
- GRB060427:MASTER optical limit
- GRB 060428b: Optical afterglow candidate
- GRB060428A: Swift XRT Team refined analysis
- GRB 060428B: Swift detection of a burst
- GRB 060427: NIR observations
- GRB060427: Xinglong optical Observations
- GRB 060428: Swift detection of a burst
- GRB 060427: NOT observations
- GRB 060427: Swift/UVOT upper limits.
- GRB 060427: Refined analysis of the Swift-BAT burst
- GRB060427: Swift XRT Team refined analysis
- GRB060418: Swift XRT Team Further Refined Analysis
- GRB060425:MASTER survey observations
- GRB 060427, optical observation
- GRB 060427: Swift detection of a burst
- GRB 060425: IPN localization and KW spectrum of a short, hard burst
- An interactive program for GRB pseudo-redshift computations
- GRB060424: optical afterglow detection
- GRB060418: Further Analysis of MIKE Spectroscopy
- GRB 060424: Refined analysis of the Swift-BAT burst
- GRB 060424: Swift detection of a burst
- GRB 060421: TTT Observations
- OT 060420: Likely Not a New Cosmic Transient
- No OT 060420 in MASCOT images
- Swift-BAT detection of Mrk 421
- OT 060420: CONCAM detection of a candidate new magnitude 5 optical
- GRB060421: Swift/UVOT observations
- GRB 060421: Swift-BAT Refined Analysis
- GRB 060421: Swift-XRT refined analysis
- GRB 060418: prediction of t_break
- GRB060418: optical observations
- Konus-Wind observation of GRB 060418
- GRB(?)060421:MASTER optical limit
- GRB(?)060421 : XRT position
- Possible GRB060421: BART limits
- GRB(?) 060421: Swift detection of a burst
- Erratum of GCN 4983 for GRB 060418 IR follow-up
- GRB 060418 : IR afterglow observations
- GRB 060418 : Lulin Optical follow-up
- GRB 060418: JHKs PAIRITEL Observations of Afterglow
- GRB 060418: Radio Observations
- GRB060418, BVRcIc field calibration
- GRB060418: Swift/UVOT Observations
- GRB060418: Optical Observations
- GRB 060418: FRAM early afterglow observation
- GRB 060418: Refined Analysis of the Swift-BAT burst
- VLT/UVES observations of GRB060418
- GRB060418: Swift XRT Team Refined Analysis
- GRB 060418, SMARTS continuing afterglow observations
- GRB 060418: PROMPT Detections
- GRB 060418, SMARTS optical/IR afterglow observations
- GRB060418: Magellan/MIKE Spectroscopic Redshift
- GRB060418 : LT optical afterglow observation
- GRB 060418: REM candidate afterglow
- GRB 060418: Swift detection of a burst with bright x-ray and optical afterglow
- SGR 1900+14: Refined analysis of the Swift-BAT outburst
- GRB060413: Swift/UVOT upper limits
- GRB 060413: REM NIR Observations
- SGR 1900+14: Swift detection of an outburst
- GRB 060413: Refined analysis of the Swift-BAT burst
- GRB 060413: Watcher UBVR observations
- GRB 060413: XRT refined analysis
- GRB 060413: No Optical Afterglow in Swift/UVOT TDRSS Data
- GRB 060413: Swift detection of a burst
- GRB060403: optical observations
- GRB 060403 Optical observations
- GRB 060403: MITSuME optical observation
- GRB060403: Optical Limit
- GRB060403: XRT refined analysis
- GRB 060403: Swift/UVOT upper limits
- HETE Triggers H4043 and H4044 Not Due to New Cosmic Source
- SGR 1900+14: BAT observations
- GRB 060403: Refined analysis of the Swift-BAT burst
- GRB060403: Swift XRT refined position
- Konus-Wind observation of the recent SGR 1900+14 activity. Will
- GRB 060403: Swift detection of a burst
- HETE trigger H4044: RTT150 optical observations
- GRB060331: Swift/UVOT upper limits
- H4044, a Repeat Outburst From The Source of H4043 (="GRB060331")
- Swift XRT observations of the HETE transient H4043
- HETE Trigger 4043: ROTSE-III Optical Limits
- Correction to Circular 4938, =H4043, an unusual high energy transient observed by HETE
- H4043, an unusual high-energy transient observed by HETE
- GRB 060322: LNA optical limit
- SGR 1900+14: bright burst detected by Konus-Wind on March 28
- INTEGRAL and XMM ToO observations of SGR1900+14