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 060510B: Swift detection of a burst
- GRB 060510: Swift detection of a burst with optical transient
- GRB060507: optical afterglow detection
- GRB060502B: improvement in the XRT afterglow position
- GRB 060507: BART limit
- GRB 060507: Final Refined analysis of the Swift-BAT burst
- GRB 060507: Swift-BAT Refined Analysis
- GRB 060505: PROMPT Observations
- GRB 060507: Swift/UVOT Upper Limits
- GRB 060507: Swift XRT Team Refined Analysis
- GRB 060507: MDM Optical Upper Limit
- GRB060507: Swift XRT position
- GRB 060507: Swift detection of a burst
- GRB 060429: Suzaku WAM observation
- GRB060505: Swift/UVOT Observations
- GRB 060505: Swift XRT Team Refined Analysis
- GRB060425: new MASTER survey method
- GRB 060306: Further Analysis of SOAR and APO NIR Observations
- GRB 060505: Swift XRT afterglow canditate position
- GRB 060502b: Second epoch Gemini observations
- GRB 060505: Swift-BAT detection of a weak burst
- GRB 060428B: spectroscopy
- GRB 060502B: optical observations
- GRB 060502B: AROMA refined photometric calibration
- GRB 060502B MDM Follow-up Observation
- GRB 060502b: Gemini imaging and spectroscopy
- GRB060502A, optical observation
- GRB 060502B: Swift/UVOT upper limits
- GRB 060502A: Swift/UVOT source detection
- GRB 060429: Refined IPN error box and Konus-Wind spectrum
- GRB 060502B: MDM Optical Observation
- GRB 060502B: AROMA optical observations
- GRB 060502B: Refined analysis of the Swift-BAT short burst
- GRB060502B: Swift XRT Team refined analysis
- Short GRB 060502B: Tautenburg Observation
- GRB 060427B Milagro GeV/TeV Observations
- GRB 060502A: TTT Observations
- GRB060502B: correction to XRT position
- GRB 060501: P60 Observations and Candidate Retraction
- GRB 060502B: Xinglong optical observation
- GRB 060502B: MASTER optical observations
- GRB 060502B: Swift detection of a short burst
- GRB060502: Swift-XRT refined analysis
- GRB 060502: Swift-BAT refined analysis
- GRB060502: Gemini spectroscopy
- GRB 060502: APO Spectroscopic Observations
- GRB060501: Swift UVOT followup observations
- GRB060502: Super-LOTIS Observations
- GRB 060502: P60 Afterglow Confirmation
- GRB 060502: Swift detection of a burst with an optical counterpart
- GRB 060501: MDM Observations
- GRB060501: Super-LOTIS observations
- GRB060501: P60 imaging and afterglow candidate
- GRB 060501: Refined analysis of the Swift-BAT burst
- GRB060501: Swift XRT position
- GRB 060501: ROTSE-III Optical Limits
- GRB 060501: Swift detection of a burst
- IPN triangulation of GRB060429 (short/hard)
- Konus-Wind observation of GRB 060427B
- GRB060428B - SDSS Pre-Burst Observations
- GRB060428B: optical observation
- GRB060428B: possible detection of an optical counterpart by Swift/UVOT.
- 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