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 150126A: Fermi GBM Detection
- GRB 150126A: MAXI/GSC afterglow candidate detection
- Konus-Wind observation of GRB 150123A
- GRB 150120A: possible AMI 15 GHz detection
- GRB 150123A: Swift/UVOT observations
- GRB 150123A: Swift-XRT observations
- GRB 150120B: Mondy optical observations
- GRB 150123A Tiled Swift observations
- GRB 150123A: MAXI/GSC detection
- Konus-Wind observation of GRB 150118B
- GRB 150120B: RATIR Optical and NIR Observations
- IPN Triangulation of GRB 150118B (long/intense)
- GRB 150120A: ISON-NM early optical limit
- GRB 150120B: FTN early optical light curve
- GRB150120B: Xinglong TNT optical observation
- GRB 150120B: Swift/UVOT Upper Limits
- GRB 150120B, Optical observations
- GRB 150120B: GROND Afterglow Detection
- GRB 150120B: Additional P60 observations
- GRB 150120A: Swift-XRT refined Analysis
- GRB 150101B: Confirmation of a fading optical counterpart
- GRB 150120A: KAIT Optical Upper Limit
- GRB 150120B: MITSuME Okayama upper limits
- GRB 150120B: Swift-BAT refined analysis
- GRB 150120A: Swift-BAT refined analysis
- GRB 150118C: Fermi GBM Detection
- Konus-Wind observation of GRB 150118C
- GRB 150101B/Swift J123205.1-105602: TNG NIR follow-up
- GRB 150120B: Swift-XRT refined Analysis
- IPN triangulation of GRB 150118C (short/hard)
- GRB 150120A: Swift/UVOT Upper Limits
- GRB 150110B: AMI 15 GHz detection of possible radio counterpart
- GRB 150101B/Swift J123205.1-105602, deep VLT observations
- GRB 150120B: Enhanced Swift-XRT position
- GRB 150120A: Fermi GBM observation
- GRB 150101B/Swift J123205.1-105602: XMM-Newton observation
- GRB 150120A: Enhanced Swift-XRT position
- GRB 150120B: FTN optical afterglow confirmation
- GRB 150120B: P60 optical afterglow
- GRB 150120B: Swift detection of a burst
- GRB 150120A: Gemini-North optical imaging
- GRB 150120A: P60 optical observations
- GRB 150120A: Prompt enhanced Swift-XRT position
- GRB 150120A: Swift detection of a possibly-short burst
- GRB 150101B/Swift J123205.1-105602: continued WSRT radio and VLT optical observations
- GRB 150118B: Fermi GBM Detection
- GRB 150118B: Fermi-LAT detection
- Trigger 626581: Swift detection of GRO J1008-57
- GRB 150110B: Khureltogot optical upper limit
- The Swift Detection of a Large Flare from the RS CVn Binary SZ Psc
- Swift detection of the variable star SZ Psc
- GRB 150110C: Swift/UVOT Upper Limits
- GRB 150110C: Swift-XRT observations
- GRB 150110B: Swift-BAT refined analysis
- GRB 150110A: MASTER inspection
- GRB 150110C Tiled Swift observations
- GRB 150110B: Swift-XRT refined Analysis
- GRB 150110B: Swift/UVOT Upper Limits
- GRB 150110B: Fermi GBM Detection
- GRB 150110B: Enhanced Swift-XRT position
- GRB 150110C: MAXI/GSC detection
- GRB 150110A: Fermi GBM Detection
- GRB 150110B: Swift detection of a burst
- GRB 150110A: MAXI/GSC detection
- GRB 150101B/Swift J123205.1-105602: Chandra observations
- GRB 150101B / Swift J123205.1-105602: 9.8 GHz VLA observations
- Fermi GBM trigger 150108121 is not a GRB
- GRB 150101B/Swift J123205.1-105602: WSRT radio observation
- GRB 150101B / Swift J123205.1-105602: X-ray counterpart is likely an AGN
- Radio upper limit on the GRB 141121A with the GMRT
- Fermi GBM trigger 150106207 is not a GRB
- GRB 150105A: Fermi GBM detection
- GRB 150101B/Swift J123205.1-105602: VLT observations and redshift
- Swift detection of 4U 1700+24 (= V* V934 Her)
- GRB 150103A: MASTER optical observations
- GRB 150101B: potential host galaxy redshift by GTC
- GRB 150103A: Swift-XRT refined Analysis
- GRB 150101B: Fermi GBM detection
- GRB 150103A: Swift/UVOT Upper Limits
- GRB 150103A: Swift-BAT refined analysis
- GRB 150103A: Zadko observatory - Gingin optical observations
- GRB 150103A: Enhanced Swift-XRT position
- Swift J123205.1-105602: Magellan candidate afterglow
- GRB 150103A: Prompt enhanced Swift-XRT position
- GRB 150103A: Swift detection of a burst
- Swift J123205.1-105602: XRT and UVOT observations of soft short burst source
- Short burst found in ground analysis of Swift-BAT data
- GRB 150101A Swift-BAT refined analysis of the short hard burst
- GRB 150101A: Fermi GBM detection
- GRB 150101A: Swift-XRT refined Analysis
- GRB 150101A: Swift/UVOT Upper Limits
- GRB 150101A: Enhanced Swift-XRT position
- GRB 150101A: Swift detection of a short burst
- Konus-Wind observation of GRB 141229A
- GRB 141229A: Deep MASTER inspection
- Swift-XRT and UVOT follow-up of iPTF14jko (GRB 141230A)
- GRB 141230A: Fermi GBM detection
- GRB 141229A Swift-BAT observations
- GRB 141230A: Nanshan optical obsrvations
- GRB 141230A: iPTF Optical Observations and Candidate Afterglow iPTF14jko