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"- Possible GRB050825:MASTER optical observations
- Swift-BAT trigger 152038 is definitely not a GRB
- GRB050824: CORRECTION to UVOT observing times
- Swift-BAT trigger 152038 is probably not a GRB
- GRB050824: Swift/UVOT detection of fading afterglow
- GRB050824: decay of the XRT light curve and updated X-ray spectrum
- GRB050824, I-band imaging
- GRB050824: Radio Observations
- GRB 050824: Spectroscopic redshift from the VLT
- GRB 050822: refined XRT analysis
- GRB 050824: XRT refined analysis and possible afterglow detection
- GRB 050824: BAT refined analysis of a soft weak burst
- GRB050824: MASTER:OT decay
- GRB050824: MASTER observation OT
- GRB050805a: MASTER optical candidat
- GRB 050824: ROTSE-III Optical Limits
- GRB050824: Swift-BAT detection of a burst
- GRB 050824 optical candidate
- GRB050820A: RTT150 optical observations
- GRB050820a: PROMPT RcIc Observations
- GRB050815: Maidanak optical observation
- XRF050509c: Radio upper limits from GMRT
- VLT/UVES spectroscopy of GRB050820
- GRB050822: Swift/UVOT upper limits
- GRB 050820A BAT observations of second, larger episode of emission
- GRB050813: Maidanak I-band observations
- GRB 050822: Swift-BAT refined analysis
- GRB050525, GRB050607, GRB050802 BVRcIc field photometry
- GRB050820B at FRAM
- GRB050820A: RTT150 optical observations
- GRB 050820a - corrections to GCN 3846
- Swift/UVOT UV Photometry of GRB 050820B
- GRB 050822: ROTSE-III Prompt Optical Limits
- GRB 050822: Swift detection of a long burst
- Correction to Eiso calculation in GCN 3835 on GRB 050820A
- GRB050820A: Radio Observation
- GRB050825a - very long GRB like GRB041219a? (Konus-Wind observation)
- GRB050820a BVRcIc field photometry
- GRB050820B XMM-Newton observation
- GRB 050820a: NIR Observations by WIRO
- GRB 050820B: Swift XRT position
- GRB050820B: Planned XMM-Newton observation
- GRB050820B: Refined analysis of the Swift-BAT burst
- GRB050820B: BAT-Swift detection of a bright GRB
- Swift/UVOT photometry of GRB050820
- GRB050820: refined XRT analysis
- GRB 050820: Early RAPTOR detections
- GRB 050820 Swift-BAT refined analysis
- GRB 050820: P60 Temporal Decay Index
- GRB 050820: High Resolution Spectroscopy from Keck
- GRB050819: refined XRT analysis
- GRB050819: RTT150 optical observations
- GRB 050820: Swift detection of a GRB
- GRB050820: Optical afterglow from P60
- GRB 050819 Swift-BAT refined analysis
- GRB050819: Swift XRT position
- GRB050819: Swift-BAT detection of a weak burst
- Swift-BAT trigger 150993 is not a GRB
- Swift Trigger 150823 is HETE J1900.1-2455
- GRB 050817: Optical observations
- GRB 050815: Radio Observation
- GRB050814: Radio Observation
- GRB050817: Negative Optical Observations
- GRB050817: Swift-BAT Detection of a burst
- GRB 050814: continued fading
- GRB050815: Optical afterglow detection by Swift UVOT
- GRB050815: XRT refined analysis
- GRB 050813: Radio Observations
- GRB050815: Refined analysis of the Swift-BAT burst
- GRB 050815: ROTSE-III Optical Limits
- GRB050815: Swift XRT afterglow localization
- GRB050815: Swift-BAT detection of a burst
- GRB 050730: Third Epoch WSRT Radio Observations
- GRB050814: Fading red source
- GRB 050813: Gemini Spectra Revisited
- GRB050814: P60 Optical Afterglow Candidate
- GRB 050813: Non-fading of afterglow candidate
- GRB 050814: XRT refined analysis
- GRB050814: SWIFT/UVOT observation
- GRB050814: Refined analysis of the Swift-BAT burst
- GRB050813: Gemini Imaging
- GRB 050813: Gemini spectroscopy and redshifts of galaxies B and C
- GRB 050814: Swift XRT Afterglow Localization
- GRB 050814: Swift detection of a burst
- GRB 050813: Magellan detection of a high redshift galaxy cluster
- GRB050813: RTT150 optical observations
- GRB 050813: I-band observations
- GRB050813, SDSS pre-burst observations
- GRB 050813: KAIT optical limit
- GRB 050813: Swift-BAT refined analysis
- GRB 050813: Photometry of object in XRT error circle
- GRB050813: SWIFT/UVOT observation
- GRB 050813: Swift XRT afterglow localization
- RBO GRB 050714A and GRB 050716 observations
- GRB 050813: Possible Short Swift-BAT GRB
- GRB050813 (Swift 150139): P60 Observations
- Swift-BAT trigger 150131 is not a GRB
- GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE
- Ongoing activity of SGR 1806-20: an intermediate burst 050811
- GRB050803: CrAO optical observations, no OT candidate