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 111005A: VLT optical observations
- GRB 111005A: GROND NIR observations
- GRB 111005A: VLT IR observations
- GRB 111005A: Swift-BAT refined analysis
- GRB 111005A: bright galaxy in error circle
- GRB 111005A: Swift detection of a burst
- GRB 111003A: Fermi GBM detection
- GRB 110905A / MAXI J1836-194: optical monitoring
- GRB 110921A: MITSuME-Akeno Optical photometry
- Skynet/Dolomiti observations of GRB 110928A
- Skynet observations of GRB 110928A
- GRB 110928A: RAPTOR Limits During Gamma-ray Emitting Interval
- GRB 110928A: Swift/UVOT Upper Limits
- Trigger 504307: Swift detection of MAXI J1836-194
- GRB 110928A: Swift-XRT refined Analysis
- GRB 110825A: GROND Observations
- GRB 110928A: Enhanced Swift-XRT position
- GRB 110928A: P60 Observations
- GRB 110928A: Further PAIRITEL NIR Observations
- GRB 110928A: Swift-BAT refined analysis
- GRB 110928A: Swift-XRT observations
- GRB 110928A: Swift/UVOT finding chart observation
- GRB 110928A: PAIRITEL NIR Observations
- GRB 110928A: ROTSE-III Optical Limits
- GRB 110928A: Swift detection of a burst
- Fermi GBM triggers 110923481, 110924391 and 110925200 are not GRBs
- Swift-BAT trigger 503926 is noise
- GRB 110924A: Swift detection of a possible burst
- GCN for GRB 110921B
- GRB 110921A: Swift/UVOT Observations
- GRB110918A: Lick Observations
- GRB 110921A: NOT observations
- GRB 110921A: Fermi GBM observation
- GRB 110921A: TNT astrometry
- GRB 110921A: Swift-XRT refined Analysis
- GRB 110921A, Swift-BAT refined analysis
- GRB 110918A: Liverpool Telescope optical observations
- GRB 110918A: submm observations from APEX
- GRB 110921A: optical observations in Mt. Terskol and Maidanak observatories
- GRB 110921A: Enhanced Swift-XRT position
- GRB 110921A: MITSuME Akeno Optical Observation
- GRB 110921A : TNT optical counterpart candidate
- GRB 110918A: Swift-XRT refined Analysis
- GRB 110918A: Spectroscopy from GTC
- GRB 110921A: MASTER-Net early limit
- GRB 110921A: Swift detection of a burst
- GRB 110915B : X-ray afterglow confirmation
- GRB 110918A: Swift/UVOT Detection of the Optical Counterpart
- GRB 110918A: rest-frame energetics in gamma-gays
- GRB 110918A optical observation
- GRB 110918A: Gemini-N redshift
- GRB 110918A: Afterglow Confirmation from PTF
- GRB 110918A: GROND detection of the afterglow candidate
- GRB 110918A: INT optical detection of Swift candidate afterglow
- GRB 110918A: Swift-XRT observations
- GRB 110918A: pseudo-z= from prompt emission spectrum
- Konus-Wind observation of GRB 110918A
- GRB110918A: BOOTES-1 optical limit
- MAXI/GSC detection of a short soft X-ray transient
- Swift detection of short bursts from PSR J1647-4552
- GRB 110915A: Konus-Wind and Swift/BAT joint spectral analysis
- IPN triangulation of GRB 110918A (long duration, extremely intense)
- GRB 110915B: GROND Observations of the Optical/NIR Afterglow Candidate
- GRB 110915A: Swift/UVOT Upper Limits
- GRB 110915B: Swift/UVOT Upper Limits
- GRB 110915A: GROND Upper limits
- GRB 110915A, Swift-BAT refined analysis
- GRB 110915A: Swift-XRT refined Analysis
- GRB 110915B: Afterglow candidate from OSN
- GRB 110915A: Deep Near-IR Limits from Magellan
- GRB 110915B: XRT afterglow candidate
- GRB 110903A: Suzaku WAM observation of the prompt emission
- GRB 110915A: Deep Gemini-South i/z-band imaging
- GRB110915A MITSuME Okayama J-band upper-limit
- GRB 110915A: MITSuME Okayama and Ishigakijima Optical upper limits
- GRB 110915A: NOT observations
- GRB 110915A: 1.23m CAHA I-band observations
- GRB 110915B: SuperAGILE localization of a long GRB
- GRB 110915A: Enhanced Swift-XRT position
- GRB 110915A: GMG optical upper limit
- GRB 110915A: MITSuME Akeno Optical upper limits
- GRB 110915A: MASTER-Net early limit
- GRB 110915A: Prompt enhanced Swift-XRT position
- GRB 110915A: Swift detection of a burst
- GRB 110825A: Further Swift/XRT Observations
- GRB 110731A: SAO RAS and Terskol observations
- GRB 110906A(?): Burst detection (unconfirmed) from Swift-BAT slew data
- MAXI J1836-194 (originally GRB 110905A): Swift-BAT refined analysis
- GRB 110905A / X-ray transient MAXI J1836-194: TNT optical observation
- GRB 110905A: Potential BAT trigger on MAXI J1836-194
- GRB 110905A: KAIT observations
- GRB 110905A: Swift detection of a burst
- GRB 110903A: Fermi GBM observation
- GRB 110903A: Swift/UVOT Upper Limits
- GRB 110903A: Swift-XRT observations
- Konus-Wind observation of GRB 110903A
- GRB 110903A: a long GRB detected by INTEGRAL
- GRB 110820A: optical upper limit
- SGR Swift J1834.9-0846: Correction to the Swift-BAT refined spectral analysis
- Trigger 502024: Swift detection of KS 1741-293