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 151021A: MITSuME Okayama Ks-band upper-limit
- GRB 151021B: Fermi GBM detection
- Konus-Wind observation of GRB 151021A
- GRB 151021A: Swift/UVOT Detection
- GRB 151021A: MITSuME Okayama upper limits
- GRB 151021A: Swift-XRT refined Analysis
- GRB 151021A: Swift-BAT refined analysis
- GRB 151021A: Enhanced Swift-XRT position
- GRB 151021A: MASTER-NET bright OT detection
- GRB 151021A: Optical counterpart and redshift from X-shooter
- GRB 151021A: Swift detection of a burst
- LIGO/Virgo G184098: LOFAR follow-up
- GRB 151004A: Swift-XRT follow-up observations
- GRB 151006A: Astrosat CZTI detection
- Trigger 659734: Swift detection of SAX J1750.8-2900 or other source near Galactic center
- LIGO/Virgo G184098: VLA follow-up of iPTF15cyk
- Fermi GBM trigger 466602792/151015495 is not a GRB
- LIGO/VIRGO G184098 : PESSTO classifications of PanSTARRS transients in the northern region
- Fermi GBM trigger 466316973/151012187 is not a GRB
- GRB 151006A: Mondy optical upper limit
- GRB 151006A: MITSuME Akeno optical upper limits
- Fermi GBM trigger 466059859/151009211 is not a GRB
- Konus-Wind observation of GRB 151006A
- Swift Trigger 658045 is not a GRB
- GRB 151006A: OSN optical upper limit
- GRB 151006A: Swift-BAT refined analysis
- GRB 151006A: MITSuME Okayama Ks-band upper-limit
- GRB 151006A: Swift-XRT refined Analysis
- GRB 151006A: Fermi-LAT detection
- GRB 151006A: Swift/UVOT Upper Limits
- GRB 151006A: Fermi GBM detection
- GRB 151006A: Enhanced Swift-XRT position
- GRB 151006A: MITSuME Okayama upper limits
- Konus-Wind observation of GRB 151001B
- GRB 151006A: Kanata/HOWPol optical imaging polarimetry
- GRB 151006A: Prompt enhanced Swift-XRT position
- GRB 151006A: Swift detection of a burst
- LIGO/Virgo G184098: Further VST-ESO PARANAL observations
- Trigger 657564 / GRB 151004A: Swift BAT and XRT refined analysis
- LIGO/VIRGO G184098 : PESSTO classification of PS15cbm in the northern region
- LIGO/Virgo G184098: ongoing Pan-STARRS search for optical transients
- Trigger 657564 / GRB 151004A: Swift/UVOT Upper Limits
- Swift Trigger 657564: MASTER-NET early optical observations.
- Swift Trigger 657564: XRT prompt analysis
- LIGO/Virgo G184098: MASTER OTs detection and Scenario Machine prediction
- Swift Trigger 657564: a probable GRB
- LIGO/Virgo G184098: Ongoing gravitational-wave analysis
- GRB 151001A: Swift-BAT refined analysis
- GRB 151001A: RATIR Observations
- GRB 151001B: Swift/UVOT Upper Limits
- GRB 151001B: Swift-XRT refined Analysis
- GRB 151001B: Swift-BAT refined analysis
- GRB 151001A: Swift/UVOT Detection
- GRB 151001B: MASTER-NET early optical observations.
- GRB 151001A: NOT imaging
- GRB 151001A: Swift-XRT refined Analysis
- GRB 151001B: Enhanced Swift-XRT position
- GRB 151001A: Enhanced Swift-XRT position
- GRB 151001A: Fermi GBM detection
- GRB 151001B: Swift detection of a burst
- GRB 151001A: Swift detection of a burst with an optical counterpart
- LIGO/Virgo G184098: spectral classification of PS15cci
- LIGO/Virgo G184098: Update to LT Spectroscopy of PS15ccx
- LIGO/Virgo G184098: Liverpool Telescope Spectroscopy of PS15ccx
- GRB 150925A: Swift/UVOT Upper Limits
- GRB 150925A: Swift-BAT refined analysis
- GRB 150925A: Swift-XRT refined Analysis
- GRB 150925A: Enhanced Swift-XRT position
- GRB 150925A: Swift detection of a burst
- LIGO/Virgo G184098: LOFAR follow-up
- LIGO/Virgo G184098: ASKAP followup
- LIGO/Virgo G184098: ongoing Pan-STARRS search for optical transients
- LIGO/Virgo G184098: optical transient search with Kiso Schmidt telescope and KWFC on behalf of J-GEM collaboration
- Konus-Wind observation of GRB 150922A
- LIGO/VIRGO G184098 : classifications of transients from the LSQ observations
- GRB 150922A: Fermi GBM observation
- IPN Triangulation of GRB 150922A (short/hard)
- Konus-Wind observation of GRB 150919A
- IPN Triangulation of GRB 150919A (short / hard)
- LIGO/Virgo G184098: INTEGRAL search of temporally coincident prompt hard X-ray emission
- LIGO/Virgo G184098: transient search with VISTA
- ANTARES neutrino detection: Fermi GBM Observations
- Fermi GBM trigger bn150920977 is not due to a GRB
- LIGO/Virgo G184098: DESGW followup program
- LIGO/Virgo G184098: SkyMapper observations
- LIGO/Virgo G184098: TAROT network optical observations
- LIGO/Virgo G184098: La Silla - QUEST Followup
- LIGO/Virgo G184098: Swift follow-up observations
- LIGO/Virgo G184098: MWA Followup
- LIGO/Virgo G184098: DESGW followup program
- LIGO/Virgo G184098: Pan-STARRS1 observations of the northern sky region
- LIGO/Virgo observing run 1 (O1) starts 2015-09-18 15:00 UTC
- LIGO/Virgo G184098: Keck II DEIMOS Spectra of iPTF Optical Candidates
- LIGO/Virgo G184098: Nearby Galaxies in Error Circle
- LIGO/Virgo G184098: Fermi-GBM ground-based follow-up
- LIGO/Virgo G184098: Observations from the TOROS collaboration
- LIGO/Virgo G184098: iPTF Optical Transient Candidates
- LIGO/Virgo G184098: VST-ESO PARANAL observations
- LIGO/Virgo G184098: Pan-STARRS1 observations of the northern sky region
- Instructions for reporting follow-up observations related to LIGO/Virgo G184098