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 170127A: GROND Upper limits
- GRB 170127C: AstroSat CZTI detection
- GRB 170127B: Swift-XRT refined Analysis
- GRB 170124A: POLAR Observation
- GRB 170127A: Swift-XRT refined Analysis
- GRB 170126A, Swift-BAT refined analysis
- GRB 170124A: CALET Gamma-Ray Burst Monitor detection
- Swift Trigger 735413 is not an astrophysical event
- GRB 170127B: Swift/UVOT Upper Limits
- LIGO/Virgo G268556: FLOYDS Spectrum of iPTF17cf/PS17fr Favors an AGN Classification
- GRB 170127A: Swift/UVOT Upper Limits
- GRB 170127B: Fermi GBM observation
- GRB 170127B: Enhanced Swift-XRT position
- GRB 170127B: NOT r-band upper limits
- GRB 170127A: Enhanced Swift-XRT position
- Konus-Wind observation of GRB 170126A
- GRB 170127C: Tiled Swift observations
- GRB 170127C (Fermi/GBM trigger 507173752): AGILE analysis
- GRB 170127C: Fermi-LAT detection
- GRB 170127C: Fermi GBM detection
- LIGO/Virgo G270580: HAWC follow-up observations
- GRB 170127B: MASTER-Kislovodsk early optical observations
- GRB 170127B: Swift detection of a short burst
- GRB 170127A: Prompt enhanced Swift-XRT position
- GRB 170127A: Swift detection of a burst
- GRB 170126A: AstroSat CZTI detection
- LIGO/Virgo G270580: Swift/UVOT follow-up of PS17yt
- GRB 170126A: Swift-XRT refined Analysis
- GRB 170126A: Swift/UVOT Detection of a Fading Afterglow
- GRB 170126A: Fermi GBM observation
- LIGO/Virgo G270580: Fermi GBM Observations
- GRB 170126A: Enhanced Swift-XRT position
- GRB 170126A: Swift detection of a burst with an optical counterpart
- GRB 170115A: 15 GHz upper limits from AMI
- LIGO/Virgo G270580: MAXI/GSC observations
- LIGO/Virgo G270580: NOT observations of PS17yt
- LIGO/Virgo G270580: Liverpool Telescope classification of EM candidates
- GRB 170115B: AGILE/SuperAGILE localisation
- LIGO/Virgo G270580: Asiago 1.82m observations of PS17ua and PS17yt
- LIGO/Virgo G270580: Swift-XRT follow-up of PS17yt
- LIGO/Virgo G270580: GMG photometric follow-up of PS17yt
- LIGO/Virgo G270580: 10.4m GTC spectroscopic observations of PS17yt
- LIGO/Virgo G270580: No change to estimate of LIGO false alarm probability
- LIGO/Virgo G270580: Liverpool Telescope classification of EM candidates
- LIGO/Virgo G270580: Pan-STARRS coverage and 124 optical transients
- LIGO/Virgo G268556: ANTARES upper limits
- GRB 170121B: AbAO optical observations
- LIGO/Virgo G270580: UL50 observations
- GRB 170121B: MASTER early optical observations of the Swift possible XT
- LIGO/Virgo G270580: CALET Observations
- LIGO/Virgo G270580: Pan-STARRS coverage and bright, rising transient PS17yt
- GRB 170121B: AstroSat CZTI detection
- GRB 170121B: Swift-XRT and UVOT observations
- LIGO/Virgo G270580/GW170120 : Asiago observations
- GRB 170121B: LCO FTN observations
- LIGO/Virgo G268556/GW170104: MAXI/GSC observations
- LIGO/Virgo G270580: A third optical transient from CNEOST
- GRB 170121B: Fermi GBM detection
- GRB 170121B: Swift ToO observations
- LIGO/Virgo G270580: ATLAS coverage and 4 optical transients
- GRB 170121B/Fermi trigger 506702667 MASTER-Amur OT detection
- GRB 170121A: POLAR Observation
- GRB 170120A: POLAR Observation
- LIGO/Virgo G270580: Fermi-LAT search for a high-energy gamma-ray counterpart
- LIGO/Virgo G270580: Two optical counterpart candidates from CNEOST
- LIGO/Virgo G270580: INTEGRAL search of temporally coincident prompt hard X-ray
- LIGO/Virgo G270580: Swift-XRT sources
- LIGO/Virgo G270580: Swift/BAT data search
- LIGO/Virgo G268556: Global MASTER Net 21 OTs detection
- LIGO/Virgo G270580: Mini-MegaTORTORA follow-up observations
- LIGO/Virgo G270580: Pan-STARRS and ATLAS observations of the skymap
- LIGO/Virgo G270580: Observations of initial skymap by Project Mini-GWAC of SVOM
- LIGO/Virgo G270580: AGILE MCAL and Super-AGILE Observations
- LIGO/Virgo G270580 ANTARES search
- LIGO/Virgo G270580: Identification of a GW Burst Candidate
- LIGO/Virgo G268556: RATIR Observation of iPTF Candidates
- GRB 170117A: Swift/UVOT Upper Limits
- GRB 170115B: CALET Gamma-Ray Burst Monitor detection
- GRB 170117A: Swift-XRT observations
- GRB 170117A: Swift ToO observations
- Swift Trigger #733426: possible detection of a burst or transient
- GRB 170115A : AbAO optical upper limit
- GRB 170115A: Swift/UVOT Upper Limits
- GRB 170115B: Swift-XRT observations
- Konus-Wind observation of GRB 170115B
- IPN Triangulation of GRB 170115B
- GRB 170115B: AGILE detection
- LIGO/Virgo G268556: Swift-XRT observations of iPTF17cw
- GRB 170112A : AbAO optical observations
- GRB 170115A: Swift-BAT refined analysis
- GRB 170115A: Swift-XRT refined Analysis
- GRB 170114B: POLAR Observation
- GRB 170114A: POLAR Observation
- GRB 170115B: Tiled Swift observations
- GRB 170115B: AstroSat CZTI (Veto) detection
- GRB 170115A: Enhanced Swift-XRT position
- GRB 170115B: Fermi-LAT detection
- GRB 170115B: Fermi GBM detection
- GRB 170115A: Swift detection of a burst
- GRB 170114A: Fermi GBM detection