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"- Swift Trigger 796115 is probably not a GRB
- GRB 171205A: VLA detection
- GRB 171205A: UKIRT near-IR observations
- GRB 171209A: LCO 1-m telescope observations
- GRB 171209A: Swift detection of a burst
- Swift Trigger 796098 is probably a noise peak near M31
- LIGO/Virgo GW170817: X-ray observations confirm prediction made from radio data
- GRB 171124A CALET Gamma-Ray Burst Monitor detection
- GRB 171120A CALET Gamma-Ray Burst Monitor detection
- GRB 171106A CALET Gamma-Ray Burst Monitor detection
- LIGO/Virgo GW170817: Further Hubble Space Telescope observations
- LIGO/Virgo G298048: Brightening X-ray Emission from GW170817/GRB170817A/SSS17a
- GRB 171205A: TSHAO optical observations
- GRB 171205A: Detection of the emerging SN
- LIGO/Virgo GW170817: Chandra X-ray brightening of the counterpart 108 days since merger
- GRB 171205A: Continued Swift/UVOT Observations
- LIGO/Virgo G298048: Late-time detection of the X-ray afterglow with Chandra
- Fermi GBM trigger 534174346/171205573 is not a GRB
- GRB 171205A: MASTER-SAAO optical observations of unusual OT
- GRB 171205A: GROND observations of the optical/NIR transient
- GRB 171205A: LCO 1-m telescope observations
- GRB171205A hyperluminal radio afterglow?
- GRB 171205A: GMG observations (2nd night)
- GRB 171205A: Host galaxy photometric properties
- GRB 171205A: CHILESCOPE optical observations
- GRB 171205A: SMARTS optical/IR afterglow observations
- Possible blackbody component in the X-ray spectrum of GRB171205A
- GRB 171205A: GOTO detection of the optical counterpart
- GRB 171205A: TNG NIR detections
- GRB 171205A: LSGT optical afterglow follow-up observation
- GRB 171205A: NOEMA detection of a bright mm afterglow
- GRB 171205A: GMG observation
- Fermi Gamma-ray Burst Monitor trigger 534174346/171205573 is not a GRB
- GRB 171205A: Swift-BAT refined analysis
- GRB 171205A: Swift-XRT refined Analysis
- GRB 171205A: RATIR Optical and NIR Observations
- GRB 171205A: Swift/UVOT Detection
- GRB 171205A: VLT/X-shooter optical counterpart and spectroscopic observations
- GRB 171205A: Enhanced Swift-XRT position
- GRB 171205A: Likely association with low-z spiral galaxy
- GRB 171205A: Swift detection of a burst
- GRB 171126A: AstroSat CZTI detection
- GRB 171124A: TShAO optical observations
- GRB 171124A: Swift-XRT afterglow detection
- Pan-STARRS follow-up of IceCube-171106A
- LIGO/Virgo G299232: LOFAR follow-up
- GRB 171124A: Insight-HXMT/HE detection
- GRB 171126A: Fermi GBM detection
- GRB 171123A: TShAO optical upper limit
- GRB 171124A: AstroSat CZTI detection
- INTEGRAL pointed follow-up of IceCube-171106A
- GRB 171123A: OSN Upper Limit
- GRB 171124A: Swift-XRT observations
- GRB 171124A: Fermi GBM observation
- GRB 171119A: AstroSat CZTI detection
- GRB 171123A: Tautenburg observations
- GRB 171123A: Nanshan-1m optical upper limit
- GRB 171123A: RATIR Optical and NIR Observations
- GRB 171124A: MITSuME Akeno optical upper limits
- GRB 171123A: Swift/UVOT Upper Limits
- GRB 171123A: GMG observation limit
- GRB 171124A: Fermi-LAT detection
- GRB 171124A: Swift ToO observations
- GRB 171123A: MITSuME Akeno optical upper limits
- GRB 171123A: Swift-BAT refined analysis
- GRB 171123A: Swift-XRT refined Analysis
- GRB 171123A: Confirmation of the X-ray afterglow
- GRB 171123A: Enhanced Swift-XRT position
- GRB 171120A: Insight-HXMT detection
- GRB 171123A: Swift detection of a burst
- Konus-Wind observation of GRB 171119A
- IPN Triangulation of GRB 171119A (long)
- GRB 171120A: Xinglong-2.16m optical upper limit
- GRB 171120A: Swift/UVOT Upper Limits
- GRB 171120A: AstroSat CZTI detection
- Konus-Wind observation of GRB 171120A
- GRB171120A: GWAC-F60A upper limit
- GRB 171120A: MITSuME Akeno optical upper limits
- GRB 171120A: Swift-BAT refined analysis
- GRB 171120A: Fermi GBM Detection
- GRB 171120A: Swift-XRT refined Analysis
- GRB 171120A: Fermi-LAT detection
- GRB 171120A: Enhanced Swift-XRT position
- GRB 171115B: Insight-HXMT detection
- GRB 171120A: Swift detection of a burst
- Fermi-LAT Gamma-ray Observations of IceCube-171106A
- GRB 171108B: Insight-HXMT detection
- GRB 171115A: RATIR Optical and NIR Observations
- GRB 171115A: MITSuME Okayama optical upper limits
- GRB 171115A: MITSuME Akeno optical upper limits
- GRB 171115A: Swift-BAT refined analysis
- GRB 171115A: Swift-XRT refined Analysis
- GRB 171115A: Enhanced Swift-XRT position
- GRB 171115A: Swift detection of a burst
- GRB 171112A: Fermi GBM Detection
- LIGO/Virgo G288732/GW170608: updated localization from parameter estimation
- Konus-Wind observation of GRB 171112A
- FACT follow-up of IceCube20171106
- Konus-Wind observation of GRB 171108A
- GRB 171112A: MAXI/GSC detection