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 170428A: GTC spectroscopic redshift of candidate host galaxy
- GRB 170428A: 15 GHz upper limits from AMI
- Swift Trigger 748858: 15 GHz upper limits from AMI
- LIGO/Virgo G268556: Refined localization from CBC parameter estimation
- GRB 170428A: TNG optical observations
- Short GRB 170428A: MASTER-OAFA final reduction of the optical observations
- GRB 170428A: DCT Imaging
- GRB 170428A: TAROT La Silla observatory optical observations
- GRB 170428A: RATIR Afterglow Confirmation
- GRB 170428A: GROND detection of the afterglow
- GRB 170428A: Swift/UVOT Upper Limits
- GRB 170428A: Xinglong 2.16-m upper limit and host galaxy candidate
- GRB 170428A: Swift-XRT refined Analysis
- GRB 170428A: Swift-BAT refined analysis
- Konus-Wind observation of GRB 170428A
- GRB 170428A: MASTER-OAFA early optical observations
- Swift Trigger 750337 is probably a noise fluctuation
- GRB 170428A: Swift detection of a short burst
- Swift trigger 750096 - OT candidate
- GRB170426.95 MASTER-Net OT detection
- Swift Trigger 750096 is probably a noise fluctuation
- Swift Trigger 750044 is probably a noise fluctuation
- GRB 170424A: LCO Observations
- Konus-Wind observation of GRB 170424A
- GRB 170419A: Swift/UVOT Upper Limits
- GRB 170424A: Tiled Swift observations
- GRB 170424A: Fermi GBM detection
- GRB 170424A: Fermi-LAT detection
- GRB 170419A: LCO Observations
- GRB 170423A: Fermi GBM detection
- Swift Trigger 748858: AbAO and TSHAO optical observations
- Fermi GBM trigger 514436208/170421123 is not a GRB
- Swift Trigger 748858: TAROT La Silla observatory optical observations
- Swift Trigger 748858: RATIR Optical and NIR Observations
- GRB 170419B, Swift-BAT refined analysis
- GRB 170419B: Zadko observatory - Gingin optical observations
- GRB 170419A: Zadko observatory - Gingin optical observations
- Fermi GBM trigger 514379207/170420463 is not a GRB
- GRB 170419A: Swift-XRT refined Analysis
- GRB 170412A CALET Gamma-Ray Burst Monitor detection
- GRB 170419B: Fermi GBM observation
- GRB 170419A: Swift-BAT refined analysis
- Swift trigger 748858: Swift BAT, XRT, and UVOT refined analysis
- GRB 170419B: Swift detection of a burst
- GRB 170419A: Enhanced Swift-XRT position
- Swift Trigger 748858: MASTER-OAFA early optical observations
- GRB 170419A: Swift detection of a burst
- Swift Trigger 748858: Zadko observatory - Gingin optical observations
- Swift Trigger 748858: a possible GRB
- LIGO/Virgo G275404: DLT40 follow-up observation
- LIGO/Virgo G277583: DLT40 follow-up observation
- GRB 170409A: TAROT Reunion observatory optical observations
- Konus-Wind observation of GRB 170409A
- GRB 170402A: AstroSat CZTI detection
- GRB 170409A: Fermi GBM Observation
- GRB 170409A: Fermi-LAT detection
- GRB 170405A: SMARTS optical/IR afterglow observations
- GRB 170403B CALET Gamma-Ray Burst Monitor detection
- GRB 170317A: SAO RAS optical observations
- GRB170405A, Swift-UVOT Detection
- GRB 170405A, Swift-BAT refined analysis
- GRB 170405A: Etelman observatory optical observations
- GRB 170405A: Swift-XRT refined Analysis
- GRB 170405A: RATIR Optical and NIR Observations
- Konus-Wind observation of GRB 170405A
- GRB 170405A: LCO FTN observations
- Trigger 745966: Swift detection of 4U1850-03
- GRB 170405A: ISON/Terskol optical observations
- GRB 170405A: Watcher optical detection
- GRB 170405A: Redshift from OSIRIS/GTC
- GRB 170405A: TAROT Reunion observatory optical observations
- GRB 170405A: NOT optical observations
- GRB 170405A: Fermi-LAT detection
- GRB 170405A: Fermi GBM observation
- GRB 170405A: Enhanced Swift-XRT position
- GRB 170405A: Swift detection of a burst with an optical counterpart
- LIGO/Virgo G275697: Update on significance from offline analyses
- LIGO/Virgo G275404: Update on significance from offline analyses
- LIGO/Virgo G275404: European VLBI Network (EVN) follow-up of the near-IR transient in the AGL J1914+1043 field
- GRB 170402A CALET Gamma-Ray Burst Monitor detection
- GRB 170330A CALET Gamma-Ray Burst Monitor detection
- GRB 170325A: optical observations, possible OT/host detection
- Konus-Wind observation of GRB 170403A (short/hard)
- IPN Triangulation of GRB 170403A (short)
- GRB 170403A: Fermi GBM observation
- Konus-Wind observation of GRB 170330A
- IceCube-170321A: Konus-Wind upper limits
- Swift Trigger 745090 is a noise trigger near NGC 5195
- Fermi-LAT Gamma-ray Observations of IceCube-170321
- Swift triggered on SAX J1806.5-221
- GRB 170330A: AstroSat CZTI detection
- GRB 170330A: Swift-BAT refined analysis
- GRB 170331A: Swift-BAT refined analysis
- DOAO 1m telescope V, R, I observation of GRB 170317A
- GRB 170331A: Swift/UVOT Upper Limits
- IceCube-170321A: Swift-XRT observations
- GRB 170330A: Swift-XRT refined Analysis
- GRB 170331A: Swift-XRT refined Analysis
- GRB 170330A: Enhanced Swift-XRT position
- GRB 170331A: Enhanced Swift-XRT position