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 171020A: LT observations
- GRB 171020A: Correction of alpha in GCN 22031
- GRB 171020A: Confirmation of OT fading
- GRB 171020A: Mini-MegaTORTORA upper limits on simultaneous optical emission
- GRB 171020A: NOT optical afterglow detection
- GRB 171020A: Swift detection of a burst
- Fermi-GBM Detection of possible burst from AXP CXOU J164710.2-455216/PSR J1647-4552
- GRB 171011B: Insight-HXMT detection
- Trigger 780207: Swift triggers again on AXP CXOU J164710.2-455216/PSR J1647-4552
- Swift Trigger on AXP CXOU J164710.2-455216/PSR J1647-4552
- GRB 171010B: Swift-XRT afterglow detection
- GRB 171011B CALET Gamma-Ray Burst Monitor detection
- Trigger 779762: Swift detection of Vela X-1
- Trigger 779351: Swift detection of Swift J0243.6+6124
- Search for counterpart to IceCube-171015A with ANTARES
- INTEGRAL SPI-ACS observation of IceCube-171015A
- Swift trigger 779171 is probably a noise fluctuation
- IceCube-171015A - IceCube observation of a high-energy neutrino candidate event
- GRB 171010A: VLA Observations
- GRB 171010A: VLA Detection
- GRB 171010A: A detection of a radio source by AMI
- GRB 171010A : Optical observations from HCT
- GRB 171010A: RATIR Optical and NIR Observations
- BAT trigger 778435 is not a GRB.
- GRB 171010B: Swift-XRT observations
- GRB 171013A: TAROT Calern observatory optical observations
- GRB 171013A: Swift detection of a possible burst
- GRB 171011A: Swift-BAT refined analysis
- Konus-Wind observation of GRB 171011B
- GRB 171010A: Swift/UVOT Detection
- Konus-Wind observation of GRB 171010A
- GRB 171010A: ePESSTO NTT spectroscopic redshift
- GRB 171010A: MITSuME Akeno Optical Observation
- GRB 171010A: NOT optical observations
- GRB 171010B: Fermi GBM detection
- IPN Triangulation of GRB 171011B (long/very bright)
- GRB 171010B: Swift ToO observations
- GRB 171011A: TAROT Calern observatory optical observations
- GRB 171010B: Swift detection of a burst
- GRB 171011A: MASTER-SAAO optical observations
- GRB 171011A: Swift detection of a burst
- GRB 171010A: Fermi GBM observation
- GRB 171010A: LCO 1m telescope observations
- GRB171010A: AstroSat CZTI detection
- GRB 171010A: Swift-XRT afterglow detection
- GRB 171010A: optical observations
- GRB 171010A: OT, spectrum, and possible host galaxy
- GRB 171010A: Swift ToO observations
- GRB 171010A: Fermi-LAT detection
- GRB 171007A: Swift/UVOT Upper Limits
- LIGO/Virgo G298048/GW170817: updated localization from parameter estimation
- LIGO/Virgo G298048: Mid-Infrared Spitzer/IRAC Observations at 3.6 and 4.5 microns
- GRB 171007A: Swift-BAT refined analysis
- GRB 171007A: Fermi GBM observation
- GRB 171007A: Enhanced Swift-XRT position
- GRB 171007A: Swift-XRT refined Analysis
- GRB 171007A: RATIR Optical and NIR Observations
- GRB 171007A: Swift detection of a burst
- LIGO/Virgo G298048: LWA radio observations
- GRB 171004A: Swift/UVOT Upper Limits
- GRB 171004A: Swift-BAT refined analysis
- GRB 171004A: Correction to RATIR Astrometry and Photometry
- GRB 171004A: Swift-XRT refined Analysis
- GRB 171004A: Enhanced Swift-XRT position
- LIGO/Virgo G299232: SWASP optical imaging coverage
- GRB 171004A: RATIR Optical and NIR Observations
- GRB 170710A: LCO Observations
- GRB 171004A: Swift detection of a burst
- GRB 171003A: Enhanced Swift-XRT position
- LIGO/Virgo G299232: MAGIC Cherenkov Telescopes observations
- Swift Trigger 775946 is a Galactic transient, not GRB 171003
- LIGO/Virgo G299232: LOFAR follow-up
- GRB 171003A: LT early optical observations
- GRB 171003A: Swift detection of a burst or a Galactic Transient
- GRB 171001A: RATIR Optical and NIR Observations
- GRB 171001A: Swift-BAT refined analysis
- GRB 171001A: Nanshan-0.36m optical afterglow detections
- GRB 171001A: Swift-XRT refined Analysis
- GRB 171001A: Swift/UVOT Detection
- GRB 171001A: IRSF Observation
- GRB171001A: D50 optical limit
- GRB 171001A: Enhanced Swift-XRT position
- GRB 170921A: 15 GHz upper limits from AMI
- GRB 170903A: 15 GHz upper limits from AMI
- GRB 170906C: 15 GHz upper limits from AMI
- GRB 170823A: 15 GHz upper limits from AMI
- GRB 170822A: 15 GHz upper limits from AMI
- GRB 171001A: Swift detection of a burst
- LIGO/VIRGO G299232: AMI-LA Observations of the optical transient Swift J014008.5+343403.6
- Fermi Gamma-ray Burst Monitor trigger 528508320/170930994 is not a GRB
- Fermi Gamma-ray Burst Monitor trigger 528330888/170929011 is not a GRB
- 3.6m Devasthal Optical Telescope observations of GRB 170428A
- Further Swift-XRT observations of IceCube 170922A
- LIGO/Virgo G298048: Record of all e-MERLIN results to date on SSS17a
- LIGO/Virgo G298048: Further European VLBI Network (EVN) observations of SSS17a
- LIGO/Virgo G299232/GW170825: serendipitous XMM-Newton slew observations
- LIGO/Virgo G298936/GW170823: serendipitous XMM-Newton slew observations
- Fermi-GBM GRB misclassifications
- LIGO/VIRGO G298048: VLA detection of the radio counterpart at 6 GHz
- LIGO/Virgo G297595/GW170814: updated localization from parameter estimation