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 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
- LIGO/VIRGO G298048: Further MeerKAT observations of SSS17a
- GRB 170728B: Kottamia R-band observation
- LIGO/Virgo G298048: Summary of Pi of the Sky observations
- IceCube-170922A: Swift-XRT observations
- LIGO/VIRGO G298048: Latest 3 GHz Detection of Radio Counterpart to SSS17a
- LIGO/Virgo G298048: Limits from further FRB searches of SSS17a
- LIGO/Virgo G298048: MWA Observations of Error Region
- Konus-Wind observation of GRB 170921B
- Correction to GCN Circular 21919: GRB 170921C: Insight-HXMT detection
- IceCube-170922A: HAWC follow-up
- Search for counterpart to IceCube-170922A with ANTARES
- GRB 170921B: AstroSat CZTI detection
- GRB 170906A: Insight-HXMT detection
- LIGO/Virgo G298048: Effelsberg 100-m Radio Telescope observations of SSS17a
- GRB 170921C: Insight-HXMT detection
- IPN Triangulation of GRB 170921B
- INTEGRAL SPI-ACS observation of AMON IceCube-170922A
- IceCube-170922A - IceCube observation of a high-energy neutrino candidate event
- GRB 170921A: RATIR Optical Afterglow Detection and NIR Observations
- LIGO/Virgo G298048: SRT observations of SSS17a in NGC 4993
- GRB 170921A: Swift/UVOT Upper Limits
- GRB 170921A: Swift-BAT refined analysis
- GRB 170918A: Insight-HXMT detection
- GRB 170921A: LCO 2m telescope observations
- GRB 170921A: NOT optical observations
- LIGO/Virgo G298048: LCO FLOYDS and Gemini Spectroscopy
- GRB 170921A: Nanshan optical upper limit
- GRB 170921A: Enhanced Swift-XRT position
- GRB 170921A: MITSuME Okayama upper limits
- GRB 170921A: Swift-XRT refined Analysis
- GRB 170921A: TAROT Calern observatory optical observations