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').
- EP240801a: KAIT optical counterpart observations
- EP240801a: GMG observation
- EP240801a: TRT optical counterpart detection
- EP240801a: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
- GRB 240801B: AstroSat CZTI detection of a bright long burst
- Fermi GRB 240801A: Global MASTER-Net observations report
- GRB 240801A: Fermi GBM Final Real-time Localization
- GRB 240730C: AstroSat CZTI detection of a long burst
- GRB 240731A: Fermi GBM Final Localization
- Fermi trigger No 744128417: Global MASTER-Net observations report
- Fermi trigger No 744083370: Global MASTER-Net observations report
- GRB 240731A: AstroSat CZTI detection
- GRB 240730A: Osservatorio Astronomico Nastro Verde upper limit
- GRB240730A: BOOTES-5/JGT early optical upper limit
- Fermi Gamma-ray Burst Monitor trigger 744061103/240730818 is not a GRB
- Fermi GRB 240730B: Global MASTER-Net observations report
- GRB 240730B: Fermi GBM Final Real-time Localization
- Swift GRB 240730A: Global MASTER-Net observations report
- GRB 240730A: Swift-XRT refined Analysis
- GRB 240715A: Swift-XRT afterglow detection
- GRB 240730A: KAIT Optical Upper Limit
- GRB 240727C: GRBAlpha detection
- GRB 240730A: Swift/UVOT Upper Limits
- GRB 240730A: Enhanced Swift-XRT position
- GRB 240730A: Swift detection of a burst
- Fermi trigger No 743953682: Global MASTER-Net observations report
- GRB 240727A: Swift-BAT refined analysis
- Fermi Gamma-ray Burst Monitor trigger 743953682/240729575 is not a GRB
- LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
- GRB 240727A: observations of optical counterpart.
- GRB 240727B: Swift-XRT observations
- Fermi GRB 240727A: Global MASTER-Net observations report
- GRB 240727A: Swift/UVOT detection
- Fermi trigger No 743868421: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 743868421/240728588 is not a GRB
- GRB 240727A: Correction to time in GCN36960
- GRB 240727A: Osservatorio Astronomico Nastro Verde upper limit
- EP-WXT trigger 01709002661 is not a real source
- GRB 240727A: NOT optical observation
- GRB 240727A: JinShan optical upper limits
- GRB 240727A Bassano Bresciano Observatory upper limit
- GRB 240727D: Correction to the GRB name in GCN 36958
- GRB 240727A: Fermi GBM Final Real-time Localization
- GRB 240727C: AstroSat CZTI detection of a long burst
- GRB 240727A: Swift-XRT refined Analysis
- GRB 240720B: GRBAlpha detection
- GRB 240718A: GRBAlpha detection
- GRB 240710B: GRBAlpha detection
- GRB 240627A: GRBAlpha detection
- Fermi GRB 240726A: Global MASTER-Net observations report
- GRB 240727A: Enhanced Swift-XRT position
- GRB 240727B: Fermi GBM Observation
- Swift GRB240727.16: Global MASTER-Net observations report
- GRB240529A: VIRT optical transient detection
- GRB 240727B: Swift ToO observations
- GRB 240727B: Swift/BAT-GUANO arcminute localization of a long burst
- GRB 240726A: SVOM/GRM observation
- GRB 240727B: AstroSat CZTI detection
- GRB 240726B: AstroSat CZTI detection of a short burst
- GRB240727A: Skynet Optical Afterglow Observations
- GRB 240727A: TRT optical afterglow detection
- GRB 240727A: KAIT Optical Afterglow Candidate
- GRB 240727A: Swift detection of a burst
- GRB 240726A: AstroSat CZTI detection of a short burst
- IceCube-240725A: Upper limits from a search for additional neutrino events in IceCube
- GRB 240726A: Fermi GBM Final Real-time Localization
- Fermi-LAT gamma-ray observations of IceCube-240725A
- IceCube Alert 240725.22: Global MASTER-Net observations report
- IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
- Swift Trigger 1244778 is not a GRB
- Swift GRB240725.11: Global MASTER-Net observations report
- IceCube-240721A: Two candidates from the Zwicky Transient Facility
- GRB 240720A: Swift-BAT refined analysis
- IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
- Fermi trigger No 743418632: Global MASTER-Net observations report
- Fermi trigger No 743315411: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
- Fermi trigger No 743345551: Global MASTER-Net observations report
- Fermi-LAT gamma-ray observations of IceCube-240721A
- Fermi Gamma-ray Burst Monitor trigger 743271526/240721680 is not a GRB
- Fermi trigger No 743219692: Global MASTER-Net observations report
- IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 240721.68: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 743243582/240721356 (GRB 240721A) is not a GRB
- GRB 240720B: SVOM/GRM observation
- GRB 240721A: Fermi GBM Final Real-time Localization
- GRB 240720B: AstroSat CZTI detection of a short burst
- Fermi GRB 240720A: Global MASTER-Net observations report
- GRB 240720A: AstroSat CZTI detection
- GRB 240720A: Fermi GBM observation
- GRB 240720A: Swift detection of a burst
- Swift GRB240720.02: Global MASTER-Net observations report
- Konus-Wind detection of GRB 240718A
- GRB 240713A: SVOM/GRM observation
- Fermi GRB 240718A: Global MASTER-Net observations report
- LAT GRB240718.27: Global MASTER-Net observations report
- GRB 240718A: Fermi GBM Observation
- IceCube-Cascade 240714A: TRT optical observations on the EP/FXT positions
- GRB 240718A: Fermi-LAT Detection