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.
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"4252 results found.
- EP250919a: Global MASTER-Net observations report
- GRB 250916A: Fermi GBM Observation
- GRB 250916A: further SAO RAS optical observations
- GRB 250916A: Glowbug gamma-ray detection
- GRB 250917B: Swift detection of a short burst
- GRB 250916A: AstroSat CZTI detection of a bright long burst
- GRB 250916A: Fermi GBM Final Real-time Localization
- GRB 250911A: Insight-HXMT detection
- LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
- GRB 250911A: GECAM-B detection
- GRB 250911A: Swift-BAT refined analysis
- GRB 250910B: SVOM/GRM observation
- EP250911a: Swift-XRT observations
- EP250911a: COLIBRÍ optical observations
- Fermi GRB 250910B: Global MASTER-Net observations report
- EP250911a: LCO optical counterpart discovery
- EP250910a: Global MASTER-Net observations report
- EP#01709240653: Swift-XRT observations
- EP250908c: SVOM/VT optical observation
- EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
- EP250908b: SVOM/VT optical candidate
- EP250908c: Global MASTER-Net observations report
- EP250905b: Global MASTER-Net observations report
- IceCube Alert 250905.84: Global MASTER-Net observations report
- IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
- GRB 250902A: VZLUSAT-2 detection
- EP-WXT trigger 01709201209: Liverpool Telescope upper limits
- Fermi GRB 250902B: Global MASTER-Net observations report
- IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
- EP250827b: Swift observations of AT 2025wkm
- EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
- GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
- GRB 250831A: SVOM detection of a soft burst
- EP-WXT trigger 01709200994: Liverpool Telescope upper limits
- EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
- GRB 250830A / MAXI J0853+337: MAXI/GSC detection
- The EP-WXT trigger 01709200994 is likely a flaring star
- EP250821a: SOAR observations
- LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
- EP250828a: Liverpool Telescope upper limits
- Swift GRB 250828B: Global MASTER-Net observations report
- EP250828a: Global MASTER-Net observations report
- EP250827a: Swift/UVOT Detection
- Fermi GRB 250827A: Global MASTER-Net observations report
- EP250827a: Swift-XRT counterpart detection
- EP250827a: Global MASTER-Net observations report
- EP250827a: Gemini-South optical counterpart detection
- Fermi GRB 250824B: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250818k: COLIBRÍ confirmation of rebrightening of AT2025ulz
- LIGO/Virgo/KAGRA S250818k: GOTO counterpart search and upper limits
- EP250821a: Einstein Probe detection of an X-ray transient
- LIGO/Virgo/KAGRA S250818k: Multi-band Gemini GMOS Detections
- LIGO/Virgo/KAGRA S250818k: AstroSat CZTI non-detection and upper limits
- LIGO/Virgo/KAGRA S250818k: Properties of the low-significance GW compact binary merger candidate potentially associated with AT 2025ulz
- Fermi trigger No 776849714: Global MASTER-Net observations report
- GRB 250818B: SVOM detection of a short burst
- GRB 250815A: Fermi GBM Final Localization
- GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
- GRB 250814A: Possible afterglow candidate from P200/WIRC
- Fermi trigger No 776818276: Global MASTER-Net observations report
- IceCube-250813A: Upper limits from a search for additional neutrino events in IceCube
- IceCube Alert 250813.14: Global MASTER-Net observations report
- Fermi GRB 250808A: Global MASTER-Net observations report
- Swift GRB250807.65: Global MASTER-Net observations report
- The EP-WXT trigger 01709198251 is likely a flaring star
- LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
- LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
- LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
- LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
- GRB 250728A: COLIBRÍ optical upper limit
- Fermi trigger No 775387550: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
- GRB 250727A: EP-FXT counterpart detection
- LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
- Swift detection of the Soft Gamma Repeater PSR J1647-4552
- Swift GRB 250725A: Global MASTER-Net OT detection
- Fermi GRB 250725A: Global MASTER-Net observations report
- Swift GRB 250725A: Global MASTER-Net observations report
- GRB 250721A: MAXI/GSC detection
- Fermi trigger No 774730635: Global MASTER-Net observations report
- GRB 270713A: Kitab and AbAO Optical Observations
- Konus-Wind detection of GRB 250716A
- GRB 250716A: GOTO tentative optical counterpart candidate
- GRB 250716A: Fermi GBM Observation
- GRB 250716A: Fermi GBM Final Real-time Localization
- GRB 250706B/C: 7DT Follow-up Observations
- Fermi GRB 250711A: Global MASTER-Net observations report
- GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
- EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
- IceCube-250706A: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
- GRB 250702F: Fermi GBM Observation
- GRB 250702F: Leavitt Observatory optical observations
- EP250702a: Global MASTER-Net observations report
- GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
- Fermi GRB 250702F: Global MASTER-Net observations report
- Fermi GRB 250702C: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 772838080/250628885 is not a GRB
- LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate