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"20951 results found.
- GRB 260903A: SAO RAS optical upper limit
- Fermi GRB 260907A: Global MASTER-Net observations report
- EP260903a: EP-FXT follow-up observation
- EP Alert 260905.11: Global MASTER-Net observations report
- GRB 260903A: J-band upper limit with WINTER
- EP Alert 260903.47: Global MASTER-Net observations report
- GRB 260903A: SVOM/ECLAIRs refined analysis
- GRB260903A: Liverpool Telescope optical observations
- GRB 260903A: SAO RAS optical observations
- EP260903a: EP-WXT detection of a fast X-ray transient
- EP Alert 260903.62: Global MASTER-Net observations report
- GRB 260903A: OHP/T193 optical afterglow detection
- GRB 260903A: NOT optical observations and afterglow fading
- NuSTAR Transient 260828: SOAR Optical Upper Limits
- SVOM GRB260903A: Global MASTER-Net observations report
- GRB 260903A: LCO optical observations
- GRB 260903A: SVOM/VT optical candidate
- GRB 260818A: ATCA detection of a candidate radio counterpart
- EP260901a: Global MASTER-Net observations report
- IceCube-260827A: No transient candidates from the Zwicky Transient Facility
- GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
- NuSTAR Transient 260828: LCO Optical Upper Limits
- EP260901a: EP-WXT detection of a fast X-ray transient
- EP260830a: Global MASTER-Net observations report
- EP260830a: EP-WXT detection of a fast X-ray transient
- NuSTAR 260828: a 1100s hard X-ray transient
- EP260727a: ATCA 10 GHz detection
- Fermi-LAT Gamma-ray Observations of IceCube-260827A
- Fermi-LAT Gamma-ray Observations of IceCube-260825A
- GRB 260818B: VLT optical and nIR observations
- GRB 260818B: TNG NIR observations
- MAXI GRB260827.40: Global MASTER-Net observations report
- The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
- GRB 260818B: 6 GHz VLA observations
- GRB 260818B: SVOM/VT optical upper limit and continuous observations
- GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
- GRB 260808B: SAO RAS observations of the optical rebrightening
- EP260822a: Global MASTER-Net observations report
- EP Alert 260820.31: Global MASTER-Net observations report
- IceCube-260825A: No transient candidates from the Zwicky Transient Facility
- GRB 260807A: EP-FXT follow-up observations
- GRB 260822A: SVOM/ECLAIRs refined analysis
- GRB 260809A: SVOM/ECLAIRs refined analysis
- GRB 260822A: SVOM/VT optical upper limits
- IceCube Alert 260825A: Global MASTER-Net observations report
- GRB 260822A: PRIME near-infrared upper limits from multiple epochs
- GRB 260822A: EP/FXT follow-up observations
- GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
- GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
- GRB 260822A: GOTO optical counterpart detection
- GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
- GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
- EP260822a: Einstein Probe detection of a fast X-ray transient
- GRB 260822A: LCO optical upper limits
- GRB 260822A: GOTO optical upper limit
- GRB 260822A: SVOM detection of a short burst
- Fermi-LAT Gamma-ray Observations of IceCube-260821A
- Fermi-LAT Gamma-ray Observations of IceCube-260807A
- GRB 260818B: VLA radio observations
- GRB 260818B: SVOM/C-GFT optical upper limit
- IceCube Alert 260821A: Global MASTER-Net observations report
- GRB 260818A: J-band observations with WINTER
- GRB 260818B: SVOM/ECLAIRs refined analysis
- GRB 260818A: SVOM/ECLAIRs refined analysis
- GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- EP260806a: SAO RAS multicolor optical observations
- EP260812a: AbAO optical upper limit
- GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- EP260806a: NUTTELA-TAO optical observations
- EP260812a: AZT-22 optical upper limit
- EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
- EP260806a: WFST optical observations
- EP260812b: Optical upper limit with Kinder
- GRB 260808B: Liverpool Telescope further optical observations
- EP260812a: NOT and Liverpool Telescope upper limits:
- EP260812b: Liverpool Telescope observations
- EP260812b: GOTO detection of the optical counterpart
- EP260812a: SVOM/C-GFT optical upper limit
- EP260812b: COLIBRÍ optical observations
- EP trigger #01709278129 (EP260812b?): NOT optical counterpart
- GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
- GRB 260809A: SAO RAS optical observations
- GRB 260808B: SAO RAS optical observations
- GRB 260808B: SVOM/VT optical re-brightening at day 3
- GRB 260807A: SVOM/ECLAIRs refined analysis
- EP260806a: MAO/AZT-22 optical observations
- GRB260808B: MAO/AZT-22 optical observations
- GRB 260809A: J-band upper limit with WINTER
- GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
- GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
- GRB 260809A: NOT optical observations
- GRB260809A: MAO/AZT-22 optical observations
- GRB260809A: OHP/T193 optical observations
- GRB 260809A: SVOM/VT optical counterpart
- EP260809a: J-band upper limit with WINTER
- GRB 260808B: J-band upper limit with WINTER
- GRB 260808B: SVOM/ECLAIRs refined analysis
- GRB 260808B: Liverpool Telescope optical observations
- GRB 260808B: NOT optical observations
- GRB 260808B: LCO optical observations