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"18241 results found.
- GRB 260915A: REM optical/NIR observations
- GRB 260914A: REM optical/NIR observations
- GRB 260914A: VLT/X-shooter observations and redshift confirmation
- GRB 260915A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB 260915A: NOT optical upper limit
- GRB 260915A: SVOM/VT optical upper limits from VHF data
- GRB 260915A: LCO optical upper limits
- GRB 260914A: EP-FXT follow-up observation
- GRB 260915A: SVOM detection of a burst
- GRB 260914A: LCO optical observation
- GRB 260914A: SVOM/C-GFT optical observations
- GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
- GRB 260914A: SVOM detection of a burst
- GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
- GRB 260913A: SVOM/C-GFT optical upper limit
- GRB 260913A: SVOM detection of a faint burst
- GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
- GRB 260907A: SVOM/GRM observation
- GRB 260909A: CrAO and AbAO optical upper limits
- GRB 260909A: KAIT optical upper limit
- GRB 260903A: Swift-XRT observations
- GRB 260909A: OHP/T193 z-band upper limit
- GRB 260909A: VLT optical and near-infrared upper limits
- GRB 260909A: EP-FXT follow-up observation
- EP260806a: NOEMA detection
- EP260623a: NOEMA detections
- GRB 260909A: Mondy optical observations and afterglow candidate
- GRB 260909A: Xinglong 2.16m optical upper limit
- GRB 260909A: SVOM/C-GFT optical upper limit
- GRB 260909A: SVOM detection of a burst
- The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
- GRB 260903A: SAO RAS optical upper limit
- The EP-WXT trigger 01709305715 is likely a flaring star
- EP260903a: EP-FXT follow-up observation
- The EP-WXT trigger 01709302592 is likely a flaring star
- GRB 260903A: J-band upper limit with WINTER
- GRB260903A: Liverpool Telescope optical observations
- GRB 260903A: SAO RAS optical observations
- EP260903a: EP-WXT detection of a fast X-ray transient
- GRB 260830A: Insight-HXMT/HE detection
- GRB 260903A: EP-FXT follow-up observation
- GRB 260903A: OHP/T193 optical afterglow detection
- NuSTAR Transient 260828: SOAR Optical Upper Limits
- GRB 260903A: LCO optical counterpart detection
- EP260901a: SVOM/VT optical upper limits
- EP260901a: EP-FXT follow-up observation
- GRB 260829A: SVOM/GRM observation
- GRB 260818A: ATCA detection of a candidate radio counterpart
- EP260830a: EP-FXT follow-up observation
- EP260901a: Global MASTER-Net observations report
- GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
- NuSTAR Transient 260828: LCO Optical Upper Limits
- EP260901a: EP-WXT detection of a fast X-ray transient
- GRB 260831B: EP-FXT follow-up observation
- GRB 260831B: LCO optical upper limits
- EP260830a: EP-WXT detection of a fast X-ray transient
- GRB 260827A: SVOM/GRM observation
- GRB 260831B: SVOM detection of a possible burst
- GRB 260825A: SVOM/GRM observation of a long burst
- GRB 260818B: Further EP-FXT observation
- GRB 260818B: VLT optical and nIR observations
- GRB 260818B: TNG NIR observations
- The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
- GRB 260818B: 6 GHz VLA observations
- GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
- GRB 260808B: SAO RAS observations of the optical rebrightening
- 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
- EP260822a: EP-FXT non-detection and upper limit
- 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
- The EP-WXT trigger 01709287395 is likely a flaring star
- GRB 260822A: GROWTH-India Telescope Upper Limits
- GRB 260818B: VLA radio observations
- GRB 260818B: SVOM/C-GFT optical upper limit
- The EP-WXT trigger 01709286204 is likely a flaring star
- EP detected a brightening of LMXB 1ES 1735-26.9
- GRB 260818B: EP-FXT follow-up observation
- GRB 260818A: J-band observations with WINTER
- GRB 260818B: NOT optical upper limits
- GRB 260810A: SVOM/GRM observation
- GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- GRB260818A: EP-FXT follow-up observation
- GRB 260818B: LCO optical upper limits
- EP260806a: SAO RAS multicolor optical observations
- GRB 260818A: LCO optical upper limits
- EP260812a: AbAO optical upper limit
- GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
- EP260806a: NUTTELA-TAO optical observations
- The EP-WXT trigger 01709281429 is likely a flaring star
- EP260812a: AZT-22 optical upper limit
- EP260806a: WFST optical observations
- The EP-WXT trigger 01709280562 is likely a flaring star
- EP260812b: Optical upper limit with Kinder
- The EP-WXT trigger 01709279838 is likely a flaring star
- GRB 260805D: SVOM/GRM detection of a possible magnetar burst
- GRB 260808B: Liverpool Telescope further optical observations