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"26867 results found.
- GRB 260907A: SVOM/GRM observation
- GRB 260909A: CrAO and AbAO optical upper limits
- GRB 260909A: SVOM/ECLAIRs refined analysis
- GRB 260910B: GOTO tentative optical counterpart candidates
- GRB 260910B: Fermi GBM Final Real-time Localization
- EP Alert 260909.53: Global MASTER-Net observations report
- GRB 260909A: EP-FXT follow-up observation
- GRB 260910A: Fermi GBM Final Real-time Localization
- GRB 260909A: SVOM/VT optical upper limits
- GRB 260909A: SVOM/GRM observation
- 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
- Fermi trigger No 810554827: Global MASTER-Net observations report
- EP Alert 260908.60: Global MASTER-Net observations report
- Fermi GRB 260907B: Global MASTER-Net observations report
- The EP-WXT trigger 01709305715 is likely a flaring star
- GRB 260907B: Fermi GBM Final Real-time Localization
- Fermi GRB 260907A: Global MASTER-Net observations report
- GRB 260907A: Fermi GBM Final Real-time Localization
- EP260903a: EP-FXT follow-up observation
- EP Alert 260905.11: Global MASTER-Net observations report
- The EP-WXT trigger 01709302592 is likely a flaring star
- 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 260830A: GECAM-B detection of a burst
- EP260903a: EP-WXT detection of a fast X-ray transient
- EP Alert 260903.62: Global MASTER-Net observations report
- GRB 260903A: EP-FXT follow-up observation
- GRB 260903A: NOT optical observations and afterglow fading
- SVOM GRB260903A: Global MASTER-Net observations report
- GRB 260903A: LCO optical observations
- GRB 260903A: SVOM/VT optical candidate
- GRB 260831A: GECAM-B observation
- GRB 260903A: LCO optical counterpart detection
- GRB 260903A: SVOM detection of a soft faint burst
- 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
- GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
- EP260901a: EP-WXT detection of a fast X-ray transient
- SVOM trigger sb26083106 is not a GRB
- GRB 260831B: EP-FXT follow-up observation
- GRB 260831B: LCO optical upper limits
- EP260830a: Global MASTER-Net observations report
- EP260830a: EP-WXT detection of a fast X-ray transient
- GRB 260827A: SVOM/GRM observation
- GRB 260831B: SVOM detection of a possible burst
- IPN triangulation of GRB 260829A
- EP260727a: ATCA 10 GHz detection
- GRB 260831A: Fermi GBM Final Real-time Localization
- GRB 260829A: GECAM-B observation of a long burst
- GRB 260825A: SVOM/GRM observation of a long burst
- GRB 260825A: GECAM-B observation
- GRB 260829A: Fermi GBM Detection
- GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
- GRB 260829A: Fermi GBM Final Real-time Localization
- Fermi GBM trigger 809666623/260829141 is not a GRB
- GRB 260818B: Further EP-FXT observation
- 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 260827A: Fermi GBM Final Real-time Localization
- 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
- EP260822a: Global MASTER-Net observations report
- EP Alert 260820.31: Global MASTER-Net observations report
- 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 260825A: Fermi GBM Final Real-time Localization
- 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/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
- The EP-WXT trigger 01709287395 is likely a flaring star
- GRB260822B: Fermi GBM Final Localization
- GRB 260822A: GROWTH-India Telescope Upper Limits
- GRB 260822A: GOTO optical upper limit
- GRB 260822A: SVOM detection of a short burst
- GRB 260818B: SVOM/C-GFT optical upper limit
- EP260731a: SVOM/ECLAIRs detection through offline targeted search
- IceCube Alert 260821A: Global MASTER-Net observations report
- The EP-WXT trigger 01709286204 is likely a flaring star