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"3316 results found.
- EP260116a: COLIBRÍ detection of a fading optical source
- EP260119a: Global MASTER-Net observations report
- EP260119a: COLIBRÍ optical counterpart candidate
- EP260119a: preliminary result from the EP-FXT observation
- EP260119a: EP-WXT detection of a fast X-ray transient
- GRB 260117A: SVOM/VT optical candidate
- GRB 260117A: SVOM/C-GFT upper limit
- EP 260116a: COLIBRÍ optical upper limit
- EP260116a: Liverpool Telescope upper limits
- EP260116A: 1.3m DFOT optical upper limit
- EP260116a: Global MASTER-Net observations report
- EP260116a: Xinglong optical upper limit
- EP260116a: Einstein Probe detection of an X-ray transient
- Konus-Wind detection of GRB 260114A
- Konus-Wind detection of GRB 251230A / EP251230a
- EP-WXT trigger 01709251266: SVOM/C-GFT confirmation of a stellar flare
- EP260110a: NOT and GTC Optical and Near-Infrared Observations
- EP260110a: TRT optical upper limits
- Konus-Wind detection of GRB 260101A
- The EP-WXT trigger 01709251266 is likely a flaring star
- EP260110a: SVOM/VT optical upper limits
- EP260110a: Global MASTER-Net observations report
- EP260110a: KAIT optical upper limit
- EP260110a: refined analysis of the EP-WXT and EP-FXT observations
- EP 260110a: COLIBRÍ optical observations
- EP260110a: SVOM/C-GFT upper limit
- EP260110a: BOOTES-5/JGU optical upper limit
- EP260110a: Einstein Probe detection of an X-ray transient
- EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
- EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709251112 is likely a flaring star
- EP260105a: FTW optical observations
- The EP-WXT trigger 01709251028 is likely a flaring star
- EP260105a: SVOM/VT optical upperlimit
- EP260105a: refined analysis of the EP-WXT and EP-FXT observations
- EP260105a: LCO Optical Upper limit
- EP260104a: Global MASTER-Net observations report
- EP260104a: Einstein Probe detection of a fast X-ray transient
- EP260105a: Global MASTER-Net observations report
- EP260105a: Einstein Probe detection of an X-ray transient
- GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
- GRB 260102A: EP-FXT follow-up observation
- EP260101a: Global MASTER-Net observations report
- GRB 251230A / EP251230a: GECAM-B detection
- GRB 251230A / EP251230a: Insight-HXMT/HE detection
- EP260101a: refined analysis of the EP-WXT and EP-FXT observations
- EP260101a: Einstein Probe detection of an X-ray transient
- GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
- EP251229a: Optical upper limit with Kinder observations
- EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
- EP251229a: BOOTES-2 early optical upper limit
- EP251229a: NOT optical upper limits
- GRB 251230A / EP251230a: SVOM/VT optical observation
- EP251229a: refined analysis of the EP-WXT and EP-FXT observations
- EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
- EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
- GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
- The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
- EP251229a: Global MASTER-Net observations report
- EP251229a: Einstein Probe detection of an X-ray transient
- GRB 251222A/EP251222b: 1.6m Mephisto optical followup
- The EP-WXT trigger 01709250662 is likely a flaring star
- The EP-WXT trigger 01709250617 is likely a flaring star
- EP251222a: Optical upper limit with Kinder observations
- EP251220a: 3.6m DOT optical afterglow detection
- GRB 251222A: Fermi GBM Observation
- EP251220a: CrAO ZTSh optical observations
- EP251221a: PRIME upper limit
- EP251222a: Global MASTER-Net observations report
- EP251221a: Liverpool Telescope upper limits
- EP251222a: refined analysis of the EP-WXT and EP-FXT observations
- EP251222b/GRB 251222A: refined analysis of the EP-WXT and EP-FXT observations
- Konus-Wind detection of GRB 251222A / EP251222b
- GRB 251222A / EP251222b: LCO detection of the optical counterpart
- EP251222a: NTT/ULTRACAM optical observations
- EP251222a: GOTO optical upper limit
- GRB 251222A / EP251222b: GOTO optical counterpart detection
- EP251222a: GSP Optical Counterpart Detection
- GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
- EP251222b/GRB 251222A: SVOM/GRM observation
- EP251222b/GRB 251222A: Einstein Probe detection of an X-ray transient
- EP251222a: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709250397 is likely a flaring star
- EP251221a: Global MASTER-Net observations report
- EP251221a: NOT optical upper limit
- EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
- EP251220a: NOT optical observations
- EP251221a: Einstein Probe detection of a fast X-ray transient
- EP251220a: EP-FXT follow-up observation
- EP 251220a: GOTO optical counterpart detection
- EP 251220a: COLIBRÍ detection of the optical counterpart
- EP251220a: Global MASTER-Net observations report
- EP251220a: EP detection of a fast X-ray transient
- EP251214b: KAIT optical upper limit
- EP251214a: Optical upper limit with Kinder observations
- EP251214b: Global MASTER-Net observations report
- EP251214b : Einstein Probe detection of a fast X-ray transient
- EP251214b : Einstein Probe detection of a fast X-ray transient
- EP251214b (EP trigger 01709250023): LCO optical limits
- EP251214a: KAIT optical upper limit