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.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
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"32531 results found.
- GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
- GRB 250702F: GRANDMA observations
- GRB 250706B: refined SVOM/MXT data analysis
- GRB 250706A: Swift/UVOT Upper Limits
- GRB 250706B: REM optical observations
- GRB 250706A: REM optical/NIR observations
- EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
- IceCube-250416A: DDOTI Optical Upper Limit
- IceCube-250706A: COLIBRÍ optical upper limits
- Swift GRB 250706A: Global MASTER-Net observations report
- GRB 250706A: JinShan optical upper limits
- GRB 250706A: SAO RAS optical observations
- EP250704A: NOWT Detection
- GRB 250706A: SVOM/C-GFT upper limit in eary phase
- GRB250706B: Swift-XRT counterpart detection
- GRB 250706B: iTelescope optical observations
- EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
- GRB 250706B: SVOM/VT optical observation
- GRB 250706B: TRT bright optical counterpart detection
- GRB 250706A: GROWTH-India Telescope optical upper limit
- GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
- EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
- GRB 250703A: EIRSAT-1 GMOD Detection
- EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
- GRB 250704B: Swift/UVOT Upper Limits
- GRB 250704A: Swift/UVOT Detection
- LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
- Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
- GRB 250704B: Insight-HXMT detection
- Konus-Wind detection of GRB 250703A
- IPN triangulation of GRB 250703A
- EP250704a/GRB 250704B: GSP observations of the optical counterpart
- EP250704a/GRB 250704B: FTW optical and NIR observations of the counterpart
- GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
- Konus-Wind detection of short/hard GRB 250704B/ EP250704a
- EP250704a / GRB 250704B: NOT observations of the optical afterglow
- EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
- GRB 250702F: Kilonova-Catcher optical afterglow detection
- GRB 250702F: Monte Agliale Observatory optical observations
- GRB250702F: afterglow detected by joint EP-ZTF shadowing program
- EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
- EP250704a / GRB 250704B: JinShan optical observations
- GRB 250704A: SVOM/VT optical observation
- EP250704a / GRB 250704B: SAO RAS optical observations
- EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
- GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
- EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
- EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
- EP 250704a: BOOTES-5 optical detection
- EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
- LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
- GRB 250702A: Insight-HXMT detection
- GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
- GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
- EP250704a / GRB250704B: Swift-XRT counterpart detection
- GRB 250704A: Swift-XRT afterglow detection
- GRB 250702B / EP2050702a: FTW optical and NIR observations
- Konus-Wind detection of GRB 250702F
- EP250704a / GRB 250704B - REM observations
- GRB 250702F: GROWTH-India Telescope optical observations
- EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
- GRB 250704A: REM retraction of optical afterglow detection and updated limit
- EP250702a: WFST optical observations
- EP250704a: COLIBRÍ optical counterpart candidate
- EP250704a: Einstein Probe detection of an X-ray transient
- GRB 250702F: optical photometry from Konkoly
- GRB 250704A: REM detection of the optical afterglow
- LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
- GRB 250702F: SVOM/VT optical observation
- LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
- GRB 250702F: Swift/UVOT Detection
- GRB 250702A: CALET Gamma-Ray Burst Monitor detection
- Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
- Fermi GRB 250703A: Global MASTER-Net observations report
- GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
- GRB 250702F: Fermi GBM Observation
- GRB 250702F: Leavitt Observatory optical observations
- GRB 250702F: AKO Optical Afterglow Detection
- GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
- GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
- GRB 250702A: GECAM-B detection
- GRB 250702F: Skynet Optical Observations
- GRB 250424A: VIRT Optical Upper Limit
- GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
- GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
- EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
- GRB 250702F: TRT Optical Observation
- GRB 250703A: DDOTI Optical Upper Limit
- GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
- GRB 250702F: REM optical afterglow detection
- EP250702a: Global MASTER-Net observations report
- GRB 250702F: DDOTI Optical Observation
- GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
- GRB 250702F: COLIBRÍ Observations of the Afterglow
- EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
- Fermi GRB 250702E: Global MASTER-Net observations report
- Fermi GRB 250702B: Global MASTER-Net observations report
- GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
- GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
- GRB 250702F: NOT observations of the optical afterglow