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"23577 results found.
- GRB 250221A: Swift-BAT refined analysis
- EP250223a: Kinder optical follow-up observations
- LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
- GRB 250119B: VZLUSAT-2 detection
- GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
- GRB 250202B: VZLUSAT-2 detection
- GRB 250219A: EP-FXT afterglow detection
- EP250223a: GOTO optical afterglow detections
- EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
- GRB 250210A: VZLUSAT-2 detection
- GRB 250206A: VZLUSAT-2 detection
- EP250223a: REM NIR upper limit
- EP250223a: TRT optical afterglow observation
- EP250223a: 1.6m Mephisto and 50cm array observations
- LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
- LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO trigger with ID 762004910: Identification of a GW compact binary merger candidate possibly associated with a sub-threshold Swift/BAT-GUANO trigger
- EP250223a: OASDG optical observations
- EP250223a: LCO detection of the afterglow
- EP250223a: early optical detection by BOOTES-4
- LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
- GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
- GRB 250221A: Optical counterpart detection by LCO.
- Konus-Wind detection of GRB 250221A
- GRB 250221A: Assy optical observations
- GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
- GRB 250221A: GRANDMA/TAROT Detection
- GRB 250221A: Swift-XRT refined Analysis
- GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
- GRB 250221A: REM optical/NIR afterglow detection
- EP250220a: 1.6m Mephisto observations
- EP250220a: Optical upper limit with Kinder observations
- SVOM trigger sb25022102 is not an astrophysical event
- SVOM/sb25022102: SVOM detection of an X-ray transient
- GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
- GRB 250221A: Swift detection of a burst with an optical counterpart
- EP250220a: Xinglong optical upper limit
- Konus-Wind detection of GRB 250217C (short)
- GRB 250219A: OHP/T193 optical upper limit
- GRB 250219A: NOT optical observations
- GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
- GRB 250219A: 1.6m Mephisto optical upper limits
- GRB 250219A: SVOM/VT optical counterpart
- GRB 250219A: Swift-XRT observations
- GRB 250219A: SVOM detection of a burst
- Konus-Wind detection of GRB 250215A / EP250215a
- SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
- GRB 250217C: Swift-XRT observations
- GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
- GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
- GRB 250217C: SVOM/GRM observation
- GRB 250217C: Fermi GBM Observation
- IPN triangulation of GRB 250217C (short)
- Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
- SVOM/sb25021804: SVOM detection of a long X-ray transient
- GRB 250213A: Swift-XRT observations
- GRB 250216A: AstroSat CZTI detection
- GRB 250217C: AstroSat CZTI detection of a short burst
- GRANDMA/OPD observations of GRB250215A
- GRB 250215A / EP250215a: LCO detection of the afterglow
- GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
- EP250215a / GRB 250215A : GTC redshift z = 4.61
- EP250215a / GRB 250215A : NOT optical observations
- GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
- LIGO/Virgo/KAGRA S250206dm: MASTER LC AT2025bbo
- GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
- GRB 250215A: Swift-XRT refined Analysis
- GRB 250215A: SVOM/GRM observation
- EP250215a / GRB 250215A: AstroSat CZTI detection
- EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
- EP250207b: Xinglong optical upper limit
- EP250212a: Xinglong optical upper limit
- GRB 250210A: GRBAlpha detection
- EP250207b: VLA radio upper limits
- EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
- EP250207B: GTC z-band Observations
- LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
- EP250207b: NOT optical counterpart candidate
- GRB 250211A: SVOM trigger sb25021103 is not a GRB
- LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
- LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
- GRB 250205A / EP250205A: radio detection with the VLA
- IceCube-250207A: One candidate from the Zwicky Transient Facility
- LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
- Konus-Wind detection of GRB 250207A
- Konus-Wind detection of GRB 250206A
- Fermi Gamma-ray Burst Monitor trigger 760945500/250211240 is not a GRB
- LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
- GRB 250207A: Skynet optical afterglow observations
- LIGO/Virgo/KAGRA S250206dm: Gemini-North spectroscopic observation of AT2025bbo and its host galaxy
- EP250207b: Gemini GMOS-N z-band observations
- EP250207A: Upper limits from Fermi-GBM Observations
- GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
- Fermi GRB 250210A: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
- GRB 250204B: GRBAlpha detection
- GRB 250204A: GRBAlpha detection
- LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder