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.
Lucene Examples (click to copy):
subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
23217 results found.
- EP250215A: J band upper limit by SYSU 80cm telescope
- LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
- LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
- EP250223a: Kinder optical follow-up observations
- LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
- 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
- GRB 250222A: SVOM/GRM observation of a burst
- 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: refined analysis of the EP-WXT and FXT observations
- 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
- The EP-WXT trigger 01709131882 is likely a flaring star
- EP250223a: OASDG optical observations
- EP250223a: Swift/XRT localization
- EP250223a: NOT optical afterglow candidate
- EP250223a: Einstein Probe detection of an X-ray transient
- LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
- GRB 250221A: Optical counterpart detection by LCO.
- Konus-Wind detection of GRB 250221A
- EP250220a: EP-FXT follow-up observations
- GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
- GRB 250221A: GRANDMA/TAROT Detection
- GRB 250221A: Swift-XRT refined Analysis
- GRB 250221A: 1.6m Mephisto optical detection
- GRB 250221A: AKO Optical Upper Limit
- GRB 250221A: Swift/UVOT Detection
- EP250220a: Liverpool Telescope upper limits
- GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
- GRB 250221A: REM optical/NIR afterglow detection
- GRB 250221A: Enhanced Swift-XRT position
- EP250220a: 1.6m Mephisto observations
- EP250220a: Liverpool Telescope optical upper limits
- 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
- EP250220a: EP-WXT detection of a fast X-ray transient
- GRB 250219A: Swift/UVOT Upper Limits
- GRB 250219A: OHP/T193 optical upper limit
- GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
- GRB 250219A: 1.6m Mephisto optical upper limits
- GRB 250219A: Swift-XRT observations
- LIGO/Virgo/KAGRA S250206dm: Upper limits from MSU cubesats observations
- GRB 250219A: SVOM detection of a burst
- SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
- GRB 250217C: Swift-XRT observations
- SVOM/sb25021804: QSO variability in Liverpool Telescope 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
- 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
- IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
- GRANDMA/OPD observations of GRB250215A
- The EP-WXT trigger 01709131775 is likely a flaring star
- GRB 250215A / EP250215a: LCO detection of the afterglow
- GRB 250215A: Swift/UVOT Upper Limits
- GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
- EP250215a / GRB 250215A : GTC redshift z = 4.61
- GRB 250215A: Fermi GBM Observation
- GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
- GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
- GRB 250215A: Swift-XRT refined Analysis
- GRB 250215A: SVOM/GRM observation
- EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
- EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
- EP250207b: Xinglong optical upper limit
- EP250212a: Xinglong optical upper limit
- LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
- GRB 250213A: SVOM detection of a burst
- GRB 250205A: VIRT Optical Upper Limit
- GRB 250205A: Leavitt Observatory optical upper limit
- EP250207B: Chandra localization of the X-ray counterpart
- EP250212a: Liverpool Telescope optical upper limits
- EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
- GRB250101A: Radio upper limits from GMRT observations
- EP trigger 10202399251 (possibly EP250212a): NOT J-band upper limit
- EP250207B: GTC z-band Observations
- LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
- GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
- EP250207b: NOT optical counterpart candidate
- GRB 250211B: A long GRB detected by INTEGRAL
- LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
- Integral GRB250211.89: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
- GRB 250207A: Fermi GBM Observation
- GRB 250206A: Fermi GBM Observation
- GRB 250205A / EP250205A: radio detection with the VLA