GCN Circulars
GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"27831 results found.
- GRB 250312A: Swift-XRT refined Analysis
- GRB 250312A: Enhanced Swift-XRT position
- GRB 250312B: Fermi GBM Final Localization
- LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
- GRB 250226B: Fermi GBM Observation
- Swift GRB 250312A: Global MASTER-Net observations report
- GRB 250302A: Fermi GBM Observation
- GRB 250312A: Swift detection of a burst
- GRB 241213A: VIRT Optical Upper Limit
- GRB 241228A: VIRT Optical Upper Limit
- GRB 250311A/EP250311a: Optical upper limits with Kinder observations
- GRB 250223B: Fermi GBM Observation
- GRB 250311A: Swift-XRT observations
- GRB 250228A: Fermi GBM Observation
- GRB 250309B: 1.3m DFOT Optical observations
- GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
- GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
- GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
- GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
- GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
- GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
- GRB 250309B: PRIME near-infrared detection
- EP250304a: Chandra detection
- GRB 250225B: Swift-BAT refined analysis
- GRB 250311A: Tiled Swift observations
- EP250311a/GRB 250311A: EP-WXT detection
- GRB 250308A: CALET Gamma-Ray Burst Monitor detection
- GRB 250311B: SVOM detection of a burst
- GRB 250311A/MAXI J1457-026: MAXI/GSC detection
- IceCube-250309A: Upper limits from Fermi-GBM Observations
- Konus-Wind detection of GRB 250309B
- IPN triangulation of GRB 250308A (short)
- IPN triangulation of GRB 250309B
- IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
- GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
- GRB 250309B: Swift-XRT refined Analysis
- GRB 250309B / AT2025dws: Swift-UVOT detection
- GRB250309B: One candidate counterpart from the Zwicky Transient Facility
- IceCube-250309A: No candidates from the Zwicky Transient Facility
- Fermi-LAT gamma-ray observations of IceCube-250309A
- GRB 250308A: SVOM/GRM detection of QPO in the tail emission
- GRB 250309B: Fermi GBM Final Localization
- Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
- GRB 230509B: Tiled Swift observations
- IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
- EP250308a: GSP optical upper limit
- EP250308a: Einstein Probe detection of an X-ray transient
- GRB 250309A: Fermi GBM Final Real-time Localization
- GRB 250306A: EIRSAT-1 GMOD detection
- Konus-Wind detection of GRB 250306A
- GRB 250307A: Fermi GBM Final Real-time Localization
- GRB 250306A: Swift-BAT refined analysis
- GRB 250306A: NuSTAR detection of the prompt emission
- EP250304a: MeerKAT detection of a possible radio counterpart
- GRB 250305A: AstroSat CZTI detection
- GRB 250306A: AstroSat CZTI detection
- Swift GRB 250306A: Global MASTER-Net observations report
- GRB 250306A: Swift detection of a burst
- LIGO/Virgo/KAGRA S250306ej: Retraction of GW compact binary merger candidate
- GRB 250305A: Fermi GBM Final Real-time Localization
- EP 250304A: Optical counterpart detection by LCO
- EP250302A: 1.3m DFOT optical afterglow detection
- Konus-Wind detection of GRB 250222A
- IPN triangulation of GRB 250222A
- EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
- EP250304a: Swift-XRT detection of a fading X-ray source
- EP250304a: TRT optical counterpart detection
- EP250304a: Einstein Probe detection of an X-ray transient
- LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
- EP250225a: the candidate optical counterpart is an AGN
- EP250302a: Swift/UVOT detection
- EP250302a: Swift-XRT observations of a fading X-ray source
- EP250302a: Einstein Probe detection of an X-ray transient
- EP250302a: Montarrenti Observatory optical detection
- EP250302a: FTW optical and NIR detection
- EP250302a: Nanshan/HMT optical counterpart detection
- IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
- GRB 250302A: Fermi GBM Final Real-time Localization
- GRB 250228A: Fermi GBM Final Localization
- EP250228a: Optical observations with Kinder and Swift/UVOT
- Konus-Wind detection of GRB 250226A
- GRB 250225B: EIRSAT-1 GMOD Detection
- GRB 250225B: VLT/HAWKI near-infrared observations
- EP250227a: Optical upper limits with Kinder observations
- EP250227a: Einstein Probe detected of a fast X-ray transient
- EP250228a: updates on the EP observations
- EP250225a: EP-FXT follow-up observation
- EP250228a: Swift/XRT localisation
- EP250228a: Einstein Probe detection of an X-ray transient
- GRB 250226A / EP250226a: LCO detection of the afterglow
- GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
- EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
- GRB 250225B: INTEGRAL SPI-ACS detection
- EP250225a: TRT optical upper limits
- LIGO/Virgo/KAGRA S250206dm: Upper limits from SVOM/GRM Observations
- LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
- LIGO/Virgo/KAGRA S250227y: Retraction of GW compact binary merger candidate
- GRB 250226B: Fermi GBM Final Real-time Localization
- GRB 250225B: Fermi GBM Observation
- GRB 250221A: ATCA Detections and Upper Limits