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"
10363 results found.
- Fermi trigger No 763509110: Global MASTER-Net observations report
- GRB 250312B: Fermi GBM Final Localization
- LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
- GRB 250312A: Swift detection of a burst
- GRB 230509B: 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
- GRB 250311A/EP250311a: TRT optical upper limit
- EP250311a/GRB 250311A: EP-WXT detection
- GRB 250311A/MAXI J1457-026: MAXI/GSC detection
- Konus-Wind detection of GRB 250309B
- IPN triangulation of GRB 250308A (short)
- IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
- GRB 250309B: Swift-XRT refined Analysis
- GRB 250309B / AT2025dws: Swift-UVOT detection
- Fermi GRB 250309A: Global MASTER-Net observations report
- Fermi-LAT gamma-ray observations of IceCube-250309A
- IceCube Alert 250309.32: Global MASTER-Net observations report
- EP250308a: Einstein Probe detection of an X-ray transient
- The EP-WXT trigger 01709132387 is likely a flaring star
- Fermi GRB 250307A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 250306A
- IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
- GRB 250305A: AstroSat CZTI detection
- GRB 250306A: AstroSat CZTI detection
- Fermi trigger No 762963055: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
- Fermi-LAT Gamma-ray Observations of IceCube-250302A
- EP 250304A: Optical counterpart detection by LCO
- EP250302A: 1.3m DFOT optical afterglow detection
- IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
- EP250304a: refined analysis of the EP-WXT and EP-FXT observations
- Konus-Wind detection of GRB 250222A
- EP250304a: Einstein Probe detection of an X-ray transient
- EP250302a: SAO RAS optical observations
- EP250302a : GIT optical follow-up
- EP250302a: optical observation from the INAF Asiago Observatory
- IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
- EP250302A: VLT near-infrared observations
- EP250302a: OHP/T193 optical and spectroscopic observations
- EP250302a: Einstein Probe detection of an X-ray transient
- EP250302a: Montarrenti Observatory optical detection
- Fermi GRB 250302A: Global MASTER-Net observations report
- EP250302a: FTW optical and NIR detection
- IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
- EP250228a: Optical observations with Kinder and Swift/UVOT
- Konus-Wind detection of GRB 250226A
- GRB 250225B: VLT/HAWKI near-infrared observations
- EP250227a: Einstein Probe detected of a fast X-ray transient
- EP250223a: J band upper limit by SYSU 80cm telescope
- EP250228a: Einstein Probe detection of an X-ray transient
- GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
- EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
- Konus-Wind detection of GRB 250225B
- GRB 250225B: VLT/FORS2 candidate optical afterglow
- EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
- EP250226a / GRB 250226A: TRT optical counterpart observation
- LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
- EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
- Fermi GRB 250226A: Global MASTER-Net observations report
- EP250225a: Einstein Probe detected of a fast X-ray transient
- Fermi GRB 250225A: Global MASTER-Net observations report
- EP250215A: J band upper limit by SYSU 80cm telescope
- LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
- GRB 250223C: Fermi GBM Final Real-time Localization
- GRB 250202B: VZLUSAT-2 detection
- GRB 250219A: EP-FXT afterglow detection
- EP250223a: 1.6m Mephisto and 50cm array observations
- 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: NOT optical afterglow candidate
- Fermi GRB 250223A: Global MASTER-Net observations report
- EP250223a: Einstein Probe detection of an X-ray transient
- LIGO/Virgo/KAGRA S250206dm: Upper limits from IceCube neutrino searches
- GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
- Konus-Wind detection of GRB 250221A
- GRB 250221A: Assy optical observations
- EP250220a: FTW optical and NIR observations and upper limits
- EP250220a: EP-FXT follow-up observations
- GRB 250221A: Swift-XRT refined Analysis
- EP250220a: Liverpool Telescope upper limits
- EP250220a: 1.6m Mephisto observations
- EP250220a: Liverpool Telescope optical upper limits
- GRB 250221A: Swift detection of a burst with an optical counterpart
- Swift GRB250221.15: Global MASTER-Net OT detection
- Swift GRB250221.15: Global MASTER-Net observations report
- Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
- GRB 250220B: Fermi GBM Final Real-time Localization
- Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
- GRB 250220A: Fermi GBM Final Real-time Localization
- EP250220a: Global MASTER-Net observations report
- EP250220a: EP-WXT detection of a fast X-ray transient
- Konus-Wind detection of GRB 250217C (short)
- GRB 250219A: OHP/T193 optical upper limit
- GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
- Konus-Wind detection of GRB 250215A / EP250215a