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"
3363 results found.
- EP250428b: Global MASTER-Net observations report
- GRB 250424A: Swift-BAT refined analysis
- IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
- GRB 250424A: BlackGEM optical afterglow detection
- IceCube Alert 250421.71: Global MASTER-Net observations report
- GRB 250419A: LCO optical observation
- GRB 250419A: AKO Optical Afterglow Detection
- SVOM/sb25041603 is not a GRB
- EP250404a: Nanshan 0.43m Telescope optical observatios
- Fermi trigger No 766173972: Global MASTER-Net observations report
- Fermi GRB 250407A: Global MASTER-Net observations report
- IceCube Alert 250406.95: Global MASTER-Net observations report
- EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
- GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
- Fermi GRB 250404A: Global MASTER-Net observations report
- GRB 250403A: Montarrenti Observatory optical detection
- EP250404a: Global MASTER-Net observations report
- GRB 250402A: Fermi GBM Observation
- Fermi GRB 250331E: Global MASTER-Net observations report
- GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
- LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
- GRB 250331A: MAXI/GSC detection
- Fermi GRB 250330B: Global MASTER-Net observations report
- IceCube Alert 250330.35: Global MASTER-Net observations report
- GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
- GRB 250327B: LCO optical counterpart detection
- IPN triangulation of GRB 250322B
- FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
- FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
- EP250321a: Kinder optical follow-up observations
- Fermi GRB 250320B: Global MASTER-Net observations report
- EP250321a: BOOTES-5/JGT optical afterglow detection
- EP250321a: TRT optical counterpart detection
- Swift GRB 250321A: Global MASTER-Net observations report
- GRB 250309B/AT2025dws: further ATCA observations
- GRB 250316A: Fermi GBM Final Real-time Localization
- GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
- EP250311a/GRB 250311A: Correction to EP-WXT detection time
- Fermi GRB 250313A: Global MASTER-Net observations report
- EP250311a/GRB 250311A: EP-FXT follow-up observation
- Fermi GRB 250312B: Global MASTER-Net observations report
- GRB 250312B: Fermi GBM Final Localization
- GRB 241228A: VIRT Optical Upper Limit
- GRB 250311A: Swift-XRT observations
- GRB 250311A/EP250311a: TRT optical upper limit
- GRB 250311A: Tiled Swift observations
- EP250311a/GRB 250311A: EP-WXT detection
- GRB 250311A/MAXI J1457-026: MAXI/GSC detection
- IceCube Alert 250309.32: Global MASTER-Net observations report
- EP250308a: Global MASTER-Net observations report
- EP250308a: Einstein Probe detection of an X-ray transient
- GRB 250307A: Fermi GBM Final Real-time Localization
- GRB 250306A: Swift-BAT refined analysis
- GRB 250305A: AstroSat CZTI detection
- Fermi trigger No 762963055: Global MASTER-Net observations report
- GRB 250305A: Fermi GBM Final Real-time Localization
- LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
- EP250302a: Montarrenti Observatory optical detection
- Fermi GRB 250302A: Global MASTER-Net observations report
- EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
- EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
- EP250226a / GRB 250226A: TRT optical counterpart observation
- GRB 250226A: Fermi GBM Final Real-time Localization
- Fermi GRB 250225A: Global MASTER-Net observations report
- GRB 250202B: VZLUSAT-2 detection
- EP250220a: EP-FXT follow-up observations
- EP250220a: 1.6m Mephisto observations
- SVOM trigger sb25022102 is not an astrophysical event
- SVOM/sb25022102: SVOM detection of an X-ray transient
- GRB 250221A: Swift detection of a burst with an optical counterpart
- Swift GRB250221.15: Global MASTER-Net observations report
- IceCube-Cascade 250215A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
- Fermi GRB 250217A: Global MASTER-Net observations report
- EP250215a: Global MASTER-Net observations report
- Fermi GRB 250212A: Global MASTER-Net observations report
- Fermi trigger No 760945500: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
- LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
- EP250207b: Global MASTER-Net observations report
- GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
- LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
- IceCube Alert 250207.09: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
- GRB 250207B: Swift-XRT observations
- GRB 250207B: Tiled Swift observations
- LIGO/Virgo/KAGRA S250206dm: SOAR galaxy targeted observations
- GRB 250207B: MAXI/GSC detection
- LIGO/Virgo/KAGRA S250206dm: Updated-6 NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S250206dm: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S250206dm: Updated NED Galaxies in the Localization Volume
- LIGO/Virgo/KAGRA S250206dm: NED Galaxies in the Localization Volume
- Konus-Wind detection of GRB 250202B
- IPN triangulation of GRB 250202B
- GRB 250202B: NuSTAR detection of the prompt emission
- GRB 250202B: Fermi GBM Detection
- GRB 250202B: AstroSat CZTI detection of a bright long GRB
- GRB 250202B: Fermi GBM Final Real-time Localization
- GRB 250129A: 1.3m DFOT Optical observations
- LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations