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"4055 results found.
- LIGO/Virgo S200302c: Updated Sky Localization
- LIGO/Virgo S200302c: No significant counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S200302c: No counterpart candidates in KAIT observations
- LIGO/Virgo S200302c: no counterpart candidates in the Swift/BAT observations
- LIGO/Virgo S200224ca: Transient found in Swift/UVOT counterpart search
- LIGO/Virgo S200302c: No counterpart candidates in HAWC observations
- LIGO/Virgo S200302c: Upper limits from Fermi-GBM Observations
- LIGO/Virgo S200302c: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- LIGO/Virgo S200302c : no neutrino counterpart candidate in ANTARES search
- LIGO/Virgo S200302c: upper limits from AGILE/MCAL observations
- LIGO/Virgo S200225q: AstroSat CZTI upper limits
- LIGO/Virgo S200219ac: AstroSat CZTI upper limits
- LIGO/Virgo S200302c: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo S200302c: Upper limits from IceCube neutrino searches
- LIGO/Virgo S200302c: Identification of a GW compact binary merger candidate
- LIGO/Virgo S200302c: Global MASTER-Net observations report
- LIGO/Virgo S200225q : No significant candidates in TAROT - FRAM - GRANDMA observations.
- LIGO/Virgo S200224ca: Updated Sky Localization and EM Bright Classification
- LIGO/Virgo S200213t: No significant EM counterparts identified from continued GECKO observation of host galaxy candidates
- IceCube-200227A : Upper limits from Insight-HXMT/HE observations
- LIGO/Virgo S200224ca : No significant candidates in TAROT - FRAM - GRANDMA observations
- LIGO/Virgo S200225q: Not observable by CALET
- LIGO/Virgo S200224ca: Upper limits from CALET observations.
- LIGO/Virgo S200224car: GRAWITA VST-ESO PARANAL observations.
- LIGO/Virgo S200225q: Updated Sky Localization
- LIGO/Virgo S200224ca: DESGW Optical counterpart candidates from DECam
- LIGO/Virgo S200219ac: Upper limits from Konus-Wind observations
- LIGO/Virgo S200213t: Upper limits from Konus-Wind observations
- LIGO/Virgo S200208q: Upper limits from Konus-Wind observations
- LIGO/Virgo S200225q: no counterpart candidate in SVOM/GWAC observations
- LIGO/Virgo S200225q: Upper limits from Insight-HXMT/HE observations
- LIGO/Virgo S200224ca: Upper limits from Insight-HXMT/HE observations
- LIGO/Virgo S200225q: no counterpart candidates in the Swift/BAT observations
- LIGO/Virgo S200224ca: no counterpart candidates in the Swift/BAT observations
- LIGO/Virgo S200219ac: Updated Sky Localization
- LIGO/Virgo S200224ca: No counterpart candidates in KAIT observations
- LIGO/Virgo S200224ca: No Counterparts in DDOTI/OAN Optical Observations
- LIGO/Virgo S200224ca: GRAWITA-Campo Imperatore observations.
- LIGO/Virgo S200225q: Upper limits from Fermi-GBM Observations
- LIGO/Virgo S200225q: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S200225q: upper limits from AGILE/GRID observations
- LIGO/Virgo S200224ca: Subaru/Hyper Suprime-Cam follow-up observations
- LIGO/Virgo S200225q: upper limits from AGILE/MCAL observations
- LIGO/Virgo S200225q: Upper limits from IceCube neutrino searches
- LIGO/Virgo S200225q: No counterpart candidates in HAWC observations
- LIGO/Virgo S200225q : no neutrino counterpart candidate in ANTARES search
- LIGO/Virgo S200225q: Global MASTER-Net observations report
- LIGO/Virgo S200224ca: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S200225q: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- LIGO/Virgo S200225q: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo S200219ac: No counterpart candidates from Nanshan/NEXT observations
- LIGO/Virgo S200224ca: upper limits from AGILE/GRID observations
- LIGO/Virgo S200225q: Identification of a GW compact binary merger candidate The LIGO Scientific Collaboration and the Virgo Collaboration
- LIGO/Virgo S200224ca: not observable by Fermi-GBM
- LIGO/Virgo S200224ca: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo S200224ca: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo S200224ca: upper limits from AGILE/MCAL observations
- LIGO/Virgo S200224ca: Global MASTER-Net observations report
- LIGO/Virgo S200224ca: Upper limits from IceCube neutrino searches
- LIGO/Virgo S200224ca: Identification of a GW compact binary merger candidate The LIGO Scientific Collaboration and the Virgo Collaboration
- GRB 200224A: Swift-XRT refined Analysis
- GRB 200224C: Fermi GBM Final Real-time Localization
- GRB 200224A: Tautenburg observations
- GRB 200224A: BOOTES-1 and 1.5m OSN optical observations
- Fermi trigger No 604213554: Global MASTER-Net observations report
- GRB 200224B: Fermi GBM Final Real-time Localization
- GRB 200224A: Swift detection of a burst
- Swift GRB200224.14: Global MASTER-Net observations report
- LIGO/Virgo S200219ac: no counterpart candidate in SVOM/GWAC-F30 observations
- LIGO/Virgo S200219ac: no counterpart candidate in SVOM/GWAC observations
- LIGO/Virgo S200219ac : No significant candidates in TAROT - FRAM - GRANDMA observations.
- IPN triangulation of GRB 200219B (inconsistent with the LIGO/Virgo S200219ac)
- LIGO/Virgo S200219ac: No counterpart candidates in KAIT observations
- LIGO/Virgo S200213t: AT2020clw/ZTF20aanaoyz, AT2020crd/ZTF20aanakge and AT2020cly/ZTF20aanakes 10.4m GTC spectroscopy
- LIGO/Virgo S200213t: Swift UVOT and XRT observations of ZTF20aamvmzj (AT2020cja)
- LIGO/Virgo S200219ac: No transient candidates in CALET observations
- LIGO/Virgo S200219ac: no counterpart candidates in the Swift/BAT observations
- LIGO/Virgo S200219ac: Fermi GBM transient event not confidently associated with GW signal
- LIGO/Virgo S200219ac: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S200219ac: upper limits from AGILE/GRID observations
- LIGO/Virgo S200213t: Keck/LRIS spectroscopy of counterpart candidates from the Zwicky Transient Facility
- LIGO/Virgo S200219ac: upper limits from AGILE/MCAL observations
- LIGO/Virgo S200219ac : no neutrino counterpart candidate in ANTARES search
- LIGO/Virgo S200219ac: Upper limits from IceCube neutrino searches
- LIGO/Virgo S200219ac: No counterpart candidates in HAWC observations
- LIGO/Virgo S200219ac: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo S200219ac: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- LIGO/Virgo S200219ac: Identification of a GW compact binary merger candidate
- LIGO/Virgo S200219ac: Global MASTER-Net observations report
- LIGO/Virgo (S200213t/IceCube neutrino candidate: No counterpart candidates in the Swift-XRT Observations
- LIGO/Virgo S200213t: No EM counterparts found from continued GECKO observation of host galaxy candidates
- LIGO/Virgo S200213t: APO Upper Limits for ZTF20aanakes/AT2020cly
- LIGO/Virgo S200213t : No significant candidates in FRAM - OAJ - TAROT - GRANDMA observations
- LIGO/Virgo S200213t: AstroSat CZTI upper limits
- LIGO/Virgo S200213t: Updated Sky Localization
- LIGO/Virgo S200213t: Updated coverage and candidate list for the Zwicky Transient Facility
- LIGO/Virgo S200213t: CLU/NED Galaxies in the 4-Update Localization Volume
- LIGO/Virgo S200213t: Possible host galaxies in the bilby skymap
- LIGO/Virgo S200213t: Updated Sky Localization
- LIGO/Virgo S200213t: Pre-discovery detections of MASTER OT J044008.76-651302.3