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"3757 results found.
- GRB 200227A: Enhanced Swift-XRT position
- LIGO/Virgo S200224ca : No significant candidates in TAROT - FRAM - GRANDMA observations
- GRB 200227A: Swift detection of a burst
- LIGO/Virgo S200225q: no counterpart candidate in SVOM/GWAC observations
- GRB 200224B: DDOTI/OAN optical observations report
- LIGO/Virgo S200224ca: No counterpart candidates in KAIT observations
- Fermi trigger No 604231129: Global MASTER-Net observations report
- LIGO/Virgo S200224ca: Subaru/Hyper Suprime-Cam follow-up observations
- Fermi trigger No 604213554: 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.
- LIGO/Virgo S200219ac: No counterpart candidates in KAIT observations
- Fermi trigger No 603949983: Global MASTER-Net observations report
- LIGO/Virgo S200219ac: No transient candidates in CALET observations
- Fermi trigger No 603849435: Global MASTER-Net observations report
- GRB 200219A: Swift-XRT refined Analysis
- LIGO/Virgo S200219ac: Global MASTER-Net observations report
- GRB 200216B: second epoch optical upper limit at Mondy observatory
- GRB 200216B: Mondy and AbAO optical upper limits
- 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
- GRB 200216B: Swift-BAT refined analysis
- LIGO/Virgo S200213t : No significant candidates in FRAM - OAJ - TAROT - GRANDMA observations
- GRB 200216B - possible IR counterpart from VLT
- GRB 200216B: Enhanced Swift-XRT position
- GRB 200216B: Nanshan/NEXT early optical upper limit and possible host galaxy
- GRB 200216B: Swift detection of a burst
- LIGO/Virgo S200213t: No transient candidates in CALET observations
- LIGO/Virgo S200213t: No Counterparts from GECKO observation of host galaxy candidates in GW-neutrino detection overlap area
- LIGO/Virgo S200213t: No counterpart candidates in KAIT observations
- LIGO/Virgo S200208q : No significant candidates in TAROT - FRAM - GRANDMA observations
- LIGO/Virgo S200208q: no counterpart candidate in SVOM/C-GFT observations
- LIGO/Virgo trigger S200213t: Possible host galaxies
- ZTF20aajnksq: Upper limits from Konus-Wind observations
- LIGO/Virgo S200208q: No counterpart candidates in KAIT observations
- GRB 200211A: BALROG localization (Fermi Trigger 603098793 / GRB 200211310)
- GRB 200211A: Fermi GBM Final Real-time Localization
- LIGO/Virgo S200208q: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- Fermi trigger No 602817262: Global MASTER-Net observations report
- Swift GRB200205.81: Global MASTER-Net observations report
- Fermi trigger No 602455182: Global MASTER-Net observations report
- LIGO/Virgo S200128d: Upper limits from Konus-Wind observations
- GRB 200131A: ISON-Castelgrande optical observations
- GRB 200131A: VIRT optical transient detection
- LIGO/Virgo S200128d: no counterpart candidate in SVOM/GWAC observations
- LIGO/Virgo S200128d : No significant candidates in FRAM - TAROT - GRANDMA observations
- LIGO/Virgo S200128d: upper limits from AGILE/GRID observations
- LIGO/Virgo S200128d: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S200128d: Upper limits from CALET observations
- LIGO/Virgo S200128d: No counterpart candidates in KAIT observations
- Fermi-LAT ANTARES coincidence: IceCube neutrino search
- GRB 200128B: AGILE/MCAL detection of a burst
- Fermi-LAT-ANTARES coincidence
- LIGO/Virgo S200128d : no neutrino counterpart candidate in ANTARES search
- LIGO/Virgo S200128d: Coverage and upper limits from MAXI/GSC observations
- GRB 200128A: Fermi GBM Final Real-time Localization
- LIGO/Virgo S200128d: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo S200128d: Identification of a GW compact binary merger candidate
- LIGO/Virgo S200128d: Upper limits from IceCube neutrino searches
- LIGO/Virgo S200128d: Global MASTER-Net observations report
- Fermi trigger No 601729856: Global MASTER-Net observations report
- Fermi trigger No 601677816: Global MASTER-Net observations report
- Correction to GRB 200125A: Swift-XRT refined analysis
- LIGO/Virgo S200114f : No significant candidates in TAROT - FRAM - GRANDMA observations
- LIGO/Virgo S200115j: Zwicky Transient Facility search for optical counterparts to Swift X-ray sources
- Fermi trigger No 601363105: Global MASTER-Net observations report
- LIGO/Virgo S200115j : No significant candidates in TAROT - FRAM - GRANDMA observations
- GRB 200115A: Mondy optical observations and correction to GCN 26790
- LIGO/Virgo S200112r : No significant candidates in TAROT - FRAM - GRANDMA observations.
- Baksan Neutrino Observatory Alert 200116.22: Global MASTER-Net observations report
- IPN triangulation of GRB 200111A
- LIGO/Virgo S200115j: Candidates from the Zwicky Transient Facility
- LIGO/Virgo S200115j: INTEGRAL was inactive at the time of the event
- LIGO/Virgo S200112r: Upper limits from CALET observations
- LIGO/Virgo S200112r: upper limits from AGILE/GRID observations
- LIGO/Virgo S200105ae : No significant candidates in TAROT - FRAM - GRANDMA observations.
- Fermi trigger No 600227156: Global MASTER-Net observations report
- LIGO/Virgo S200105ae: Candidates from the Zwicky Transient Facility
- LIGO/Virgo S200105ae: Upper limits from CALET observations.
- GRB 200107B: Swift detection of a burst
- LIGO/Virgo S200105ae: Global MASTER-Net observations report
- Fermi trigger No 599954133: Global MASTER-Net observations report
- GRB 200105A: MAXI/GSC detection
- Fermi trigger No 599761015: Global MASTER-Net observations report
- IPN triangulation of GRB 200101A
- GRB 191228A: Early Optical Upper Limits from LCO
- IceCube Alert 200101.46: Global MASTER-Net observations report
- GRB 191228A: Mondy optical upper limit
- GRB 191228A: ePESSTO+ NTT optical upper limit
- GRB 191228A: UKIRT NIR upper limit
- LIGO/Virgo S191222n: No transient candidates in CALET observations
- Swift GRB191228.00: Global MASTER-Net observations report
- Swift GRB191227A: Global MASTER-Net OT detection
- Swift GRB191227.07: Global MASTER-Net observations report
- Swift GRB191226.02: Global MASTER-Net observations report
- LIGO/Virgo S191222n : No significant candidates in FRAM-TAROT-GRANDMA observations
- LIGO/Virgo S191222n: no counterpart candidate in SVOM/GWAC observations
- GRB 191221B: iTelescope optical observations
- LIGO/Virgo S191216ap: No significant candidates found in Pan-STARRS observations