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"28086 results found.
- GRB 230618A: Swift-XRT refined Analysis
- GRB 230616A: Swift-XRT observations
- LIGO/Virgo S230616aa: Global MASTER-Net observations report
- LIGO/Virgo S230615an: Global MASTER-Net observations report
- GRB230618A: LCOGT Optical Observations
- GRB 230618A: Swift detection of a burst
- LIGO/Virgo/KAGRA S230615az: T80S Search and Candidate Counterpart Identification
- GRB 230616A: Swift/BAT-GUANO detection of a short burst outside the coded FOV
- LIGO/Virgo/KAGRA S230615az: Xinglong-2.16m photometric observations of GIT candidates
- LIGO/Virgo/KAGRA S230529ay: Upper limits from a two-week IceCube neutrino search
- LIGO/Virgo/KAGRA S230615az: GROWTH-India candidates
- GRB 230614B: Fermi GBM Observation
- GRB 230614C: Fermi GBM Detection
- LIGO/Virgo S230613at: Global MASTER-Net observations report
- LIGO/Virgo S230614t: Global MASTER-Net observations report
- GRB 230614B: Swift/BAT-GUANO detection outside the coded FOV
- Fermi trigger No 708426906: Global MASTER-Net observations report
- GRB 230606A: LCOGT Optical Observations
- IceCube-Cascade 230610A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S230608as: Updated Sky localization
- LIGO/Virgo/KAGRA S230606d: Updated Sky localization
- LIGO/Virgo/KAGRA S230609u: Updated Sky localization
- LIGO/Virgo/KAGRA S230609u: Identification of a GW compact binary merger candidate
- LIGO/Virgo S230608as: Global MASTER-Net observations report
- ZTF23aamxeqf/AT2023jxk: 1.3m DFOT Optical upper limit
- LIGO/Virgo/KAGRA S230608as: Identification of a GW compact binary merger candidate
- Fermi GRB 230603A: Global MASTER-Net observations report
- Fermi trigger No 707039690: Global MASTER-Net observations report
- ZTF and GIT Observations of the Candidate Optical Afterglow AT2023jxk
- GRB 230606A: Swift-BAT refined analysis
- GRB 230606A: Gaoyazi/GOT optical upper limit
- GRB 230606A: Fermi GBM Observation
- GRB 230606A: Swift-XRT refined Analysis
- GRB 230604A: GRBAlpha detection
- GRB 230606A: Swift/UVOT Upper Limits
- GRB 230606A: Enhanced Swift-XRT position
- LIGO/Virgo/KAGRA S230606d: Identification of a GW compact binary merger candidate
- Fermi-LAT gamma-ray observations of IceCube-230603A
- LIGO/Virgo/KAGRA S230605o: Updated Sky localization
- IceCube-230603A: Upper limits from a search for additional neutrino events in IceCube
- LIGO/Virgo/KAGRA S230601bf: Updated Sky localization
- LIGO/Virgo/KAGRA S230605o: Identification of a GW compact binary merger candidate
- LIGO/Virgo S230602ap: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230518h: Upper limits from a two-week IceCube neutrino search
- GRB 230521A: VZLUSAT-2 detection
- GRB 230522A: GRBAlpha and VZLUSAT-2 joint detection
- LIGO/Virgo/KAGRA S230601bf: Identification of a GW compact binary merger candidate
- LIGO/Virgo/KAGRA S230529ay: AstroSat CZTI non-detection and upper limits
- LIGO/Virgo/KAGRA S230529ay: upper limits from AGILE/MCAL
- LIGO/Virgo/KAGRA S230529ay: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S230529ay: Upper limits from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S230529ay: Updated Sky localization and EM Bright Classification
- LIGO/Virgo/KAGRA S230529ay: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo/KAGRA S230529ay: Identification of a GW compact binary merger candidate
- Alert from the HAWC Burst Monitor HAWC-230527A
- LIGO/Virgo S230525a: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230518h: Updated Sky localization
- LIGO/Virgo/KAGRA S230520ae: Updated Sky localization
- Fermi-LAT gamma-ray observations of IceCube-230524A
- LIGO/Virgo/KAGRA S230518h: Upper limits from Glowbug gamma-ray observations
- GRB 230510A: Swift-BAT refined analysis
- GRB 230525A: Fermi GBM Detection
- LIGO/Virgo/KAGRA S230518h: TESS observations of the localization region
- IceCube-230524A: Upper limits from a search for additional neutrino events in IceCube
- GRB 230523B: GRBAlpha detection
- GRB 230524A: Fermi GBM Observation
- GRB 230523A: Swift/BAT-GUANO detection of a short hard burst
- LIGO/Virgo/KAGRA S230521k: Additional candidates from Zwicky Transient Facility
- LIGO/Virgo/KAGRA S230522n: Upper limits from IceCube neutrino search
- LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for MeerLICHT candidates: AT2023ixg and AT2023iyb
- LIGO/Virgo/KAGRA S230522a: 2 counterpart neutrino candidates from IceCube neutrino searches
- GRB 230518B: VZLUSAT-2 detection
- IPN triangulation of GRB 230518A (short)
- Fermi trigger No 706317104: Global MASTER-Net observations report
- LIGO/Virgo/KAGRA S230520ae: Identification of a GW compact binary merger candidate: End-to-End Test
- LIGO/Virgo/KAGRA S230520ae: Upper limits from IceCube neutrino search
- LIGO/Virgo/KAGRA S230518h: GECKO tiling observations with KMTNet
- LIGO/Virgo/KAGRA S230518h: Swift/UVOT Upper Limits for Swope candidates: SSS23a, SSS23b and SSS23c
- GRB 230520A: MAXI/GSC detection
- LIGO/Virgo/KAGRA S230518h: ATLAS observations of the skymap
- LIGO/Virgo/KAGRA S230518h: Swope Search and Candidate Counterpart Identification
- GRB 230518A: Fermi GBM Observation
- LIGO/Virgo/KAGRA S230518h: Upper limits from Konus-Wind observations
- LIGO/Virgo S230518h: AGILE/MCAL observations
- GRB 230518A: Swift/BAT-GUANO detection
- LIGO/Virgo S230518h: Swift XRT observations, 8 X-ray sources
- LIGO/Virgo/KAGRA S230518h: Coverage and upper limits from MAXI/GSC observations
- LIGO/Virgo/KAGRA S230518h: AstroSat CZTI non-detection and upper limits
- LIGO/Virgo/KAGRA S230518h: Upper limits from Fermi-GBM Observations
- LIGO/Virgo/KAGRA S230518h: Updated Sky localization and EM Bright Classification
- LIGO/Virgo S230518h: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- LIGO/Virgo S230518h: Upper limits from IceCube neutrino search
- LIGO/Virgo/KAGRA S230518h: Identification of a GW compact binary merger candidate
- GRB 230517A: BALROG localization (Fermi Trigger 706014351 / GRB 230517462)
- GRB 230510B: Fermi GBM detection
- IPN triangulation of GRB 230512A
- GRB 230512A: Nanshan/NEXT non-detection of GRB afterglow candidate
- GRB 230512A: GIT non detection of afterglow candidate
- GRB 230512A: Kitab possible afterglow candidate
- Fermi trigger No 705565670: Global MASTER-Net observations report