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"
6098 results found.
- IceCube-200530A: No significant detection in HAWC
- IceCube-200530A: Candidate Counterparts from the Zwicky Transient Facility
- IceCube-200530A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- GRB 200529A: Swift-XRT refined Analysis
- GRB 200529A: Fermi GBM Detection
- GRB 200528A: Swift-XRT refined Analysis
- GRB 200529A: NOT optical afterglow
- GRB 200528A: Fermi GBM Observation
- Fermi-LAT Gamma-ray Observations of IceCube-190523A
- GRB200521A: ASIM observation
- GRB 200524A: Swift-XRT afterglow detection
- GRB 200524A: OAJ multicolor afterglow detection
- GRB 200524A: Fermi GBM detection
- GRB 200524A: 1.3m DFOT Optical Observation of ZTF20abbiixp
- GRB 200524A: 3.6m DOT observations of the afterglow candidate ZTF20abbiixp
- GRB 200524A: Fermi-LAT detection
- GRB 200522A: Swift-XRT refined Analysis
- GRB 200517A: Swift-XRT Confirmation of afterglow
- GRB 200514B: Fermi GBM observation
- GRB 200519A: 1.3m DFOT Optical Afterglow Detection
- GRB 200519A: Swift-XRT refined Analysis
- GRB 200519A: iTelescope optical afterglow detection
- GRB 200517A: Swift-XRT afterglow detection
- GRB 200512A: Swift-XRT refined Analysis
- Fermi-LAT Gamma-ray Observations of IceCube-200512A
- IceCube-200512A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- GRB 200509A: Swift-XRT refined Analysis
- GRB 200424A: Swift-XRT afterglow detection
- SGR 1935+2154 the Insight-HXMT observation plan
- IceCube-200425A: No significant detection in HAWC
- Fermi-LAT Gamma-ray Observations of IceCube-200425A
- IceCube-200425A: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
- GRB 200424A: Swift/UVOT Upper Limits
- GRB 200425A: Swift-XRT refined Analysis
- GRB 200424A: Swift-XRT observations
- GRB 200415A (possible magnetar Giant Flare in Sculptor Galaxy): INTEGRAL observations
- Fermi-LAT Gamma-ray Observations of IceCube-200421A
- IceCube-200421A: No significant detection in HAWC
- IceCube-200421A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- GRB 200410A: Optical upper limit
- GRB 200412B: Swift XRT confirmation of afterglow and UVOT upper limits
- GRB 200415A: Fermi-LAT localization update
- GRB 200416A: Fermi GBM observation
- GRB 200415A: Fermi GBM observation
- GRB 200415A: Fermi-LAT detection
- GRB 200412B: Xinglong TNT optical observations
- GRB 200412B: SAO RAS observations of OT
- IceCube-200410A: No significant detection in HAWC
- GRB 200405B: Further Swift-XRT observations
- GRB 200412B: Swift-XRT afterglow detection
- GRB 200412B: Fermi GBM detection
- GRB 200412B: Fermi-LAT detection
- GRB 200412A: Fermi GBM detection
- Fermi-LAT Gamma-ray Observations of IceCube-200410A
- GRB 200411A: Fermi GBM observation
- GRB 200411A: Swift-XRT refined Analysis
- IceCube-200410A: Possible associated excess in INTEGRAL SPI-ACS prompt observation
- SGR 1935+2154: Fermi GBM observation
- LIGO/Virgo S200225q: Swift XRT observations, 1 X-ray sources
- LIGO/Virgo S200224ca: Swift XRT observations, 8 X-ray sources
- GRB 200410A: Swift-XRT refined Analysis
- GRB 200409A: Swift-XRT refined Analysis
- GRB 200405B: Swift-XRT observations
- LIGO/Virgo S200316bj: Upper limits from Konus-Wind observations
- LIGO/Virgo S200311bg: Upper limits from Konus-Wind observations
- LIGO/Virgo S200302c: Upper limits from Konus-Wind observations
- LIGO/Virgo S200225q: Upper limits from Konus-Wind observations
- LIGO/Virgo S200224ca: Upper limits from Konus-Wind observations
- GRB 200325B: Optical upper limit
- GRB 200325B: further Swift-XRT observations
- GRB 200327A: Fermi GBM detection
- GRB 200325B: Fermi GBM observation
- GRB 200325B: Swift-XRT and UVOT observations
- GRB 200325A: Fermi GBM observation
- GRB 200324A: AROMA-N Optical Observation
- GRB 200324A: Swift-XRT refined Analysis
- GRB 200324A: NOT optical upper limit
- GRB 200323A: Fermi GBM detection
- Chandra observations of GW170817 at 2.5 years since merger (All epochs 4 of 4)
- GW170817: Continued X-ray emission detected with Chandra at 940 days post-merger
- LIGO/Virgo S200316bj: No counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S200213t: Continued Swift UVOT and XRT observations of ZTF20aamvmzj (AT2020cja)
- LIGO/Virgo S200316bj: No counterpart candidates in INTEGRAL SPI-ACS, and IBIS prompt observation
- LIGO/Virgo S200316bj: upper limits from AGILE/MCAL observations
- GRB 200313A: Fermi GBM detection
- LIGO/Virgo S200311bg: No significant counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S200311bg: No counterpart candidates in INTEGRAL SPI-ACS,prompt observation
- Chandra observations of GW170817 ~ 2.5 years since merger (epoch 1 of 4)
- GRB 200306C: Swift-XRT refined Analysis
- GRB 200306A: Swift-XRT refined Analysis
- GRB 200303A: Fermi GBM observation
- GRB 200303A: Swift-XRT refined Analysis
- LIGO/Virgo S200302c: No significant counterpart candidates in Fermi-LAT observations
- LIGO/Virgo S200302c: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
- LIGO/Virgo S200302c: upper limits from AGILE/MCAL observations
- GRB 200228B: Swift-XRT refined Analysis
- GRB 200228B: Fermi GBM observation
- GRB 200228A: Fermi GBM observation
- LIGO/Virgo S200213t: No significant EM counterparts identified from continued GECKO observation of host galaxy candidates
- Fermi-LAT Gamma-ray Observations of IceCube-200227A