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.
Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
- GRB 221221A: AGILE detection
- Fermi GRB 221221A: Global MASTER-Net observations report
- GRB 221221A: Fermi GBM Final Real-time Localization
- GRB 221218A: 3.6m DOT optical upper limit
- IceCube-221216A: No Candidate Counterparts from the Zwicky Transient Facility
- GRB 221216A: Detection by VZLUSAT-2
- GRB 221218A: MITSuME Akeno optical upper limits
- GRB 221218A: BOOTES-4/MET and OSN optical upper limits
- GRB 221218A: KAIT Optical Upper Limit
- IceCube-221210A: BOOTES-4/MET and Lijiang 2.4-meter Telescopes Optical Observations
- GRB 221215A: Fermi GBM Detection
- GRB 221218A: a long GRB detected by INTEGRAL
- Integral GRB221218.34: Global MASTER-Net observations report
- Fermi-LAT gamma-ray observations of IceCube-221216A
- IceCube-221216A: Upper limits from a search for additional neutrino events in IceCube
- GRB 221216A: Swift/UVOT Upper Limits
- GRB 221216A: Fermi GBM observation
- GRB 221216A: Swift-XRT refined Analysis
- Fermi-LAT gamma-ray observations of IceCube-221210A
- IceCube Alert 221216.25: Global MASTER-Net observations report
- GRB 221216A: AKO Upper Limit
- GRB 221215A: Swift-XRT observations
- GRB 221216A: Enhanced Swift-XRT position
- Swift GRB 221216A: Global MASTER-Net observations report
- GRB 221216A: Zadko observatory - Gingin optical observations
- GRB 221216A: Nanshan/NEXT optical upper limits
- GRB 221216A: Swift detection of a burst
- GRB 221216A: Fermi GBM Final Real-time Localization
- IceCube-221216A - IceCube observation of a high-energy neutrino candidate track-like event
- Fermi trigger No 692760884: Global MASTER-Net observations report
- GRB 221215A: Swift ToO observations
- GRB 221215A: Swift/BAT-GUANO arcminute localization
- Konus-Wind detection of GRB 221209A
- Fermi GRB 221215B: Global MASTER-Net observations report
- IPN triangulation of GRB 221209A (long)
- GRB 221215B: Fermi GBM Final Real-time Localization
- Fermi Gamma-ray Burst Monitor trigger 692760884/221215066 is not a GRB
- Swift GRB221215.15: Global MASTER-Net observations report
- Fermi trigger No 692713692: Global MASTER-Net observations report
- GRB 221215A: Fermi GBM Final Real-time Localization
- Swift Trigger 1144538 is not a GRB
- Fermi Gamma-ray Burst Monitor triggers 692721536/221214610 and 692713692/221214520 are not GRBs
- Konus-Wind detection of a burst from SGR 1935+2154 on 2022 December 13
- Fermi trigger No 692607435: Global MASTER-Net observations report
- GRB 221209A: CALET Gamma-Ray Burst Monitor detection
- IceCube-221210A: Upper limits from a search for additional neutrino events in IceCube
- GRB 221212A: Fermi GBM Final Real-time Localization
- Fermi GRB 221211A: Global MASTER-Net observations report
- GRB 221208A: AstroSat CZTI detection
- GRB 221211A: Fermi GBM Final Real-time Localization
- IceCube-221210A - IceCube observation of a high-energy neutrino candidate track-like event
- IceCube Alert 221210.36: Global MASTER-Net observations report
- GRB 221009A: MuSCAT3 observations
- GRB 221209A: AstroSat CZTI detection
- GRB 221210A: Fermi GBM Final Real-time Localization
- GRB 221209B: Fermi GBM Final Real-time Localization
- GRB 221209A: Fermi GBM observation
- GRB 221203C: AstroSat CZTI detection
- GRB 221209A: BALROG localization (Fermi Trigger 692257829 / GRB 221209243)
- GRB 221209A: Fermi GBM Final Real-time Localization
- GRB 221206B: Fermi GBM observation
- GRB 221206B: Swift-XRT observations
- GRB 221206B: Detection by GRBAlpha
- GRB 221206B: Swift/BAT-GUANO candidate arcminute localization
- GRB 221206B: Swift ToO observations
- Swift/BAT trigger #1143281 is not a GRB
- GRB 221206C: Fermi GBM Final Real-time Localization
- GRB 221206B: Fermi GBM Final Real-time Localization
- GRB 221206A: Fermi GBM Final Real-time Localization
- GRB 221205A: Fermi GBM Final Real-time Localization
- Swift GRB221204.45 AKO Upper Limit
- GRB 221202B: Detection by VZLUSAT-2
- Swift GRB221204.45: Global MASTER-Net observations report
- GRB 221203B: Fermi GBM Final Real-time Localization
- GRB 221202A: Swift/UVOT Detection
- GRB 221202A: Swift-BAT refined analysis
- GRB 221202A: VLT/FORS2 Afterglow Discovery
- GRB 221201A: Swift-BAT refined analysis
- GRB 221203A: Fermi GBM Final Real-time Localization
- GRB 221201A: Fermi GBM observation
- GRB 221202A: Swift-XRT refined Analysis
- GRB 221202A: LCOGT Optical Upper Limits
- GRB 221202A: Enhanced Swift-XRT position
- GRB 221202A: MeerLICHT upper limits
- GRB 221202B: Fermi GBM Final Real-time Localization
- GRB 221202A: Swift detection of a burst
- Swift GRB221202.84: Global MASTER-Net observations report
- GCN: GRB 221201A: Swift/UVOT Upper Limits
- GRB 221201A: Swift-XRT refined Analysis
- GRB 221201A: Enhanced Swift-XRT position
- Swift GRB 221201A: Global MASTER-Net observations report
- Konus-Wind detection of GRB 221124A
- GRB 221201A: Swift detection of a burst
- GRB 221201A: Fermi GBM Final Real-time Localization
- Fermi Gamma-ray Burst Monitor trigger 691534074/221130867 is not a GRB
- Optical polarization observation of GRB 221009A
- GRB 221126A: Fermi GBM observation
- IceCube-221124A: Upper limits from a search for additional neutrino events in IceCube
- GRB 221126A: AGILE detection
- GRB 221127A: Detection by GRBAlpha