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').
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"25905 results found.
- GRB 230307A: Tiled Swift observations
- IPN triangulation of GRB 230307A (long/very bright)
- GRB 230228A: 6 GHz VLA radio upper limit
- GRB 230228A: Swift-BAT refined analysis
- GRB 230228A: Swift/UVOT Upper Limits
- GRB 230228A: Fermi GBM Observation
- GRB 230228A: OSN optical upper limit
- GRB 230228A: Swift-XRT refined Analysis
- GRB 230228A: Mondy optical upper limit
- GRB 230228A: Enhanced Swift-XRT position
- GRB 230228A: Nanshan/NEXT optical upper limit
- GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
- GRB 230228A: Prompt enhanced Swift-XRT position
- GRB 230228A: Swift detection of a possibly short burst
- GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
- GRB 230216A Mondy Observations
- GRB 230205A: VLA radio afterglow confirmation
- GRB 230217A: Swift/UVOT Upper Limits
- GRB 230216A: Swift/UVOT Upper Limits
- GRB 230217A: Continued Gemini Observations
- GRB 230217A: Swift-XRT afterglow detection
- GRB 230217A: Swift-BAT refined analysis
- GRB 230217A: AstroSat CZTI detection
- GRB 230217A: Gemini South optical upper limits
- GRB 230217A: 6 GHz VLA observations
- GRB 230217A: Fermi GBM observation
- Konus-Wind detection of GRB 230217A
- GRB 230217A: Swift-XRT observations
- GRB 230217A: AGILE/MCAL detection
- GRB 230207B: CALET Gamma-Ray Burst Monitor detection
- GRB 230216A: SVOM/C-GFT optical upper limit
- GRB 230217A: Swift detection of a short burst
- GRB 230216A: Swift-BAT refined analysis
- GRB 230216A: Swift-XRT refined Analysis
- GRB 230205A: Lowell Discovery Telescope Observations
- Swift GRB 230216A: Global MASTER-Net observations report
- GRB 230216A: Enhanced Swift-XRT position
- GRB 230216A: AKO Upper Limit
- GRB 230216A: Zadko observatory - Gingin optical observations
- GRB 230216A: Swift detection of a burst
- GRB 230209B: AGILE detection
- GRB 230209B: Fermi GBM Observation
- IPN triangulation of GRB 230209B
- GRB 230204B: CALET Gamma-Ray Burst Monitor detection
- GRB 230209B: Swift/BAT-GUANO detection outside the coded FOV
- Swift Trigger 1153670 is probably not a GRB
- GRB 230205A: 6 GHz VLA observations
- GRB 230205A: SUBARU HSC pre-imaging for host galaxy search
- GRB 221009A: Continued Swift Observations
- GRB 230207B: Detection by GRBAlpha
- GRB 230205A: possible host galaxy detection with the Schmidt - Asiago telescope
- GRB 230207B: Swift/BAT-GUANO detection outside the coded FOV
- ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
- GRB 230204B: Swift/UVOT Upper Limits
- GRB 230205A: Swift/UVOT Upper Limits
- GRB 230204B: Fermi GBM detection
- GRB 230205A: LCOGT Optical Upper Limits
- GRB 230204B: Swift-XRT afterglow detection
- GRB 230205A: SVOM/C-GFT optical upper limit
- GRB 230204B: VLT/X-shooter redshift
- GRB 230205A: Swift-BAT refined analysis (T90 = 2.3 s)
- GRB 230204A: Swift-BAT refined analysis
- GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group
- GRB 230205A: Swift-XRT refined Analysis
- GRB 230204B: Swift ToO observations
- GRB 230205A: Enhanced Swift-XRT position
- GRB 230205A: BOOTES-5/JGT early optical upper limit
- GRB 230204B: Detection by GRBAlpha
- GRB 230204B: AGILE detection
- GRB 230205A: Swift detection of a burst
- GRB 230204B: GIT discovery of the likely optical afterglow
- GRB 230204B: AstroSat CZTI detection
- GRB 230204B: Swift/BAT-GUANO detection outside the coded FOV
- GRB 230204A: Swift/UVOT Upper Limits
- GRB 230204A: Swift-XRT refined Analysis
- GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
- GRB 230204A: Enhanced Swift-XRT position
- GRB 230204A: Swift detection of a possible burst (or possible transient Swift J1552.8-5055)
- GRB 221216A: Swift-BAT refined analysis
- ZTF23aabmzlp/AT2023azs: VLA radio detection
- ZTF23aaarlti/AT2023avj: AMI-LA radio detection
- ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
- GRB 221009A: radio afterglow detection with the EVN
- ZTF23aaarlti/AT2023avj: Assy continued optical observations
- AT2023avj: X-ray Detection with Swift/XRT
- ZTF23aabmzlp/AT2023azs: 1.3m DFOT optical observations
- ZTF23aaarlti/AT2023avj: VLA radio detection
- ZTF23aabmzlp/AT2023azs: GIT confirmation of the likely afterglow
- ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
- AT2023avj ZTF Candidate: Assy optical observations
- ZTF and LT Observations of AT2023avj, a Candidate Optical Afterglow
- Swift-XRT observations of NuEm-230125A
- Trigger 1150965: Swift detection of LS V +44 17
- GRB 230124A: Fermi GBM Observation
- GRB 230124A: Swift/BAT-GUANO detection outside the coded FOV
- GRB 230123A: LCOGT Optical Upper Limits
- GRB 230123A: Swift-BAT refined analysis
- GRB 230122A: Swift/BAT-GUANO detection
- GRB 230123A: Swift/UVOT Upper Limits
- GRB 230123A: Swift-XRT refined Analysis