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').
18309 results found.
- GRB 240516A ATCA radio observations
- IPN triangulation of GRB 240514B (short)
- GRB 240513A: Swift ToO observations
- GRB 240516A: AstroSat CZTI detection
- GRB 240516A: Swift-XRT refined Analysis
- GRB 240514E: A possible candidate BD-21 1074
- GRB 240516A: Fermi GBM Observation
- GRB 240516A: GOTO optical upper limit
- GRB 240516A: Swift detection of a burst
- Swift GRB240516.15: Global MASTER-Net observations report
- GRB 240513A: Swift-XRT observations
- LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
- LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
- GRB 240513A: Tiled Swift observations
- GRB 240513A: Fermi-LAT detection
- GRB 240511A: Fermi GBM Observation
- GRB 240511A: Swift-BAT refined analysis
- GRB 240511A: J-band observations with WINTER
- GRB 240511A: Enhanced Swift-XRT position
- GRB 240511A : MITSuME Akeno optical upper limits
- GRB 240511A: Swift-XRT refined Analysis
- Swift GRB 240511A: Global MASTER-Net observations report
- GRB 240511A: Prompt enhanced Swift-XRT position
- GRB 240511A: Swift detection of a burst
- GRB 240504A: Fermi GBM Observation
- IPN triangulation of GRB 240504A
- GRB 240504A: Swift/BAT-GUANO detection of a burst outside the coded FOV
- GRB 240415A 1.3m DFOT Optical upper limit
- LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
- LVK S240422ed: Further Swift-XRT followup of three sources
- LIGO/Virgo/KAGRA S240422ed: Magellan Follow-up Observations of Swift/XRT candidates
- LIGO/Virgo/KAGRA S240422ed: 2.5m PRL Telescope follow-up of the Swift/XRT source S240422ed_X190
- LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-FXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
- LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limits for Swift/XRT candidates
- GRB 240419B: Swift-BAT refined analysis
- GRB 240421B: Swift-BAT refined analysis
- LIGO/Virgo/KAGRA S240422ed: Himalayan Chandra Telescope follow-up of the Swift/XRT source S240422ed_X101
- IceCube-240424A - IceCube observation of a high-energy neutrino candidate track-like event
- LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Potential Electromagnetic Counterparts Reported by Swift and DECam
- LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
- LIGO/Virgo/KAGRA S240422ed: NOT J-band upper limit on the Swift/XRT source S240422ed_X61
- LIGO/Virgo/KAGRA S240422ed: X-ray Upper Limits from EP-WXT for the Three Potential Electromagnetic Counterparts Reported So Far
- GRB 240421B: GRBAlpha detection
- LIGO/Virgo/KAGRA S240422ed: WINTER J-band upper limits on the Swift/XRT source S240422ed_X61
- LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
- GRB 240419A: Swift-BAT refined analysis
- GRB 240418A: Swift-BAT refined analysis
- LXT240402A/GRB240402B: Chandra X-ray detection
- LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
- GRB 240419B : MITSuME Akeno optical upper limits
- GRB 240415B: Swift-XRT observations
- GRB 240415A: Swift-XRT refined Analysis
- GRB 240421B: AstroSat CZTI detection
- GRB240421B: Zadko Observations
- Swift GRB 240421B: Global MASTER-Net observations report
- GRB 240421B: Fermi GBM Observation
- GRB 240421B: Swift-XRT refined Analysis
- GRB240421B: BOOTES-5/JGT optical upper limit
- GRB 240421B: Swift/UVOT Upper Limits
- GRB 240421B: Enhanced Swift-XRT position
- GRB 240421B: Swift detection of a burst
- GRB240419A: Skynet Optical Afterglow Analysis
- GRB 240419B: Swift/UVOT Upper Limits
- GRB 240419A: Swift/UVOT Upper Limits
- GRB 240419B: Swift-XRT refined Analysis
- Swift GRB 240419B: Global MASTER-Net observations report
- GRB 240419B: Enhanced Swift-XRT position
- Swift GRB 240419A: Global MASTER-Net observations report
- GRB 240418A: Swift/UVOT Upper Limits
- GRB 240419A: Swift-XRT refined Analysis
- GRB 240418A: Swift-XRT refined Analysis
- GRB 240419B: Swift detection of a burst
- GRB 240411B: Swift/UVOT Detection
- GRB240418A: YAHPT Upper Limits
- GRB 240419A: Enhanced Swift-XRT position
- GRB 240419A: Prompt enhanced Swift-XRT position
- GRB 240419A: Swift detection of a burst
- GRB 240418A: TSHAO Zeiss-1000 optical upper limit
- GRB 240418A: Enhanced Swift-XRT position
- Swift GRB240418.85: Global MASTER-Net observations report
- GRB 240418A: Swift detection of a burst
- Improved IPN triangulation of GRB 240411A
- GRB 240415A: Glowbug gamma-ray detection
- GRB 240414A: Glowbug gamma-ray detection
- GRB 240415B: GECAM-B detection
- GRB 240415A: Swift-BAT refined analysis
- GRB 240411A: Glowbug gamma-ray detection
- GRB 240414A: Swift-BAT refined analysis
- GRB 240414A: AbAO optical upprer limit
- GRB 240415A: Swift/UVOT Detection
- GRB 240415A: Fermi GBM Observation
- GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
- GRB 240415A: Enhanced Swift-XRT position
- GRB 240415B: Swift ToO observations
- GRB 240415B: Swift/BAT-GUANO Correction
- GRB 240415B: Swift/BAT-GUANO arcminute localization of a short burst
- GRB 240414A: Fermi GBM Observation
- GRB 240414A: Swift/UVOT Detection
- LXT 240402A/GRB 240402B: Swift follow-up observations