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"- GRB 110112A: optical upper limit
- GRB 110120A: MASTER optical observations
- GRB110119: Swift/UVOT Detection
- GRB 110119A: Swift-XRT refined Analysis
- GRB110119A: MITSuME Okayama optical upper limits
- GRB 110119A: Swift-BAT refined analysis
- GRB 110119A: PAIRITEL NIR Afterglow Detection
- GRB 110119A: Enhanced Swift-XRT position
- GRB 110119A: Swift detection of a burst with an optical detection
- GRB110106A, mm-radio observations
- GRB 101219B: tentative redshift and spectroscopic supernova detection
- GRB 101219B: GROND detection of a SN signature
- Swift-BAT trigger 442771 is a noise fluctuation
- GRB 101219B: correction
- GRB 101219B: Likely the GRB host emission dominates now in the uvw2 filter
- New feature in Fermi GBM GRB Ground Position Notices
- Swift-BAT Trigger 442539 is not a GRB
- Swift Trigger 442539 is probably not a GRB
- Short GRB 110112B : early optical limit by "Pi of the Sky"
- GRB101225A - timing analysis
- GRB 110112B: Fermi GBM observation
- The Christmas burst GRB 101225A - optical spectroscopy with GTC
- GRB 110112B: Swift XRT and UVOT observations of the INTEGRAL burst
- GRB 110112A: MITSuME Akeno and Okayama optical upper limits
- GRB 110107A: Swift-XRT afterglow confirmation
- GRB 101225A: HST observations - no host detected
- GRB 101225A: Redshift retraction and results of additional photometric follow-up at the NOT
- GRB 110112B: A short GRB detected by INTEGRAL
- GRB 110112A: Swift-XRT refined Analysis
- GRB 110112A: Swift/UVOT upper limits
- GRB 110112A: WHT candidate afterglow/host galaxy
- GRB 110112A: MASTER optical observations
- GRB 110112A: Swift-BAT refined analysis
- GRB 110112A: Enhanced Swift-XRT position
- GRB 110106B: MASTER optical observations
- GRB110112A: TNT optical afterglow candidate
- GRB 110112A: Swift detection of a possible short burst
- GRB 110106B: early optical and near-IR observations
- GRB 110107A: Swift/UVOT upper limits
- GRB 101225a
- GRB 101219b. Possible radio afterglow detection.
- GRB 110106B: MASTER early optical observations
- GRB 110107A: Swift-XRT Afterglow Candidate
- GRB 110107A: Swift-BAT refined analysis
- GRB 110107A detected in ground analysis of BAT slew data
- GRB 101213A: Gemini-N galaxy redshift
- GRB 110106B: Fermi GBM detection
- Short GRB 110106A: MASTER OT observations
- GRB 110106B: Swift-XRT refined Analysis
- GRB 110106B: Gemini-North / WHT detection of a fading afterglow
- GRB 110106A: TNG NIR observations
- GRB 110106B Gemini-N galaxy redshift
- GRB 110106B: Liverpool Telescope observations
- GRB 110106A: ISAS-Kanazawa optical upper limit
- GRB 110106A: MITSuME Okayama optical upper limits
- GRB 110106B: WHT candidate afterglow
- GRB 110106B: Swift-BAT refined analysis
- GRB 110106B: Enhanced Swift-XRT position
- GRB 110106A: Swift/UVOT Upper Limits
- GRB 110106A: TNG redshift of the closeby galaxy
- GRB 110106A: Swift-XRT refined Analysis
- GRB110106B: Xinglong TNT upper limit
- GRB 110106A: Swift-BAT refined analysis
- GRB 110106A: Enhanced Swift-XRT position
- GRB 110106B: Swift detection of a burst
- GRB 110106A: TNG optical observations and candidate counterparts
- GRB 110106A: MASTER optical observations
- GRB 101225A: Keck redshift
- GRB110106A: Xinglong TNT upper limit
- GRB 110106A: Swift detection of a burst
- GRB 101225A: Host galaxy
- GRB 101219A: Gemini-North host redshift
- GRB 110102A: Swift-XRT refined Analysis
- GRB 101219B: After 2 weeks still detected by Swift/UVOT
- Konus-Wind observation of GRB 110102A
- GRB110102A: Swift/UVOT observations
- GRB110102A: MITSuME Okayama Optical Observation
- GRB 110102A: Fermi GBM observation
- GRB 110102A: Swift-BAT refined analysis
- GRB 110102A: Enhanced Swift-XRT position
- GRB 110102A: Swift detection of a burst with an optical detection
- GRB 101225A: optical break from NOT observation
- GRB 101225A: MMT spectroscopy
- GRB 101225A: P60 Observations
- GRB 101225A: MAXI/GSC observations
- GRB 101225A Late-time emission observed by Swift-BAT
- GRB 101225: Optical follow-up of the Christmas burst
- GRB 101225A: WHT observations
- Tentative redshift of GRB101225A (Christmas's burst) from Swift-XRT data
- GRB 101225A, Swift-BAT refined analysis
- GRB 101225A: Swift/UVOT Detection
- GRB 101225A: Swift-XRT refined Analysis
- GRB 101225A: Enhanced Swift-XRT position
- Trigger 441015 / GRB 101225A: Further NOT optical observation
- Trigger 441015 / GRB 101225A: NOT optical afterglow candidate
- GRB 101225A (Swift trigger 441015): optical upper limit
- Trigger 441015: Swift detection of a possible burst or transient
- GRB 101224A: NOT optical observation
- GRB 101224A: Pre-event imaging from DeepSky; Detection of a source in the XRT error circle
- GRB 101224A: Swift/UVOT Upper Limits