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"- GRB120521B: Faulkes Telescope South observations
- GRB 120521B: TAROT La Silla observatory optical observations
- GRB 120521B: Swift detection of a burst
- GRB 120521A: Enhanced Swift-XRT position
- GRB 120521A: TAROT La Silla observatory optical observations
- GRB 120521A: Swift detection of a short burst
- GRB 120514A : Suzaku WAM observation of the prompt emission
- GRB 120512A: A long GRB detected by INTEGRAL
- Swift Trigger 522245 is a noise fluctuation near IGR J17091-3624
- GRB 120514A: GROND upper limits
- GRB 120514A: Swift/UVOT Upper Limits
- GRB 120514A: UKIRT IR observations
- Konus-Wind observation of GRB 120510A
- GRB 120514A: Swift-XRT refined Analysis
- GRB 120514A: APEX observations of the submm counterpart
- GRB 120514A: Enhanced Swift-XRT position
- GRB 120514A: Swift-BAT refined analysis
- GRB 120514A: TAROT Calern observatory optical observations
- GRB 120514A: Swift detection of a burst
- GRB 120422A: Konkoly optical observations
- Fermi GBM Trigger 358364818 is not a GRB
- Fermi Trigger 358364818: BOOTES-4 observations
- GRB 120510B/Fermi Trigger 358364818: MASTER possible OT candidate
- GRB 120510A: Swift XRT and UVOT observations
- GRB 120510A: MASTER follow up observations
- GRB 120510A: MAXI/GSC detection of a burst
- GRB 120422A: SN identification from GTC
- Fermi/GBM detection of a burst from the magnetar 1E 2259+5
- GRB 120422A: P200 NIR detection
- GRB 120422A: CARMA 3mm observations
- GRB 120422A: VLT/X-shooter spectroscopic evidence for a SN
- GRB 120422A: Gemini-N detection of a supernova
- GRB 120422A: i-band re-brightening and possible SN detection
- GRB 120427A: MASTER follow up observations
- GRB 120422A: optical observations
- Konus-Wind observation of GRB 120427A
- IPN Triangulation of GRB 120427A
- Swift detection of 4U 1630-47
- GRB 120422A, the review of the sky area in plate archives
- Konus-Wind observation of GRB 120426A
- GRB 120422A: Additional Gemini observations and Keck/LRIS spectroscopy
- IPN Triangulation of bright GRB 120426A
- Swift Trigger 520928 is a noise event
- GRB 120422A: MITSuME Ishigakijima upper limit
- Swift Trigger 520928 is probably not a burst
- GRB 120424A: MAXI/GSC detection of a burst
- GRB 120422A: 272 GHz observations from SMA
- GRB 120422A: JCMT SCUBA-2 sub-mm observation
- GRB 120422A: RAPTOR Limits During Gamma-ray Emitting Interval
- GRB 120422A: VLT/X-shooter spectroscopy of the GRB counterpart
- GRB 120422A GROND observations
- GRB 120422A: Super-LOTIS early observations
- GRB 120422A: EVLA Detection
- GRB 120422A: Xinglong TNT optical upper limit
- GRB 120422A: NOT optical observations
- GRB 120422A: Gemini redshift of candidate host
- GRB 120422A: Zadko observatory - Gingin optical observations
- GRB 120422A: Swift-XRT refined Analysis
- GRB 120422A: A Swift/UVOT Detection
- GRB 120422A: Enhanced Swift-XRT position
- GRB 120422A: Swift-BAT refined analysis
- GRB 120422A: Gemini observations
- GRB 120422A: Faulkes Telescope North observations
- GRB 120422A: Swift detection of a burst
- GRB 120419A: Swift-XRT and UVOT observations
- GRB 120419A: A long GRB detected by INTEGRAL
- Swift Trigger 519874 is a noise event
- SGR1806-20, Swift-BAT refined analysis (Trigger 519868)
- Swift Trigger 519874 is probably a noise event
- Trigger 519868: Swift detection of SGR1806-20
- GRB 120404A: optical observations in Mondy observatory
- GRB 120404A: optical observations
- GRB 120404A, Optical Observations
- GRB 120404A: JCMT SCUBA-2 sub-mm observation
- GRB 120404A: SMARTS optical/IR observations
- GRB 120404A: EVLA Detection
- GRB 120404A: MASTER OT observations
- GRB120404A: GROND observations show steeply decaying afterglow
- GRB120404A: MOA optical observations of the initial rise afterglow
- GRB 120404A: VLT/X-shooter redshift confirmation
- GRB 120404A: Swift/UVOT Detection
- GRB 120404A: MITSuME Ishigakijima Optical Observation
- GRB 120404A: MITSuME Okayama Optical Observation
- GRB 120403B: Swift-XRT refined Analysis
- GRB 120404A: Swift-XRT refined Analysis
- GRB 120404A : TNT optical observation
- GRB 120404A: Swift-BAT refined analysis
- GRB 120401A: GROND Detection of an optical/NIR afterglow candidate
- GRB 120404A: Enhanced Swift-XRT position
- GRB 120404A: Gemini-N Redshift correction
- GRB 120402B: MASTER early OT limit
- GRB 120403B: TAROT La Silla observatory optical observations
- GRB 120403B: Fermi GBM Observation
- GRB 120404A: Gemini-N Redshift
- GRB 120403B: AAT nIR observations
- GRB 120404A: MITSuME Akeno Optical upper limits
- GRB 120404A: MASTER early OT limit
- GRB 120404A: Faulkes Telescope North afterglow confirmation
- GRB 120404A: Swift detection of a burst with an optical counterpart
- GRB 120403B: Swift-BAT refined analysis