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 070917: MITSuME Akeno Ic upper limit
- GRB 070917: R band observations
- GRB 070917, Swift-BAT refined analysis
- GRB 070917: Swift detection of a bright burst
- GRB 070911: Suzaku WAM observation of the prompt emission
- GRB 070913: Swift-XRT detection of the possible X-ray afterglow
- GRB 070809: The Swift evidence for the SHB nature of this burst
- GRB 070913: Afterglow candidate detected by TAROT La Silla observatory
- GRB 070913: Swift-BAT refined analysis
- GRB 070913: Corrected BAT position
- GRB 070913: SMARTS optical/IR observations
- GRB 070913: TAROT La Silla observatory optical observations
- GRB 070913: Swift detection of a burst
- Swift-BAT Notices back to autonomous real-time distribution
- GRB 070911: PAIRITEL IR Observations
- GRB 070911: Swift XRT refined analysis
- GRB 070911, Swift-BAT refined analysis
- GRB 070911: Swift detection of a burst
- IPN search for a GRB associated with TAROT transient on August 31
- Intense burst from SGR 1806-20 detected on September 7
- GRB 070809: Confirmation of optical transient
- Observations of possible TAROT GRB transient near IC 4779
- Candidate Orphan GRB Optical Transient in IC 4779
- GRB 070810b: Image Subtraction of Multiple Keck Observations
- Las Campanas observations of possible TAROT GRB transient near IC
- Orphan GRB candidate in IC 4779 at TAROT La Silla observatory
- Konus-Wind observation of GRB 070824
- GRB 070824 - Combined SuperAGILE/IPN Localization
- Konus-Wind observation of very bright GRB 070821
- GRB 070731: Swift/UVOT Upper Limit
- IPN Localization of GRB 070821 (long, very bright)
- GRB 070805: UVOT afterglow candidate retraction
- GRB070810b: optical candidate
- GRB 070810A: ROTSE-III Refined Analysis
- Swift observatory off line
- GRB 061110A: redshift confirmed
- GRB 070810B : Faulkes Telescope South Observations
- GRB 070810A: Continued Keck Imaging
- GRB 070810B: Keck spectroscopy of possible host galaxies
- GRB070810B: Swift/UVOT Upper Limits
- GRB 070810B: XRT refined analysis
- GRB 070810B, Swift-BAT refined analysis
- GRB 070810: MASTER optical observation
- GRB 070809: Swift/UVOT Corrected Photometry
- Swift Alert 070810.8: MASTER optical observation
- Swift Trigger 287421: False trigger due to star tracker loss
- GRB 070810A: Swift-BAT refined analysis
- GRB 070810B: Xinglong TNT optical Upper Limit
- GRB070810B: Optical observations with KANATA
- A giant outburst from Cygnus X-1 detected by Konus-Wind and Suzaku-WAM
- GRB 070809: Swift/UVOT Upper Limits
- GRB 070810B: Swift detection of a short burst
- VLA upper limit on the short hard burst GRB 070729
- GRB 070810: Keck redshift and photometry
- No radio detection in superAGILE burst 070724B
- GRB 070809: Keck Imaging
- GRB 070810: Swift-XRT Team Refined Analysis
- GRB 070809: Swift-XRT refined analysis
- GRB 070810: enhanced Swift-XRT position
- GRB 070810: Swift/UVOT Optical Counterpart
- GRB 070810: ROTSE-III Detection of Optical Counterpart
- GRB 070810: Swift detection of a burst
- GRB 070809, Swift-BAT refined analysis
- GRB 070809: Optical Pre-imaging from Palomar
- GRB 070808: Swift/UVOT upper limits
- GRB 070809: ROTSE-III Optical Limits
- GRB 070809: Swift detection of a short burst
- GRB 070808 : Faulkes Telescope South Observations
- GCN Swift XRT update position notices and enhanced position circulars
- GRB 070808: Swift XRT refined analysis
- GRB 070808, Swift-BAT refined analysis
- GRB 070808: OPTIMA-Burst optical upper limit
- GRB 070808: Xinglong TNT optical Upper Limit
- GRB070808: Optical observations with KANATA
- GRB070808 - SDSS Pre-Burst Observations
- GRB 070808: ROTSE-III Optical Limits
- GRB 070808: Swift detection of a burst
- GRB061121A: PROMPT Observations
- GRB070805 XRT and UVOT afterglow candidate
- Swift trigger on 4U 1700-377 while star tracker loss-of-lock
- GRB070612A: Radio upper limit from GMRT
- GRB 070721B: correct afterglow position
- Swift/UVOT observations of GRB070805
- GRB 070805, Swift-BAT refined analysis
- GRB 070805: Swift XRT initial analysis.
- GRB 070805: Swift/UVOT initial analysis
- GRB 070805: Swift detection of a burst
- UVOT observations of SAXJ1810.8-2609
- Swift detection of a outburst from SAX J1810.8-2609
- VLA non-detection of GRB 070721B
- GRB 070802: REM optical observations
- GRB 070724B: Swift-XRT afterglow confirmation
- GRB 070802: Swift-XRT refined analysis
- GRB070802: Swift/UVOT upper limits
- GRB 070802: Confirmation of the optical afterglow
- GRB 070802, Swift-BAT refined analysis
- GRB 070802: VLT redshift
- GRB 070802: refined Swift XRT position
- GRB 070802: V-band detection of the candidate afterglow
- GRB 070802: LCO I-band candidate