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"- GRB070208: optical observations
- GRB 070201: IPN constraints and nearby galaxies
- GRB 070201: Proximity of IPN annulus to M31
- GRB 070208: MARGE Optical Observations
- IPN localization of very bright long hard GRB 070207
- IPN localization of very intense short GRB 070201
- GRB 070209, Swift-BAT refined analysis of the short hard burst
- GRB 070209: Swift detection of a short hard burst
- GRB 070208: Swift XRT refined analysis
- GRB 070208: RAPTOR detection of early afterglow onset
- GRB070208: Absorption and emission redshift from Gemini
- GRB 070208: MDM Optical Decay
- GRB 070208, Swift-BAT refined analysis
- GRB070208 - SDSS Pre-Burst Observations
- GRB 070208: Early IR detection and afterglow astrometry
- GRB 070208: Afterglow confirmation from P60
- GRB070208: Faulkes Telescope North Afterglow Identification
- GRB 070208: ROTSE-III Optical Limits
- GRB 070208: MDM Observations
- GRB 070208: Swift detection of a burst
- GRB 070125 detection with CARMA
- Swift-BAT trigger 259527 is a Cosmic Ray Shower
- GRB 070125: Redshift z>~1.54 from Gemini Afterglow Spectrum
- GRB 070129: afterglow confirmation
- GRB070124: Swift-XRT Follow-up Observation
- GRB070126: Swift-XRT Observation
- GRB 070125: further AAVSO optical observations
- GRB 070129: Swift/UVOT Upper limits
- GRB 070129: dust-scattered X-ray halo detected by Swift/XRT
- GRB 070125: optical observation
- GRB 070125: WSRT Radio Detection
- GRB070129: MITSuME optical observation
- Radio detection of GRB 070125
- GRB061217: MAGIC telescope GeV observation
- GRB 070125: confirmation of pseudo-redshift
- GRB 070129, Swift-BAT refined analysis of a particularly long
- GRB 070129: Xinglong TNT optical Upper Limit
- GRB 070129: Swift-XRT Refined Analysis
- GRB 070129: VLT observations
- GRB 070125: An IR Point Source and an Apparent Host Galaxy
- GRB 070129: Swift detection of a burst
- GRB 070126: Swift/UVOT refined analysis
- GRB 070125: further AAVSO optical observations
- GRB 070125: MITSuME Okayama optical observation
- Konus-Wind observation of GRB 070125
- GRB 070125: AAVSO optical observations
- GRB 070125: optical observations
- GRB 070126: VLT observations
- GRB070126: Swift-XRT possible detection of an afterglow
- GRB 070125: PROMPT detections
- GRB 070124: Suzaku WAM observation of the prompt emissions
- GRB 070125: WSRT Radio Observations
- GRB 070125: UVOT Detection in Ultraviolet Filters
- GRB 070126, Swift-BAT refined analysis of a very faint burst
- GRB070125: Optical observation by Kanata
- GRB070124: Swift-XRT Observation
- Possible GRB 070126: Swift/UVOT Upper Limit
- GRB 070125: UVOT Observations of a Fading Optical Afterglow
- GRB 070125: Xinglong TNT optical observations
- GRB 070125: Continued P60 Observations
- GRB 070125: pseudo-z~1.5 from spectral parameters of the prompt emission
- GRB 070125: Keck/LRIS Spectroscopy -- Evidence for a very low redshift
- GRB 070125: Lick 3m Spectroscopy
- GRB070125: Swift-XRT Refined Analysis
- GRB 070125: SARA detection in R
- GRB 070125: P60 Optical Afterglow Candidate
- GRB 070126?: Swift detection of a possible burst
- GRB070125 redshift request
- RHESSI Spectrum of GRB070125
- IPN-BAT localization of GRB070125 (very long duration, intense)
- Konus-Wind observation of short hard GRB 070124
- IPN localization of GRB070124 (short duration, hard spectrum)
- GRB 070110: optical break
- Swift-BAT trigger 257213 is a Galactic Center transient
- GRB 070110: Continued Detection and Request for Ground Followup
- GRB 050904: Second Epoch of HST/NICMOS Observations
- GRB 070110: Ep,i - Eiso correlation
- GRB 070107: Suzaku WAM observation of the prompt emission
- GRB 070110: VLT R-band photometry
- GRB 070110 declared a "Burst of Interest" by Swift team
- Further Retractions of previous Swift-BAT triggers
- Swift-BAT Trigger 255685 is not a GRB
- Trigger 255685: Swift detection of a possible burst
- GRB 070110: VLT absorption redshift
- GRB 070110: UVOT Observations of a Candidate Afterglow
- GRB070110: Swift XRT Team refined analysis
- GRB 070110, Swift-BAT refined analysis
- GRB070107 Swift/UVOT Observations of a Fading Optical Afterglow
- GRB 070110: Swift detection of a burst with a possible optical afterglow
- IBAS Alert n. 4047: Not a GRB
- GRB070107: Swift/XRT refined analysis
- GRB 070107: Possible UVOT Afterglow
- GRB 070107, Swift-BAT refined analysis
- GRB 070107: Swift/XRT position
- GRB 070107: Swift detection of a burst
- VLA observation of GRB 061222B
- VLA detection of GRB 061222A
- GRB070103: APO SPIcam i' and z' limits
- GRB 061201: Nearby Galaxy Cluster Abell 995 is at z=0.0865
- GRB070103: KPNO 4m+FLAMINGOS J limit