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"- GRB050326: optical limit
- GRB 050326: Early observations with Swift-UVOT
- GRB 050326 XMM-Newton observation
- GRB 050326 : Planned XMM-Newton observation
- GRB 050326: Swift XRT Position
- GRB050326: optical limit 33min before GRB
- GRB 050326 BAT refined analysis
- GRB050326: delayed XRT observation
- Swift-BAT detection of a bright GRB 050326
- GRB050319, optical observations
- GRB050319, color indices
- GRB050319: optical observation, March 20-22
- GRB050319: RTT150 Optical Observations
- Swift-BAT detection of a bright outburst from SGR1806-20
- Swift-BAT trigger 112060 is not a real GRB
- GRB 050319: Absorption redshift from the Nordic Optical Telescope
- GRB 050319: ROTSE-III Refined Analysis
- GRB 050318: Swift-BAT refined analysis
- Refined Swift XRT positions for GRB050315, GRB050318 and GRB050319
- GRB050319: VLA Observations
- GRB050319: radio observation
- GRB 050319 R band observations
- GRB 050319: Swift-UVOT detection of the afterglow
- GRB 050315: Variability Analysis of Swift BAT Time History
- GRB050319: Radio Observations
- GRB 050319: NIR afterglow candidate
- GRB 050319:Near IR afterglow
- GRB050319: BR optical photometry
- GRB 050318: SWIFT-UVOT refined analysis
- GRB 050318: Absorption redshift from Magellan
- GRB 050319: Optical observation
- GRB 050319 : Confirmation of optical afterglow decay
- GRB 050319: Swift-BAT refined analysis
- GRB050319,optical observation
- Swift Detection of GRB 050319
- GRB 050319: Detection of Possible Optical Counterpart
- GRB 050318: Swift/UVOT detection of afterglow emission
- GRB 050318: Magellan optical afterglow identification
- GRB050318: Swift XRT position
- RXTE Observations of GRB050318
- Swift-BAT detection of GRB 050318
- GRB 050315, SMARTS optical afterglow decay
- GRB050223: analysis of the XMM-Newton observation
- GRB050316: MASTER before, simultanious and follow up optical
- GRB 050306: ROTSE-III early limits
- GRB050316: MASTER optical observations
- GRB 050315: Swift-BAT further refined analysis
- GRB 050315, SMARTS optical/IR afterglow observations
- GRB 050315 I-band observations
- GRB050315: Radio afterglow
- GRB 050315: Absorption redshift
- GRB 050315: Optical afterglow identification
- GRB050315: Swift-BAT Refined analysis
- Non-detection of GRB050315 in ATCA Radio Observations
- GRB 050315: Swift XRT Position
- GRB 050219b: Gemini/GNIRS near-infrared spectroscopy
- GRB 050315: Early Observations with Swift/UVOT
- Swift-BAT detection of GRB 050315
- GRB050223: No XMM-Newton OM detection of afterglow emission
- GRB 050306: Radio Observations
- GRB050306: 250 GHz upper limit with MAMBO at the IRAM 30m
- GRB050309: CONCAM pre-trigger and trigger coincident optical
- GRB 050306: optical afterglow
- GRB 050126: Redshift determination
- Swift-BAT trigger 107873: No Swift XRT counterpart
- GRB 050306: Confirmation of X-ray afterglow
- GRB 050309, Early optical limits from RAPTOR
- GRB 050306: further TAROT optical data
- GRB050309: Early optical limit from P60
- Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
- GRB 050309 : Lulin R-band observation
- Swift 107873: P60 Optical Observations
- GRB 050306: CORRECTION to date of observation
- GRB 050306: R-band observations
- GRB 050306: No Swift UVOT Optical Counterpart Detected
- GRB 050306: REM optical-infrared observations
- GRB 050306: Possible X-ray Afterglow Position from the Swift
- Swift trigger 107518: optical observation
- GRB 050306: TAROT optical observations
- GRB 050306,optical observation
- GRB 050306: Swift-BAT detection of a long burst
- Ongoing activity of SGR 1806-20 after the giant flare
- GRB050215B: Late-Time Swift UVOT Observations
- GRB 050126: Confirmation of the NIR afterglow candidate
- PROMPT VRcIc Observations of GRB 050223
- XRF/GRB 050215B: Radio Observations
- XMM-Newton Images of GRB 050223
- GRB 050219b: candidate NIR afterglow
- IBAS GRB Alert #2321
- Confirmed XRF nature for GRB050215b
- GRB 050223: optical observations
- GRB050223 XMM-Newton observation
- INTEGRAL detection of GRB 050223
- GRB 050223 : Planned XMM-Newton observation
- GRB050223: No Swift UVOT Detection of Afterglow Emission
- GRB050223: ROTSE-III Optical Observations
- GRB 050223 Swift/BAT detection of a burst
- GRB 050223: Swift XRT Position
- HETE-2 Observations of GRB 050215b (=U11570): A Likely X-Ray Flash
- GRB050219b: CORRECTION to time of UVOT observations