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"6667 results found.
- GRB 050509b Milagro GeV/TeV Observations
- GRB 050509b: No Optical Variability in XRT Error Circle
- GRB 050509b: Possible Optical Counterpart
- GRB 050502a: Swift XRT Upper Limit
- GRB050505: Optical Afterglow Candidate
- GRB 050504, R band Observations
- GRB (?) 050504: IR Observations, Intriguing Source
- GRB050502A: Optical Observations
- GRB 050502: Confirmed variability of the afterglow candidate +
- GRB 050421: Further Analysis of IR imaging
- GRB 050421: IR Observations
- GRB050326: analysis of the XMM-Newton observation
- GRB050416B: IR observations
- GRB050416: P200 NIR Observations
- GRB 050412 : XingLong optical observation
- GRB050410 : Null detection report
- GRB 050408: Swift XRT measurement of possible jet break
- GRB 050408: SOAR UBVRc Observations
- GRB 050408: Swift XRT analysis
- GRB050408: REM NIR and Optical observation
- GRB 050406: early Swift XRT analysis results
- GRB 050402: Early observations with Swift-UVOT
- GRB 050326 XMM-Newton observation
- GRB050223: analysis of the XMM-Newton observation
- Swift-BAT trigger 107873: No Swift XRT counterpart
- Swift-BAT trigger 107873 (GRB050309): possible X-ray counterparts
- GRB 050309 : Lulin R-band observation
- GRB 050306: REM optical-infrared observations
- GRB 050126: Confirmation of the NIR afterglow candidate
- GRB 050219b: candidate NIR afterglow
- GRB 050219b: Optical and near-IR observations from LCO
- GRB 050215b : Lulin follow-up observation
- GRB 050126: Detection of NIR afterglow with Keck/NIRC
- GRB 050124: NIR afterglow confirmed with Keck/NIRC
- GRB 050124: NIR Candidates from Keck/NIRC
- GRB050117: Palomar WIRC Ks-band observations
- GRB050117: optical observation
- GRB 050117, I-band observations
- GRB 041217: Optical observations
- Giant flare from SGR 1806-20 detected by INTEGRAL
- NIR Observations of GRB 041219
- GRB041226: ROTSE-III Optical Observations
- Swift-BAT Time History of GRB041219
- GRB 041219 : optical follow-up observations
- Swift-BAT detection of the bright long burst GRB041219
- GRB 041211: Infrared Observations
- GRB 041211: Optical follow-up in East Asian region
- GRB041015: Near-Infrared observations
- GRB 040924: Afterglow Color
- GRB 041006: Optical Observations
- GRB041006: RTT150 Optical Observations
- GRB041015 : Multi epoch optical observations
- GRB 041016: Optical limits
- GRB 041016:Optical limit during first minute
- GRB 041015: Optical Observations at Rikubetsu
- GRB041006: Near Infrared observations
- GRB 041016: Optical limit
- GRB041015 : Optical follow-up at Kiso
- GRB041006, optical observation
- GRB 041006: Optical afterglow candidate
- Konus-Wind and Helicon-Coronas-F observations of GRB040924
- GRB040924: KAIT observations
- GRB 040924, optical follow-up
- XRF 040912, identification of CXO sources
- XRF 040916, optical follow-up
- GRB 040912: Optical Observations
- Optical observations of GRB/XRF 040912 = HETE 3557
- GRB040912 : Kiso Optical follow-up observation
- HETE 3557: Optical observations
- GRB040827: analysis of the XMM-Newton observation
- GRB 040827: 2nd epoch of Magellan K-band imaging
- GRB 040827: Detection of NIR afterglow
- GRB 040825: Optical observations
- GRB 040812: Second epoch CXO Observations
- CXO observation of GRB 040812
- GRB 040730, infrared observations
- GRB 040730: Optical observations
- XRF 040701, optical observations
- SGR 1806-20: no IR variability of the proposed counterparts
- SGR 1806-20, potential NIR counterpart
- GRB 040511: NIR observations with REM
- GRB 040511: Optical Observations
- GRB040422 : I-band follow-up observation at Lulin Observatory
- GRB 040403: Optical Observations
- GRB 040323, a dark GRB ?
- GRB 040323: a long GRB detected with INTEGRAL
- GRB040223: Deep NIR NTT data re-analysis
- GRB040228 : KISO optical follow-up observation
- GRB 040223: Deep NIR NTT observations
- GRB 040223 : Optical observation (non-detection)
- GRB 040223: REM IJK Observations
- GRB 040223 XMM-Newton observation ...
- GRB 031203 XMM-Newton observation
- GRB031203: ROSAT upper limits suggest XMM-S1 source as the transient
- XMM-Newton Observation of GRB031203
- GRB 031203: Deep NIR NTT & VLT observations
- XMM-Newton Observation of GRB031203
- GRB 031203: IR NTTobservations do not confirm REM detection
- GRB031203 : Optical Observation of Lulin Observatory
- GRB 031203: z ~ 10 or Fragmented Dust in the Circumburst Environment?