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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').
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"

28049 results found.

  1. SGR 1806-20, RHESSI observations of the 041227 giant flare
  2. Third epoch observations of SGR 1806-20 with VLA
  3. Second Epoch VLA observations of SGR 1806-20
  4. Second-epoch VLA observations of SGR 1806-20
  5. SGR1806 VLA Observations
  6. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  7. GRB 041217: Optical observations
  8. GRB041228: Swift-BAT detection of a burst
  9. GRB041219; RXTE ASM Observations
  10. NIR Observations of GRB 041219
  11. GRB041226: Swift-BAT detection of a burst
  12. GRB041223: decay of the afterglow
  13. GRB 041224: near-infrared observations with REM
  14. GRB 041223 Fluence measured by Swift-BAT
  15. GRB041223: optical and NIR observations with REM
  16. Swift-BAT Time History of GRB041219
  17. GRB 041219: TAROT optical observations
  18. GRB 041218: TAROT optical observations
  19. GRB 041223: J-band observations of the afterglow
  20. GRB 041219c: PROMPT Observations
  21. GRB041223: Swift-BAT detection of a bright long burst
  22. GRB 041218: optical observations
  23. GRB 041219 : optical follow-up observations
  24. Deep RAPTOR observations during GRB 041219
  25. GRB 041218 Optical Observations
  26. GRB041219: Continued NIR Observations
  27. GRB 041219 ,optical observation
  28. GRB 041219: Radio Afterglow Detection
  29. GRB 041218 : Radio Observations
  30. GRB 041218: R-band optical observations
  31. GRB041218: optical observations
  32. GRB041219: Confirmed NIR Afterglow
  33. Swift-BAT detection of the bright long burst GRB041219
  34. GRB 041219: Infrared Afterglow Candidate
  35. GRB041219, BVRcIc field calibration
  36. GRB 041219: Infrared Afterglow Candidate
  37. GRB041218, BVRcIc field calibration
  38. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  39. GRB 041219 - A long GRB detected by INTEGRAL
  40. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  41. GRB 041217: PROMPT Observations
  42. GRB 041217: LCO40 Optical Observations and Possible Candidates
  43. GRB 041218 - A long GRB detected by integral
  44. GRB041217: NIR and optical observations with REM
  45. GRB041217: Infrared Observations
  46. GRB041217: The First GRB Located On-Board Swift
  47. GRB041211: Faulkes Telescope continued optical monitoring
  48. Optical Transient in Lynx not a GRB
  49. Optical transient (GRB?) in Lynx
  50. GRB041211: RAPTOR observations
  51. GRB041211: Ashra Prototype optical observation
  52. GRB041211, BVRcIc field calibration
  53. GRB041211,optical observation
  54. GRB 041211: Infrared Observations
  55. GRB 041211: KAIT observations
  56. GRB 041211: Optical follow-up in East Asian region
  57. Triangulation of short GRB 041116 (large error box)
  58. GRB 040924: Afterglow Color
  59. GRB 041006: GETS Optical Afterglow Observation
  60. Summary of the recent bursts from SGR 1806-20
  61. GRB 041006: Optical Observations
  62. GRB041006, late-time optical photometry
  63. GRB041006: RTT150 Optical Observations
  64. HST Observations: XRF 040701 and 040812
  65. Bright bursts from SGR1806-20
  66. GRB 041016: BOOTES-2 simultaneous observation
  67. GRB041006: RTT150 Optical Observations
  68. GRB041016,optical observation
  69. GRB 041016: Optical limits
  70. GRB 041016:Optical limit during first minute
  71. GRB 041015: Optical Observations at Rikubetsu
  72. GRB 041016: Optical limit
  73. GRB 041015 R band observations
  74. GRB040924, BVRcIc field calibration
  75. GRB041015,optical observation
  76. GRB041006: Fading X-ray Afterglow Observed with Chandra
  77. GRB 041015 - A long GRB detected by INTEGRAL
  78. GRB041006: VLT observations of the afterglow and host galaxy
  79. GRB041006: Optical observations and Potential host galaxy
  80. GRB041006, BVRcIc field calibration
  81. GRB 040924: VLT spectroscopy
  82. GRB 041006: SARA afterglow observations
  83. GRB041006, optical observation in CrAO
  84. Search for SN light in XRF 040912 with MEGACAM
  85. GRB 041006: BR observations with VATT
  86. GRB 041006: Redshift confirmed
  87. GRB 041006: Radio Observations
  88. GRB 041006 : optical follow-up observation at Lulin Observatory
  89. GRB041006: Optical photometry and spectroscopy at TNG
  90. GRB 041006: presice astrometry
  91. GRB041006, optical I observation
  92. GRB041006 (=HETE3570): optical observations
  93. ROTSE-IIIa Observations of GRB 041006
  94. GRB041006: MASTER optical observations
  95. GRB041006,optical observation
  96. Konus-Wind observation of a series SGR 1806-20 bursts on 041005
  97. GRB041006: Fading of optical afterglow candidate
  98. GRB 041006: Optical afterglow candidate
  99. Bursts from SGR 1806-20: Preliminary INTEGRAL results
  100. XRF 020903: Observations of the Host Galaxy

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