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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"
  1. BeppoSAX ALERT: possible GRB020411
  2. GRB 020409, optical observations
  3. GRB 020409: Optical Observations
  4. GRB020406(?), optical observations
  5. GRB020410, optical observations
  6. BeppoSAX ALERT: possible GRB020410
  7. X-ray afterglow of GRB020321
  8. BeppoSAX GRB : GRB020409
  9. GRB020331: Confirmation of Afterglow Candidate with Magellan
  10. GRB020405: VLT optical observations and V band decay slope
  11. GRB020331 optical observations with RIMOTS
  12. GRB020124 optical observations with RIBOTS/RIMOTS
  13. GRB 020321: Candidate X-ray Counterparts
  14. ASM GRB candidate 020406 refined error box
  15. GRB 020405: Moderate-resolution spectroscopy
  16. GRB020331: Optical Observations of Afterglow Candidate
  17. GRB020406(?), optical observations
  18. GRB020405: VLT optical observations
  19. Revised Photometry of the Optical Afterglow of GRB 020405
  20. GRB020405: OT observations
  21. GRB 020331: Candidate Optical Afterglow
  22. GRB 020405: Decay index
  23. Short RXTE/ASM transient 020406; may be a GRB
  24. GRB020405, Radio Observations
  25. GRB020405: VLT spectroscopy
  26. Fading Optical Afterglow and Possible Host Galaxy of GRB 020405
  27. V band observations of GRB020405
  28. GRB 020405, U-band observations
  29. GRB 020405: Optical afterglow candidate
  30. IPN localization of GRB020405
  31. GRB011212: Optical Observations
  32. GRB 020331: NIR Observations
  33. GRB 020331: NIR Observations
  34. GRB020331 NIR observation at KPNO (re-submission)
  35. GRB02033 NIR observation at KPNO
  36. GRB020331 field photometry
  37. GRB 020331 Optical Observations
  38. GRB 020331, NIR observations
  39. GRB 020331: Optical observations
  40. GRB020331(=H1963): The "Easter" Burst Detected by HETE
  41. GRB 020321: Infrared observations
  42. GRB 020322: BeppoSAX observations of the X-ray afterglow
  43. SN 2002ap - peak brightness date (SN/GRB?)
  44. GRB011211: HST Observations of Optical Afterglow and Host Galaxy
  45. GRB 020322, Radio observations
  46. Near-Infrared Observations of GRB020322 at TIRGO
  47. GRB 020321, Radio Observations
  48. GRB 020322: Optical Observations
  49. GRB020127: Proposed Host Galaxy Detection and Identification of Afterglow
  50. GRB 020321: Optical observations
  51. GRB020317 BVRI field photometry
  52. GRB011211 revised BVRI field photometry
  53. GRB020305 BVRI field photometry
  54. GRB020322 BVRI field photometry
  55. GRB 020322 optical observations
  56. GRB020322: Candidate Optical Afterglow
  57. GRB 020322 optical observation
  58. GRB020317 : Near IR Observations from Mt Abu Observatory
  59. GRB 020322: Optical Sources and Improved Astrometry
  60. GRB020322, optical observations
  61. GRB 020322: Optical candidate
  62. XMM-Newton observation of GRB020322
  63. GRB020322: Optical Observations
  64. GRB020322: BeppoSAX/NFI Observations
  65. Bepposax GRB020322 The second springtime BSAX GRB
  66. GRB 020321: Optical observations
  67. GRB 011121: Fourth Epoch of HST Imaging
  68. GRB020317: optical observations
  69. GRB020321 optical observations
  70. GRB020321: BeppoSAX/NFI Observations
  71. GRB020321: a faint BeppoSAX detection
  72. GRB020305: NIR observations
  73. GRB 020317 : KISO Optical Observations
  74. BeppoSAX ALERT: GRB020321, the "Springtime Burst"
  75. GRB020317 (=H1959): Localization by HETE of a Low Fluence GRB
  76. GRB 020305: Optical Observations
  77. GRB020317, optical observations
  78. GRB 020317: Optical observations
  79. GRB 011121: Third HST Epoch
  80. GRB020305: Properties of the Candidate Optical Afterglow
  81. GRB 011121: HST Observations reveal an intermediate-time multicolor
  82. GRB011121, possible supernova association
  83. GRB011130 (XRF011130) Second Epoch Chandra Observations
  84. GRB020305: Subaru Optical Observations
  85. GRB 020305: Optical observations
  86. XRF/GRB 011030 Images
  87. XRF/GRB 011030: Detection of the Probable Host Galaxy
  88. GRB 020305: Candidate optical afterglow
  89. Type Ic SN2002bl (SN/GRB?) Radio Observations
  90. GRB020305, optical observations
  91. GRB020305: Optical Observations
  92. IPN triangulation of GRB020305 (HETE 1939)
  93. GRB020305 (=H1939): Localization of a GRB by HETE
  94. GRB 020305: Optical observations
  95. HST Imaging of the afterglow and host of GRB 011121
  96. GRB 010921: HST Observations
  97. IPN detection and localization of Cygnus X-1 flares
  98. GRB020127: Further VLA Observations of Possible Counterparts
  99. RXTE Observations of SGR 1900+14
  100. IPN detection of further SGR1900+14 activity

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