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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"

32537 results found.

  1. GRB020322, optical observations
  2. GRB 020322: Optical candidate
  3. XMM-Newton observation of GRB020322
  4. GRB020322: Optical Observations
  5. GRB 020321: Optical observations
  6. GRB 011121: Fourth Epoch of HST Imaging
  7. GRB020317: optical observations
  8. GRB020321 optical observations
  9. GRB020305: NIR observations
  10. GRB 020317 : KISO Optical Observations
  11. GRB020317 (=H1959): Localization by HETE of a Low Fluence GRB
  12. GRB 020305: Optical Observations
  13. GRB020317, optical observations
  14. GRB 011121: Third HST Epoch
  15. GRB020305: Properties of the Candidate Optical Afterglow
  16. GRB 011121: HST Observations reveal an intermediate-time multicolor
  17. GRB011121, possible supernova association
  18. GRB011130 (XRF011130) Second Epoch Chandra Observations
  19. GRB020305: Subaru Optical Observations
  20. GRB 020305: Optical observations
  21. XRF/GRB 011030 Images
  22. XRF/GRB 011030: Detection of the Probable Host Galaxy
  23. GRB 020305: Candidate optical afterglow
  24. Type Ic SN2002bl (SN/GRB?) Radio Observations
  25. GRB020305 (=H1939): Localization of a GRB by HETE
  26. HST Imaging of the afterglow and host of GRB 011121
  27. GRB 010921: HST Observations
  28. GRB020127: Further VLA Observations of Possible Counterparts
  29. IPN detection of further SGR1900+14 activity
  30. SGR1900+14 activity
  31. GRB020124 BVRI field photometry
  32. GRB020127: Palomar and VLA Observations of Possible Counterparts
  33. GRB020127, WSRT radio observations
  34. GRB020127 Optical Observations
  35. SN2002ap (SN/GRB?) UBVRI Field Photometry
  36. GRB020127: Chandra Observations and Prospective Counterparts
  37. pre-SN2002ap (SN/GRB?) imaging of M74
  38. Type Ib/c SN2002ap (SN/GRB?)
  39. GRB020127: Optical observations
  40. GRB 020127, I-band observations starting 3.14-hr after the event
  41. IPN triangulation of GRB020127 (=H1902)
  42. GRB020127 Optical Observations -- Erratum to GCN 1230
  43. GRB010921 Optical Observations
  44. GRB020127(=H1902): Localization of a Double-Peaked GRB by HETE
  45. GRB020124: Optical observations
  46. VLT observations of GRB 020124: The fading optical/near-infrared afterglow
  47. GRB020124: Optical observations
  48. GRB 020124: Optical observations
  49. GRB 020124 Optical Observations
  50. IPN triangulation of GRB020124 (HETE 1896)
  51. GRB 020124: Optical afterglow
  52. GRB020124(=H1896): Localization of a Long GRB by HETE
  53. GRB optical counterpart candidate in GCN 1217 is M dwarf
  54. GRB011212, Optical Observations
  55. GRB011211: BeppoSAX/GRBM data
  56. Optical polarization observations for GRB011211
  57. Color indices of the afterglow of GRB011211
  58. GRB011212: Optical observations at Gunma
  59. GRB 011211, spectrum and optical photometry
  60. GRB 011130: Optical Observations of X-ray and Radio Sources
  61. GRB 011130, Radio/X-ray Comparison
  62. GRB011212: Optical observations
  63. GRB 011212: optical observation at Asiago
  64. GRB 011211: Evidence for an Optical Break
  65. GRB 011211: TNG Spectroscopic Observations
  66. optical follow-up of GRB(XRF) 011211
  67. GRB 011212: optical observation at Oslo (relayed)
  68. GRB 011211: Optical Spectroscopy
  69. GRB 011211, Optical Observations
  70. GRB011212, BVRI field photometry
  71. GRB011211, BVRI field photometry
  72. GRB011212: Optical observations
  73. GRB 011211: BVRi-band photometry
  74. Fading of the optical source associated of XRF 011211
  75. XMM-Newton observation of GRB011211
  76. GRB 011211 Optical Observations: Likely Afterglow
  77. GRB011130 (=XRF011130): Further analysis of Chandra Target of
  78. GRB 011130: Optical Observations of Chandra Sources
  79. GRB 011130: Optical Observations of Chandra sources
  80. GRB011130 (=XRF011130): Scheduled Target of Opportunity
  81. GRB 011130: Magellan spectroscopy
  82. GRB011130, optical observations
  83. GRB011130, optical observations
  84. GRB011130 (=XRF011130): Second Revised Localization by HETE
  85. GRB 011130 I-band Observation
  86. GRB011130 (XRF011130) optical observations
  87. GRB011130 (XRF011130) SDSS PT i-band observations
  88. XRF011130: Infrared Observations
  89. GRB011130, Radio Observations
  90. Detection of the X-ray afterglow of GRB011121 by BeppoSAX
  91. GRB011130 (=XRF011130), Optical Observations
  92. XRF011130: NEAT Optical Observations
  93. GRB011130 (=XRF011130): Revised Localization of an X-ray
  94. GRB001109, Radio Monitoring
  95. GRB 011121: Errata URL
  96. GRB 011121
  97. GRB 011121: J-band observations
  98. GRB 011121: NIR observations, host galaxy?
  99. GRB010921 - Milagro GeV/TeV Observations
  100. GRB 011121: HST Scheduled

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