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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. GRB 020525: Optical Observations
  2. GRB020525, optical observations
  3. IPN detection of possible bursts from SGR1806-20
  4. IPN triangulation of GRB020525
  5. XRF 020427: Sudden Ionospheric Disturbance (SID)
  6. HETE Observations of GX354-0 (= MXB1728-34, so-called "Slow
  7. XRF020427: Chandra Identification of a Likely X-ray Counterpart
  8. IPN triangulation of a burst from SGR1806-20
  9. GRB/XRF 020427, Radio Observations
  10. HST detection of the likely host galaxy of GRB 020124
  11. GRB020405 field photometry at ESO
  12. XRF020427: Chandra Observations and Candidate X-ray Counterparts
  13. GRB(XRF) 020427: X-ray afterglow with BeppoSAX
  14. GRB020321 : Optical observations.
  15. GRB020427 BeppoSAX NFI Observation
  16. XRF 020427
  17. GRB020331: Third Epoch and Revised Second Epoch Optical
  18. The end of BSAX GRB activities
  19. GRB 020410, Radio Observations
  20. GRB 020418: Optical observations
  21. GRB 020124: Optical observations
  22. GRB 020418: Optical observations
  23. IPN triangulation of GRB020418
  24. GRB020405: VLT observations of the OT environment
  25. GRB020410: BeppoSAX NFI observations refined analysis
  26. GRB 020409: Optical Observations
  27. Mars Odyssey joins the IPN
  28. IPN triangulation of GRB020413
  29. GRB 020409, 2-nd epoch optical observations at Terskol.
  30. GRB020405: predicted break
  31. GRB 020409: Optical observations
  32. GRB 020409, No Optical Detection to R = 22
  33. GRB020410: second BeppoSAX NFI observation
  34. GRB 020409: No Evidence for an Optical Afterglow
  35. GRB 020409, 2nd epoch optical observations
  36. GRB 020331 Kyoto observation on March 31
  37. GRB 020409
  38. GRB 020409 SARA Observations
  39. GRB "020411"
  40. GRB 020409, No Optical Detection to R = 20
  41. GRB020410: BeppoSAX NFI observation
  42. GRB 020409: Optical observations
  43. April 11 BeppoSAX event (GRB020411) is likely not a GRB
  44. GRB 020410, optical observations
  45. BeppoSAX ALERT: possible GRB020411
  46. GRB 020409, optical observations
  47. GRB 020409: Optical Observations
  48. GRB020406(?), optical observations
  49. GRB020410, optical observations
  50. BeppoSAX ALERT: possible GRB020410
  51. X-ray afterglow of GRB020321
  52. BeppoSAX GRB : GRB020409
  53. GRB020331: Confirmation of Afterglow Candidate with Magellan
  54. GRB020405: VLT optical observations and V band decay slope
  55. GRB020331 optical observations with RIMOTS
  56. GRB020124 optical observations with RIBOTS/RIMOTS
  57. GRB 020321: Candidate X-ray Counterparts
  58. ASM GRB candidate 020406 refined error box
  59. GRB 020405: Moderate-resolution spectroscopy
  60. GRB020331: Optical Observations of Afterglow Candidate
  61. GRB020406(?), optical observations
  62. GRB020405: VLT optical observations
  63. Revised Photometry of the Optical Afterglow of GRB 020405
  64. GRB020405: OT observations
  65. GRB 020331: Candidate Optical Afterglow
  66. GRB 020405: Decay index
  67. Short RXTE/ASM transient 020406; may be a GRB
  68. GRB020405, Radio Observations
  69. GRB020405: VLT spectroscopy
  70. Fading Optical Afterglow and Possible Host Galaxy of GRB 020405
  71. V band observations of GRB020405
  72. GRB 020405, U-band observations
  73. GRB 020405: Optical afterglow candidate
  74. IPN localization of GRB020405
  75. GRB011212: Optical Observations
  76. GRB 020331: NIR Observations
  77. GRB 020331: NIR Observations
  78. GRB020331 NIR observation at KPNO (re-submission)
  79. GRB02033 NIR observation at KPNO
  80. GRB020331 field photometry
  81. GRB 020331 Optical Observations
  82. GRB 020331, NIR observations
  83. GRB 020331: Optical observations
  84. GRB020331(=H1963): The "Easter" Burst Detected by HETE
  85. GRB 020321: Infrared observations
  86. GRB 020322: BeppoSAX observations of the X-ray afterglow
  87. SN 2002ap - peak brightness date (SN/GRB?)
  88. GRB011211: HST Observations of Optical Afterglow and Host Galaxy
  89. GRB 020322, Radio observations
  90. Near-Infrared Observations of GRB020322 at TIRGO
  91. GRB 020321, Radio Observations
  92. GRB 020322: Optical Observations
  93. GRB020127: Proposed Host Galaxy Detection and Identification of Afterglow
  94. GRB 020321: Optical observations
  95. GRB020317 BVRI field photometry
  96. GRB011211 revised BVRI field photometry
  97. GRB020305 BVRI field photometry
  98. GRB020322 BVRI field photometry
  99. GRB 020322 optical observations
  100. GRB020322: Candidate Optical Afterglow

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