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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. IPN triangulation of GRB030217 (small error box)
  2. IPN triangulation of GRB030215C (annulus)
  3. IPN triangulation of GRB030217 (annulus)
  4. IPN triangulation of GRB030216 (annulus)
  5. IPN triangulation of GRB030215A and GRB030215B (annuli)
  6. GRB030115, WSRT radio observations - correction to GCN 1864
  7. GRB 030131: marginal optical detection
  8. GCN/INTEGRAL Mistake Fixed
  9. GRB030115, WSRT radio observations
  10. IPN triangulation of GRB030206 (annulus)
  11. IPN triangulation of GRB030208 (annulus)
  12. GRB 030204: Optical Observations
  13. GRB030204 field photometry
  14. GRB020819: Kiso R and I band observations
  15. GRB 030204: Correction to GCN 1856
  16. GRB030131: Candidate Optical Afterglow
  17. GRB 030115: Optical Observations
  18. GRB 030204, optical observations
  19. IPN triangulation of GRB030204 (small error box)
  20. IPN triangulation of GRB030202 (annulus)
  21. GRB 030131, optical observations
  22. GRB030131: Kiso optical limit for corrected position
  23. GRB030131: Optical limits for corrected position
  24. GRB 030131: afterglow candidate
  25. GRB 030115, late-time optical observations
  26. GRB030131: corrected INTEGRAL position
  27. Type Ic SN2003L (SN/GRB?), optical spectrum
  28. GRB030131: Kiso Observations
  29. GRB 020819: Host galaxy at Radio Position
  30. IPN triangulation of GRB030131 - CORRECTION
  31. GRB 020819: afterglow candidate
  32. IPN triangulation of GRB030131
  33. GRB030131: Optical limit
  34. GRB 030131 optical observations
  35. GRB030131: refined position
  36. GRB 030131 optical observations
  37. A long GRB detected by INTEGRAL
  38. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  39. Type Ic SN2003L (SN/GRB?) Radio Observations
  40. IPN triangulation of GRB030127 (annulus)
  41. GRB030115 submm upper limit
  42. IPN triangulation of GRB030119 (two large error boxes)
  43. GRB 030115: Further IR observations with IRSF/SIRIUS
  44. IPN triangulation of GRB030117 (two large error boxes)
  45. Publicizing GRB Discoveries - A Message from NASA HQ
  46. GRB 030115: Radio detection of IR candidate
  47. GRB 030115, simultaneous observations by BOOTES-1
  48. GRB 030115: IR observations with IRSF/SIRIUS
  49. IPN triangulation of GRB030115C (large error box)
  50. GRB030115: R-band counterpart of IR candidate
  51. GRB030115, afterglow candidate
  52. GRB 021211: R-band observations at late-time
  53. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  54. IPN triangulation of GRB030115B (small error box)
  55. GRB 030115 : Possible IR counterpart
  56. GRB 030115: Radio Observations
  57. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  58. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  59. IPN triangulation of GRB030115B (annulus)
  60. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  61. Distribution of INTEGRAL SPI-ACS triggers
  62. GRB030115: R-band observations at Asiago
  63. GRB030115: TAROT optical observations
  64. GRB 021211: VLT spectrum
  65. GRB 030115: APO Optical Observations
  66. GRB 030115, no optical candidate
  67. GRB 030115, optical observations
  68. GRB 030115, optical candidate
  69. Possible GRB030113 seen by SPI ACS
  70. Probable GRB030112B seen by SPI ACS
  71. Probable GRB030112 seen by SPI ACS
  72. Information about where HETE will be pointing
  73. Possible GRB030111 seen by SPI ACS
  74. Possible GRB030110b seen by SPI ACS
  75. Possible GRB 030110 seen by SPI ACS
  76. IPN triangulation of GRB030109 (annulus)
  77. IPN triangulation of GRB030105 (large error box)
  78. IPN triangulation of GRB030102B (refined localization - portion of annulus)
  79. Possible GRB 20030109 seen by SPI ACS
  80. IPN triangulation of GRB030102A - correction to peak flux
  81. IPN triangulation of GRB030102B (portion of annulus)
  82. IPN triangulation of GRB030102A (large error box)
  83. Coronas-F -Wind triangulation of GRB030102
  84. Possible GRB20030107 seen by SPI-ACS
  85. Possible GRB 20030105 seen by SPI ACS
  86. IPN triangulation of GRB030102 (annulus)
  87. GRB on 20030102 seen by SPI-ACS
  88. VLT spectroscopy of the probable host of GRB 021211
  89. GRB on 20030101 seen by SPI-ACS
  90. IPN triangulation of GRB030101 (two large error boxes)
  91. GRB021226
  92. GRB 021211: Probable Host and Underlying Supernova
  93. GRB 021226 registration by Helicon/Coronas-F
  94. Probable GRB in INTEGRAL SPI-ACS
  95. IPN triangulation of GRB021223 (two large error boxes)
  96. GRB021211, radio observations
  97. GRB 021112: Evidence for Another Dark Optical Afterglow
  98. GRB 021219: OSN optical observations
  99. GRB021219: Radio Observations
  100. GRB021219, optical observations

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