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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 GRB030223 (annulus)
  2. IPN triangulation of GRB030220 (annulus)
  3. GRB: Non-Referencing of GCN Circulars.
  4. IPN triangulation of GRB030218 (annulus)
  5. GRB030217: optical observations
  6. IPN triangulation of GRB030217 (small error box)
  7. IPN triangulation of GRB030215C (annulus)
  8. IPN triangulation of GRB030217 (annulus)
  9. IPN triangulation of GRB030216 (annulus)
  10. IPN triangulation of GRB030215A and GRB030215B (annuli)
  11. GRB030115, WSRT radio observations - correction to GCN 1864
  12. GRB 030131: marginal optical detection
  13. GCN/INTEGRAL Mistake Fixed
  14. GRB030115, WSRT radio observations
  15. IPN triangulation of GRB030206 (annulus)
  16. IPN triangulation of GRB030208 (annulus)
  17. GRB 030204: Optical Observations
  18. GRB030204 field photometry
  19. GRB020819: Kiso R and I band observations
  20. GRB 030204: Correction to GCN 1856
  21. GRB030131: Candidate Optical Afterglow
  22. GRB 030115: Optical Observations
  23. GRB 030204, optical observations
  24. IPN triangulation of GRB030204 (small error box)
  25. IPN triangulation of GRB030202 (annulus)
  26. GRB 030131, optical observations
  27. GRB030131: Kiso optical limit for corrected position
  28. GRB030131: Optical limits for corrected position
  29. GRB 030131: afterglow candidate
  30. GRB 030115, late-time optical observations
  31. GRB030131: corrected INTEGRAL position
  32. Type Ic SN2003L (SN/GRB?), optical spectrum
  33. GRB030131: Kiso Observations
  34. GRB 020819: Host galaxy at Radio Position
  35. IPN triangulation of GRB030131 - CORRECTION
  36. GRB 020819: afterglow candidate
  37. IPN triangulation of GRB030131
  38. GRB030131: Optical limit
  39. GRB 030131 optical observations
  40. GRB030131: refined position
  41. GRB 030131 optical observations
  42. A long GRB detected by INTEGRAL
  43. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  44. Type Ic SN2003L (SN/GRB?) Radio Observations
  45. IPN triangulation of GRB030127 (annulus)
  46. GRB030115 submm upper limit
  47. IPN triangulation of GRB030119 (two large error boxes)
  48. GRB 030115: Further IR observations with IRSF/SIRIUS
  49. IPN triangulation of GRB030117 (two large error boxes)
  50. Publicizing GRB Discoveries - A Message from NASA HQ
  51. GRB 030115: Radio detection of IR candidate
  52. GRB 030115, simultaneous observations by BOOTES-1
  53. GRB 030115: IR observations with IRSF/SIRIUS
  54. IPN triangulation of GRB030115C (large error box)
  55. GRB030115: R-band counterpart of IR candidate
  56. GRB030115, afterglow candidate
  57. GRB 021211: R-band observations at late-time
  58. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  59. IPN triangulation of GRB030115B (small error box)
  60. GRB 030115 : Possible IR counterpart
  61. GRB 030115: Radio Observations
  62. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  63. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  64. IPN triangulation of GRB030115B (annulus)
  65. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  66. Distribution of INTEGRAL SPI-ACS triggers
  67. GRB030115: R-band observations at Asiago
  68. GRB030115: TAROT optical observations
  69. GRB 021211: VLT spectrum
  70. GRB 030115: APO Optical Observations
  71. GRB 030115, no optical candidate
  72. GRB 030115, optical observations
  73. GRB 030115, optical candidate
  74. Possible GRB030113 seen by SPI ACS
  75. Probable GRB030112B seen by SPI ACS
  76. Probable GRB030112 seen by SPI ACS
  77. Information about where HETE will be pointing
  78. Possible GRB030111 seen by SPI ACS
  79. Possible GRB030110b seen by SPI ACS
  80. Possible GRB 030110 seen by SPI ACS
  81. IPN triangulation of GRB030109 (annulus)
  82. IPN triangulation of GRB030105 (large error box)
  83. IPN triangulation of GRB030102B (refined localization - portion of annulus)
  84. Possible GRB 20030109 seen by SPI ACS
  85. IPN triangulation of GRB030102A - correction to peak flux
  86. IPN triangulation of GRB030102B (portion of annulus)
  87. IPN triangulation of GRB030102A (large error box)
  88. Coronas-F -Wind triangulation of GRB030102
  89. Possible GRB20030107 seen by SPI-ACS
  90. Possible GRB 20030105 seen by SPI ACS
  91. IPN triangulation of GRB030102 (annulus)
  92. GRB on 20030102 seen by SPI-ACS
  93. VLT spectroscopy of the probable host of GRB 021211
  94. GRB on 20030101 seen by SPI-ACS
  95. IPN triangulation of GRB030101 (two large error boxes)
  96. GRB021226
  97. GRB 021211: Probable Host and Underlying Supernova
  98. GRB 021226 registration by Helicon/Coronas-F
  99. Probable GRB in INTEGRAL SPI-ACS
  100. IPN triangulation of GRB021223 (two large error boxes)

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