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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. GRB030226: optical observation
  2. IPN triangulation of GRB030225 (annulus)
  3. GRB 030226: Confirmed decay index
  4. GRB030226: ESI spectroscopy
  5. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  6. GRB 030226 simultaneous optical observations
  7. Two absorption systems in GRB 030226
  8. GRB 030226, optical observations
  9. GRB030226: optical observations and refined redshift
  10. GRB030226: Optical decay index
  11. GRB 030226 Optical Spectra and R,I,z' Imaging
  12. GRB 030226, optical observations
  13. GRB 030226: Optical afterglow
  14. GRB030226: Candidate optical afterglow
  15. GRB 030217: Optical Observations at 4, 5, and 6 Days
  16. IPN triangulation of GRB030223 (annulus)
  17. IPN triangulation of GRB030220 (annulus)
  18. GRB: Non-Referencing of GCN Circulars.
  19. IPN triangulation of GRB030218 (annulus)
  20. GRB030217: optical observations
  21. IPN triangulation of GRB030217 (small error box)
  22. IPN triangulation of GRB030215C (annulus)
  23. IPN triangulation of GRB030217 (annulus)
  24. IPN triangulation of GRB030216 (annulus)
  25. IPN triangulation of GRB030215A and GRB030215B (annuli)
  26. GRB030115, WSRT radio observations - correction to GCN 1864
  27. GRB 030131: marginal optical detection
  28. GCN/INTEGRAL Mistake Fixed
  29. GRB030115, WSRT radio observations
  30. IPN triangulation of GRB030206 (annulus)
  31. IPN triangulation of GRB030208 (annulus)
  32. GRB 030204: Optical Observations
  33. GRB030204 field photometry
  34. GRB020819: Kiso R and I band observations
  35. GRB 030204: Correction to GCN 1856
  36. GRB030131: Candidate Optical Afterglow
  37. GRB 030115: Optical Observations
  38. GRB 030204, optical observations
  39. IPN triangulation of GRB030204 (small error box)
  40. IPN triangulation of GRB030202 (annulus)
  41. GRB 030131, optical observations
  42. GRB030131: Kiso optical limit for corrected position
  43. GRB030131: Optical limits for corrected position
  44. GRB 030131: afterglow candidate
  45. GRB 030115, late-time optical observations
  46. GRB030131: corrected INTEGRAL position
  47. Type Ic SN2003L (SN/GRB?), optical spectrum
  48. GRB030131: Kiso Observations
  49. GRB 020819: Host galaxy at Radio Position
  50. IPN triangulation of GRB030131 - CORRECTION
  51. GRB 020819: afterglow candidate
  52. IPN triangulation of GRB030131
  53. GRB030131: Optical limit
  54. GRB 030131 optical observations
  55. GRB030131: refined position
  56. GRB 030131 optical observations
  57. A long GRB detected by INTEGRAL
  58. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  59. Type Ic SN2003L (SN/GRB?) Radio Observations
  60. IPN triangulation of GRB030127 (annulus)
  61. GRB030115 submm upper limit
  62. IPN triangulation of GRB030119 (two large error boxes)
  63. GRB 030115: Further IR observations with IRSF/SIRIUS
  64. IPN triangulation of GRB030117 (two large error boxes)
  65. Publicizing GRB Discoveries - A Message from NASA HQ
  66. GRB 030115: Radio detection of IR candidate
  67. GRB 030115, simultaneous observations by BOOTES-1
  68. GRB 030115: IR observations with IRSF/SIRIUS
  69. IPN triangulation of GRB030115C (large error box)
  70. GRB030115: R-band counterpart of IR candidate
  71. GRB030115, afterglow candidate
  72. GRB 021211: R-band observations at late-time
  73. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  74. IPN triangulation of GRB030115B (small error box)
  75. GRB 030115 : Possible IR counterpart
  76. GRB 030115: Radio Observations
  77. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  78. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  79. IPN triangulation of GRB030115B (annulus)
  80. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  81. Distribution of INTEGRAL SPI-ACS triggers
  82. GRB030115: R-band observations at Asiago
  83. GRB030115: TAROT optical observations
  84. GRB 021211: VLT spectrum
  85. GRB 030115: APO Optical Observations
  86. GRB 030115, no optical candidate
  87. GRB 030115, optical observations
  88. GRB 030115, optical candidate
  89. Possible GRB030113 seen by SPI ACS
  90. Probable GRB030112B seen by SPI ACS
  91. Probable GRB030112 seen by SPI ACS
  92. Information about where HETE will be pointing
  93. Possible GRB030111 seen by SPI ACS
  94. Possible GRB030110b seen by SPI ACS
  95. Possible GRB 030110 seen by SPI ACS
  96. IPN triangulation of GRB030109 (annulus)
  97. IPN triangulation of GRB030105 (large error box)
  98. IPN triangulation of GRB030102B (refined localization - portion of annulus)
  99. Possible GRB 20030109 seen by SPI ACS
  100. IPN triangulation of GRB030102A - correction to peak flux

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