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

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