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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"

37524 results found.

  1. GRB 030227: fading of candidate optical afterglow 'S1-A'
  2. GRB030227:Optical observations
  3. GRB 20030226: Upper limits from recent and historical observations
  4. GRB 030227, possible optical counterpart of XMM-Newton source
  5. GRB030227 - faint tentative OT candidate
  6. GRB 030226, optical observations
  7. GRB030227: Kiso optical observations
  8. GRB 030227: Kyoto optical observation
  9. GRB 030226, optical light curve
  10. GRB 030226 spectroscopy
  11. Possible break in the GRB 030226 light curve
  12. GRB 030226 : Predicted light curve
  13. IPN triangulation of GRB030225 (annulus)
  14. GRB 030226: Confirmed decay index
  15. GRB030226: ESI spectroscopy
  16. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  17. GRB 030226 simultaneous optical observations
  18. Two absorption systems in GRB 030226
  19. GRB 030226, optical observations
  20. GRB 030226 Optical Spectra and R,I,z' Imaging
  21. GRB 030226, optical observations
  22. GRB 030226: Optical afterglow
  23. GRB 030217: Optical Observations at 4, 5, and 6 Days
  24. IPN triangulation of GRB030223 (annulus)
  25. IPN triangulation of GRB030220 (annulus)
  26. GRB: Non-Referencing of GCN Circulars.
  27. IPN triangulation of GRB030218 (annulus)
  28. IPN triangulation of GRB030217 (small error box)
  29. IPN triangulation of GRB030215C (annulus)
  30. IPN triangulation of GRB030217 (annulus)
  31. IPN triangulation of GRB030216 (annulus)
  32. IPN triangulation of GRB030215A and GRB030215B (annuli)
  33. GRB030115, WSRT radio observations - correction to GCN 1864
  34. GRB 030131: marginal optical detection
  35. GRB030115, WSRT radio observations
  36. IPN triangulation of GRB030206 (annulus)
  37. IPN triangulation of GRB030208 (annulus)
  38. GRB 030204: Optical Observations
  39. GRB030204 field photometry
  40. GRB020819: Kiso R and I band observations
  41. GRB 030204: Correction to GCN 1856
  42. GRB 030115: Optical Observations
  43. GRB 030204, optical observations
  44. IPN triangulation of GRB030204 (small error box)
  45. IPN triangulation of GRB030202 (annulus)
  46. GRB 030131, optical observations
  47. GRB030131: Kiso optical limit for corrected position
  48. GRB030131: Optical limits for corrected position
  49. GRB 030131: afterglow candidate
  50. GRB 030115, late-time optical observations
  51. GRB030131: corrected INTEGRAL position
  52. Type Ic SN2003L (SN/GRB?), optical spectrum
  53. GRB030131: Kiso Observations
  54. GRB 020819: Host galaxy at Radio Position
  55. IPN triangulation of GRB030131 - CORRECTION
  56. GRB 020819: afterglow candidate
  57. IPN triangulation of GRB030131
  58. GRB 030131 optical observations
  59. GRB 030131 optical observations
  60. A long GRB detected by INTEGRAL
  61. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  62. Type Ic SN2003L (SN/GRB?) Radio Observations
  63. IPN triangulation of GRB030127 (annulus)
  64. GRB030115 submm upper limit
  65. IPN triangulation of GRB030119 (two large error boxes)
  66. GRB 030115: Further IR observations with IRSF/SIRIUS
  67. IPN triangulation of GRB030117 (two large error boxes)
  68. Publicizing GRB Discoveries - A Message from NASA HQ
  69. GRB 030115: Radio detection of IR candidate
  70. GRB 030115, simultaneous observations by BOOTES-1
  71. GRB 030115: IR observations with IRSF/SIRIUS
  72. IPN triangulation of GRB030115C (large error box)
  73. GRB030115: R-band counterpart of IR candidate
  74. GRB030115, afterglow candidate
  75. GRB 021211: R-band observations at late-time
  76. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  77. IPN triangulation of GRB030115B (small error box)
  78. GRB 030115 : Possible IR counterpart
  79. GRB 030115: Radio Observations
  80. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  81. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  82. IPN triangulation of GRB030115B (annulus)
  83. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  84. Distribution of INTEGRAL SPI-ACS triggers
  85. GRB030115: R-band observations at Asiago
  86. GRB030115: TAROT optical observations
  87. GRB 021211: VLT spectrum
  88. GRB 030115: APO Optical Observations
  89. GRB 030115, no optical candidate
  90. GRB 030115, optical observations
  91. GRB 030115, optical candidate
  92. Possible GRB030113 seen by SPI ACS
  93. Probable GRB030112B seen by SPI ACS
  94. Probable GRB030112 seen by SPI ACS
  95. Possible GRB030111 seen by SPI ACS
  96. Possible GRB030110b seen by SPI ACS
  97. Possible GRB 030110 seen by SPI ACS
  98. IPN triangulation of GRB030109 (annulus)
  99. IPN triangulation of GRB030105 (large error box)
  100. IPN triangulation of GRB030102B (refined localization - portion of annulus)

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