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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"

35431 results found.

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

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