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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"

32698 results found.

  1. GRB030115, WSRT radio observations
  2. IPN triangulation of GRB030206 (annulus)
  3. IPN triangulation of GRB030208 (annulus)
  4. GRB 030204: Optical Observations
  5. GRB030204 field photometry
  6. GRB020819: Kiso R and I band observations
  7. GRB 030204: Correction to GCN 1856
  8. GRB 030115: Optical Observations
  9. GRB 030204, optical observations
  10. IPN triangulation of GRB030204 (small error box)
  11. IPN triangulation of GRB030202 (annulus)
  12. GRB 030131, optical observations
  13. GRB030131: Kiso optical limit for corrected position
  14. GRB030131: Optical limits for corrected position
  15. GRB 030131: afterglow candidate
  16. GRB 030115, late-time optical observations
  17. GRB030131: corrected INTEGRAL position
  18. Type Ic SN2003L (SN/GRB?), optical spectrum
  19. GRB030131: Kiso Observations
  20. GRB 020819: Host galaxy at Radio Position
  21. IPN triangulation of GRB030131 - CORRECTION
  22. GRB 020819: afterglow candidate
  23. IPN triangulation of GRB030131
  24. GRB 030131 optical observations
  25. GRB 030131 optical observations
  26. A long GRB detected by INTEGRAL
  27. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  28. Type Ic SN2003L (SN/GRB?) Radio Observations
  29. IPN triangulation of GRB030127 (annulus)
  30. GRB030115 submm upper limit
  31. IPN triangulation of GRB030119 (two large error boxes)
  32. GRB 030115: Further IR observations with IRSF/SIRIUS
  33. IPN triangulation of GRB030117 (two large error boxes)
  34. Publicizing GRB Discoveries - A Message from NASA HQ
  35. GRB 030115: Radio detection of IR candidate
  36. GRB 030115, simultaneous observations by BOOTES-1
  37. GRB 030115: IR observations with IRSF/SIRIUS
  38. IPN triangulation of GRB030115C (large error box)
  39. GRB030115: R-band counterpart of IR candidate
  40. GRB030115, afterglow candidate
  41. GRB 021211: R-band observations at late-time
  42. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  43. IPN triangulation of GRB030115B (small error box)
  44. GRB 030115 : Possible IR counterpart
  45. GRB 030115: Radio Observations
  46. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  47. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  48. IPN triangulation of GRB030115B (annulus)
  49. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  50. Distribution of INTEGRAL SPI-ACS triggers
  51. GRB030115: R-band observations at Asiago
  52. GRB030115: TAROT optical observations
  53. GRB 021211: VLT spectrum
  54. GRB 030115: APO Optical Observations
  55. GRB 030115, no optical candidate
  56. GRB 030115, optical observations
  57. GRB 030115, optical candidate
  58. Possible GRB030113 seen by SPI ACS
  59. Probable GRB030112B seen by SPI ACS
  60. Probable GRB030112 seen by SPI ACS
  61. Possible GRB030111 seen by SPI ACS
  62. Possible GRB030110b seen by SPI ACS
  63. Possible GRB 030110 seen by SPI ACS
  64. IPN triangulation of GRB030109 (annulus)
  65. IPN triangulation of GRB030105 (large error box)
  66. IPN triangulation of GRB030102B (refined localization - portion of annulus)
  67. Possible GRB 20030109 seen by SPI ACS
  68. IPN triangulation of GRB030102B (portion of annulus)
  69. IPN triangulation of GRB030102A (large error box)
  70. Possible GRB20030107 seen by SPI-ACS
  71. Possible GRB 20030105 seen by SPI ACS
  72. IPN triangulation of GRB030102 (annulus)
  73. GRB on 20030102 seen by SPI-ACS
  74. VLT spectroscopy of the probable host of GRB 021211
  75. GRB on 20030101 seen by SPI-ACS
  76. IPN triangulation of GRB030101 (two large error boxes)
  77. GRB021226
  78. GRB 021211: Probable Host and Underlying Supernova
  79. GRB 021226 registration by Helicon/Coronas-F
  80. Probable GRB in INTEGRAL SPI-ACS
  81. IPN triangulation of GRB021223 (two large error boxes)
  82. GRB021211, radio observations
  83. GRB 021112: Evidence for Another Dark Optical Afterglow
  84. GRB 021219: OSN optical observations
  85. GRB021219: Radio Observations
  86. IPN triangulation of GRB021219 - CORRECTION
  87. IPN triangulation of GRB021219
  88. GRB021219, optical observation by MASTER
  89. GRB021219: Correction to GCN 1766
  90. VLT spectra of GRB 021211 revisited
  91. GRB021219: a long GRB localized by INTEGRAL
  92. IPN detection of continued activity from SGR1806-20
  93. IPN triangulation of GRB021215 (large error box)
  94. IPN triangulation of GRB021214 (annulus)
  95. XRF 020903 : HST observations
  96. GRB 021201: Optical Observations
  97. GRB 021211, optical observations
  98. GRB 021211: CTIO observations
  99. GRB021211: Measurement of Early Time Afterglow
  100. VLT spectrum of GRB 021211

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