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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"

26299 results found.

  1. GRB020819: Kiso R and I band observations
  2. GRB030131: Candidate Optical Afterglow
  3. IPN triangulation of GRB030204 (small error box)
  4. IPN triangulation of GRB030202 (annulus)
  5. GRB 030131, optical observations
  6. GRB030131: Optical limits for corrected position
  7. GRB 030115, late-time optical observations
  8. GRB030131: corrected INTEGRAL position
  9. GRB030131: Kiso Observations
  10. GRB 020819: Host galaxy at Radio Position
  11. IPN triangulation of GRB030131
  12. GRB030131: Optical limit
  13. GRB030131: refined position
  14. A long GRB detected by INTEGRAL
  15. IPN triangulation of GRB030127 (annulus)
  16. Publicizing GRB Discoveries - A Message from NASA HQ
  17. GRB 030115: Radio detection of IR candidate
  18. GRB 030115, simultaneous observations by BOOTES-1
  19. GRB 030115: IR observations with IRSF/SIRIUS
  20. IPN triangulation of GRB030115C (large error box)
  21. GRB030115: R-band counterpart of IR candidate
  22. GRB030115, afterglow candidate
  23. GRB 021211: R-band observations at late-time
  24. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  25. IPN triangulation of GRB030115B (annulus)
  26. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  27. GRB030115: TAROT optical observations
  28. GRB 021211: VLT spectrum
  29. GRB 030115, optical observations
  30. GRB 030115, optical candidate
  31. Possible GRB030113 seen by SPI ACS
  32. Probable GRB030112B seen by SPI ACS
  33. Probable GRB030112 seen by SPI ACS
  34. Information about where HETE will be pointing
  35. Possible GRB030111 seen by SPI ACS
  36. Possible GRB030110b seen by SPI ACS
  37. Possible GRB 030110 seen by SPI ACS
  38. IPN triangulation of GRB030109 (annulus)
  39. IPN triangulation of GRB030105 (large error box)
  40. Possible GRB 20030109 seen by SPI ACS
  41. IPN triangulation of GRB030102B (portion of annulus)
  42. IPN triangulation of GRB030102A (large error box)
  43. Possible GRB20030107 seen by SPI-ACS
  44. Possible GRB 20030105 seen by SPI ACS
  45. IPN triangulation of GRB030102 (annulus)
  46. GRB on 20030102 seen by SPI-ACS
  47. VLT spectroscopy of the probable host of GRB 021211
  48. GRB on 20030101 seen by SPI-ACS
  49. IPN triangulation of GRB030101 (two large error boxes)
  50. GRB021226
  51. GRB 021211: Probable Host and Underlying Supernova
  52. GRB 021226 registration by Helicon/Coronas-F
  53. IPN triangulation of GRB021223 (two large error boxes)
  54. GRB 021112: Evidence for Another Dark Optical Afterglow
  55. GRB 021219: OSN optical observations
  56. IPN triangulation of GRB021219
  57. GRB021219, optical observation by MASTER
  58. VLT spectra of GRB 021211 revisited
  59. GRB021219: a long GRB localized by INTEGRAL
  60. GRB021211: APO optical observations
  61. IPN detection of continued activity from SGR1806-20
  62. IPN triangulation of GRB021215 (large error box)
  63. IPN triangulation of GRB021214 (annulus)
  64. XRF 020903 : HST observations
  65. GRB 021211, optical observations
  66. GRB021211: Measurement of Early Time Afterglow
  67. IPN triangulation of GRB021211B (two large error boxes)
  68. GRB 021211: early break in light curve
  69. GRB021211: Optical observations in CrAO
  70. GRB 021211: Optical Observations
  71. GRB 021201, optical observations
  72. GRB021211: Optical observations
  73. GRB 021211 Milagro GeV/TeV Observations
  74. GRB021211 - Upper limits from recent and historical observations
  75. GRB021211, OT at 108 s
  76. GRB021211 (HETE2493), OT at 143 sec
  77. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  78. GRB 021125: Radio Observations
  79. IPN triangulation of GRB021206 (exceptionally bright; annulus only)
  80. IPN detection of renewed activity from SGR1806-20
  81. IPN triangulation of GRB021205 (large error box)
  82. GRB 021104, GRB 021112 and GRB 021113 - Milagro GeV/TeV Observations
  83. GRB 021201, Radio Observations
  84. IPN triangulation of GRB021201 (short/hard burst, small error box)
  85. IPN triangulation of GRB021115 (annulus)
  86. IPN triangulation of GRB021125B (two large error boxes)
  87. IPN triangulation of GRB021119 (large error box)
  88. IPN triangulation of GRB021125B (annulus)
  89. Improved IPN error box for GRB021125
  90. IPN triangulation of GRB021125 (INTEGRAL BURST)
  91. GRB021125 : A long GRB localized by INTEGRAL
  92. IPN detection of possible reactivation of SGR1900+14
  93. GRB021113, SPI ACS observation
  94. IPN triangulation of GRB021119 (annulus)
  95. GRB 021112: Afterglow or Variable Star?
  96. GRB 021112, Radio Observations
  97. GRB 021112: Variable Source in R-band search
  98. GRB021112: Optical Observations
  99. GRB021113: Kiso Observations
  100. IPN triangulation of GRB021113 (=H2449; annulus)

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