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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"

38363 results found.

  1. GRB 020819: Host galaxy at Radio Position
  2. IPN triangulation of GRB030131 - CORRECTION
  3. GRB 020819: afterglow candidate
  4. IPN triangulation of GRB030131
  5. GRB030131: Optical limit
  6. GRB 030131 optical observations
  7. A long GRB detected by INTEGRAL
  8. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  9. Type Ic SN2003L (SN/GRB?) Radio Observations
  10. IPN triangulation of GRB030127 (annulus)
  11. GRB030115 submm upper limit
  12. IPN triangulation of GRB030119 (two large error boxes)
  13. GRB 030115: Further IR observations with IRSF/SIRIUS
  14. IPN triangulation of GRB030117 (two large error boxes)
  15. Publicizing GRB Discoveries - A Message from NASA HQ
  16. GRB 030115: Radio detection of IR candidate
  17. GRB 030115, simultaneous observations by BOOTES-1
  18. GRB 030115: IR observations with IRSF/SIRIUS
  19. IPN triangulation of GRB030115C (large error box)
  20. GRB030115: R-band counterpart of IR candidate
  21. GRB030115, afterglow candidate
  22. GRB 021211: R-band observations at late-time
  23. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  24. IPN triangulation of GRB030115B (small error box)
  25. GRB 030115 : Possible IR counterpart
  26. GRB 030115: Radio Observations
  27. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  28. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  29. IPN triangulation of GRB030115B (annulus)
  30. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  31. Distribution of INTEGRAL SPI-ACS triggers
  32. GRB030115: R-band observations at Asiago
  33. GRB 021211: VLT spectrum
  34. GRB 030115: APO Optical Observations
  35. GRB 030115, no optical candidate
  36. GRB 030115, optical observations
  37. GRB 030115, optical candidate
  38. Possible GRB030113 seen by SPI ACS
  39. Probable GRB030112B seen by SPI ACS
  40. Probable GRB030112 seen by SPI ACS
  41. Information about where HETE will be pointing
  42. Possible GRB030111 seen by SPI ACS
  43. Possible GRB030110b seen by SPI ACS
  44. Possible GRB 030110 seen by SPI ACS
  45. IPN triangulation of GRB030109 (annulus)
  46. IPN triangulation of GRB030105 (large error box)
  47. IPN triangulation of GRB030102B (refined localization - portion of annulus)
  48. Possible GRB 20030109 seen by SPI ACS
  49. IPN triangulation of GRB030102B (portion of annulus)
  50. IPN triangulation of GRB030102A (large error box)
  51. Coronas-F -Wind triangulation of GRB030102
  52. Possible GRB20030107 seen by SPI-ACS
  53. Possible GRB 20030105 seen by SPI ACS
  54. IPN triangulation of GRB030102 (annulus)
  55. GRB on 20030102 seen by SPI-ACS
  56. VLT spectroscopy of the probable host of GRB 021211
  57. GRB on 20030101 seen by SPI-ACS
  58. IPN triangulation of GRB030101 (two large error boxes)
  59. GRB021226
  60. GRB 021211: Probable Host and Underlying Supernova
  61. GRB 021226 registration by Helicon/Coronas-F
  62. Probable GRB in INTEGRAL SPI-ACS
  63. IPN triangulation of GRB021223 (two large error boxes)
  64. GRB021211, radio observations
  65. GRB 021112: Evidence for Another Dark Optical Afterglow
  66. GRB 021219: OSN optical observations
  67. GRB021219: Radio Observations
  68. IPN triangulation of GRB021219 - CORRECTION
  69. IPN triangulation of GRB021219
  70. GRB021219: a long GRB localized by INTEGRAL
  71. GRB021211: APO optical observations
  72. IPN detection of continued activity from SGR1806-20
  73. IPN triangulation of GRB021215 (large error box)
  74. IPN triangulation of GRB021214 (annulus)
  75. XRF 020903 : HST observations
  76. GRB 021201: Optical Observations
  77. GRB 021211, optical observations
  78. GRB 021211: CTIO observations
  79. GRB021211: Measurement of Early Time Afterglow
  80. IPN triangulation of GRB021211B (two large error boxes)
  81. GRB021211, BVRI field photometry
  82. GRB021211: Optical observations in CrAO
  83. GRB 021211, IR observations
  84. GRB 021211, optical observations
  85. GRB 021211: Optical Observations
  86. GRB021211: Kiso Observations
  87. GRB021204: Kiso Observations
  88. GRB 021201, optical observations
  89. GRB 021211: Radio Observations
  90. GRB021211: Optical observations
  91. GRB 021201 (short/hard), NOT observations
  92. SUB-MM SEARCH FOR GRB 021211
  93. Chandra observation of the IPN error box of GRB021201 (short/hard)
  94. GRB 021211 Milagro GeV/TeV Observations
  95. GRB 021211, R- and I-band observations
  96. GRB021211 - Upper limits from recent and historical observations
  97. GRB021211 (HETE2493), OT at 143 sec
  98. GRB 021204: I-band Observations
  99. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  100. HETE 2493: Optical candidate

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