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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"

32538 results found.

  1. GRB 030115: Further IR observations with IRSF/SIRIUS
  2. Publicizing GRB Discoveries - A Message from NASA HQ
  3. GRB 030115, simultaneous observations by BOOTES-1
  4. GRB 030115: IR observations with IRSF/SIRIUS
  5. GRB030115: R-band counterpart of IR candidate
  6. GRB030115, afterglow candidate
  7. GRB 021211: R-band observations at late-time
  8. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  9. IPN triangulation of GRB030115B (small error box)
  10. GRB 030115 : Possible IR counterpart
  11. GRB 030115: Radio Observations
  12. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  13. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  14. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  15. Distribution of INTEGRAL SPI-ACS triggers
  16. GRB030115: TAROT optical observations
  17. GRB 021211: VLT spectrum
  18. GRB 030115: APO Optical Observations
  19. GRB 030115, no optical candidate
  20. GRB 030115, optical observations
  21. GRB 030115, optical candidate
  22. IPN triangulation of GRB030109 (annulus)
  23. IPN triangulation of GRB030105 (large error box)
  24. IPN triangulation of GRB030102B (refined localization - portion of annulus)
  25. Coronas-F -Wind triangulation of GRB030102
  26. IPN triangulation of GRB030102 (annulus)
  27. VLT spectroscopy of the probable host of GRB 021211
  28. GRB021226
  29. GRB 021211: Probable Host and Underlying Supernova
  30. GRB 021226 registration by Helicon/Coronas-F
  31. GRB 021112: Evidence for Another Dark Optical Afterglow
  32. GRB 021219: OSN optical observations
  33. GRB021219: Radio Observations
  34. GRB021219, optical observations
  35. IPN triangulation of GRB021219 - CORRECTION
  36. IPN triangulation of GRB021219
  37. GRB021219, optical observation by MASTER
  38. GRB021219: Correction to GCN 1766
  39. VLT spectra of GRB 021211 revisited
  40. GRB021219: a long GRB localized by INTEGRAL
  41. GRB021211: APO optical observations
  42. IPN detection of continued activity from SGR1806-20
  43. XRF 020903 : HST observations
  44. GRB 021201: Optical Observations
  45. GRB 021211, optical observations
  46. GRB 021211: CTIO observations
  47. GRB021211: Measurement of Early Time Afterglow
  48. VLT spectrum of GRB 021211
  49. GRB 021211: early break in light curve
  50. GRB021211, BVRI field photometry
  51. GRB021211: Optical observations in CrAO
  52. GRB 021211, IR observations
  53. GRB 021211, optical observations
  54. GRB 021211: Optical Observations
  55. GRB021211: Kiso Observations
  56. GRB 021201, optical observations
  57. GRB 021211: Radio Observations
  58. GRB021211: Optical observations
  59. GRB 021201 (short/hard), NOT observations
  60. SUB-MM SEARCH FOR GRB 021211
  61. Chandra observation of the IPN error box of GRB021201 (short/hard)
  62. GRB 021211, R- and I-band observations
  63. GRB021211 - Upper limits from recent and historical observations
  64. GRB021211, OT at 108 s
  65. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  66. HETE 2493: Optical observations
  67. GRB 021125: Radio Observations
  68. IPN triangulation of GRB021206 (small error box)
  69. GRB 021104, GRB 021112 and GRB 021113 - Milagro GeV/TeV Observations
  70. GRB021201, BVRcIc field photometry
  71. GRB 021201, Radio Observations
  72. GRB 021201: Optical Observations
  73. GRB 021201: BOOTES simultaneous optical observations
  74. GRB021004, late time optical observations
  75. GRB021004 Chandra Observation
  76. GRB021125 refined position
  77. IPN triangulation of GRB021125B (two large error boxes)
  78. IPN triangulation of GRB021119 (large error box)
  79. Improved IPN error box for GRB021125
  80. IPN BURST POSITION
  81. IPN confirmation of the reactivation of SGR1900+14
  82. GRB021113, SPI ACS observation
  83. GRB 021112: Afterglow or Variable Star?
  84. GRB021113: optical observations at Bisei
  85. GRB 021113: Evidence for a Dark Optical Afterglow
  86. GRB 021112: Variable Source in R-band search
  87. GRB021112: Optical Observations
  88. IPN triangulation of GRB021109 (portion of annulus)
  89. IPN triangulation of GRB021113 (=H2449; annulus)
  90. IPN triangulation of GRB021108 (CORRECTION; TWO LARGE ERROR BOXES)
  91. GRB 021113: Optical Observations
  92. GRB 021113: Optical Observations
  93. GRB021113 (=H2449): A Long GRB Localized by HETE
  94. GRB 021112: Optical Observations
  95. GRB 021112: R-band search
  96. IPN triangulation of GRB021108 (large error box)
  97. GRB021112 (=H2448): A Long GRB Localized by HETE
  98. GRB 021016: Optical Observations
  99. GRB021004: Near infrared spectroscopy
  100. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE

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