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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"
  1. GRB030131: refined position
  2. GRB 030131 optical observations
  3. A long GRB detected by INTEGRAL
  4. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  5. Type Ic SN2003L (SN/GRB?) Radio Observations
  6. IPN triangulation of GRB030127 (annulus)
  7. GRB030115 submm upper limit
  8. IPN triangulation of GRB030119 (two large error boxes)
  9. GRB 030115: Further IR observations with IRSF/SIRIUS
  10. IPN triangulation of GRB030117 (two large error boxes)
  11. Publicizing GRB Discoveries - A Message from NASA HQ
  12. GRB 030115: Radio detection of IR candidate
  13. GRB 030115, simultaneous observations by BOOTES-1
  14. GRB 030115: IR observations with IRSF/SIRIUS
  15. IPN triangulation of GRB030115C (large error box)
  16. GRB030115: R-band counterpart of IR candidate
  17. GRB030115, afterglow candidate
  18. GRB 021211: R-band observations at late-time
  19. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  20. IPN triangulation of GRB030115B (small error box)
  21. GRB 030115 : Possible IR counterpart
  22. GRB 030115: Radio Observations
  23. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  24. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  25. IPN triangulation of GRB030115B (annulus)
  26. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  27. Distribution of INTEGRAL SPI-ACS triggers
  28. GRB030115: R-band observations at Asiago
  29. GRB030115: TAROT optical observations
  30. GRB 021211: VLT spectrum
  31. GRB 030115: APO Optical Observations
  32. GRB 030115, no optical candidate
  33. GRB 030115, optical observations
  34. GRB 030115, optical candidate
  35. Possible GRB030113 seen by SPI ACS
  36. Probable GRB030112B seen by SPI ACS
  37. Probable GRB030112 seen by SPI ACS
  38. Information about where HETE will be pointing
  39. Possible GRB030111 seen by SPI ACS
  40. Possible GRB030110b seen by SPI ACS
  41. Possible GRB 030110 seen by SPI ACS
  42. IPN triangulation of GRB030109 (annulus)
  43. IPN triangulation of GRB030105 (large error box)
  44. IPN triangulation of GRB030102B (refined localization - portion of annulus)
  45. Possible GRB 20030109 seen by SPI ACS
  46. IPN triangulation of GRB030102A - correction to peak flux
  47. IPN triangulation of GRB030102B (portion of annulus)
  48. IPN triangulation of GRB030102A (large error box)
  49. Coronas-F -Wind triangulation of GRB030102
  50. Possible GRB20030107 seen by SPI-ACS
  51. Possible GRB 20030105 seen by SPI ACS
  52. IPN triangulation of GRB030102 (annulus)
  53. GRB on 20030102 seen by SPI-ACS
  54. VLT spectroscopy of the probable host of GRB 021211
  55. GRB on 20030101 seen by SPI-ACS
  56. IPN triangulation of GRB030101 (two large error boxes)
  57. GRB021226
  58. GRB 021211: Probable Host and Underlying Supernova
  59. GRB 021226 registration by Helicon/Coronas-F
  60. Probable GRB in INTEGRAL SPI-ACS
  61. IPN triangulation of GRB021223 (two large error boxes)
  62. GRB021211, radio observations
  63. GRB 021112: Evidence for Another Dark Optical Afterglow
  64. GRB 021219: OSN optical observations
  65. GRB021219: Radio Observations
  66. GRB021219, optical observations
  67. IPN triangulation of GRB021219 - CORRECTION
  68. IPN triangulation of GRB021219
  69. GRB021219, optical observation by MASTER
  70. GRB021219: Correction to GCN 1766
  71. GRB021219 refined position with INTEGRAL
  72. VLT spectra of GRB 021211 revisited
  73. GRB021219: a long GRB localized by INTEGRAL
  74. GRB021211: APO optical observations
  75. IPN detection of continued activity from SGR1806-20
  76. IPN triangulation of GRB021215 (large error box)
  77. IPN triangulation of GRB021214 (annulus)
  78. XRF 020903 : HST observations
  79. GRB 021201: Optical Observations
  80. GRB 021211, optical observations
  81. GRB 021211: CTIO observations
  82. GRB021211: Measurement of Early Time Afterglow
  83. VLT spectrum of GRB 021211
  84. IPN triangulation of GRB021211B (two large error boxes)
  85. GRB 021211: early break in light curve
  86. GRB021211, BVRI field photometry
  87. GRB021211: Optical observations in CrAO
  88. GRB 021211, IR observations
  89. GRB 021211, optical observations
  90. GRB 021211: Optical Observations
  91. GRB021211: Kiso Observations
  92. GRB021204: Kiso Observations
  93. GRB 021201, optical observations
  94. GRB 021211: Radio Observations
  95. GRB021211: Optical observations
  96. GRB 021201 (short/hard), NOT observations
  97. SUB-MM SEARCH FOR GRB 021211
  98. Chandra observation of the IPN error box of GRB021201 (short/hard)
  99. GRB 021211 Milagro GeV/TeV Observations
  100. GRB 021211, R- and I-band observations

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