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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. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  2. Type Ic SN2003L (SN/GRB?) Radio Observations
  3. IPN triangulation of GRB030127 (annulus)
  4. GRB030115 submm upper limit
  5. IPN triangulation of GRB030119 (two large error boxes)
  6. GRB 030115: Further IR observations with IRSF/SIRIUS
  7. IPN triangulation of GRB030117 (two large error boxes)
  8. Publicizing GRB Discoveries - A Message from NASA HQ
  9. GRB 030115: Radio detection of IR candidate
  10. GRB 030115, simultaneous observations by BOOTES-1
  11. GRB 030115: IR observations with IRSF/SIRIUS
  12. IPN triangulation of GRB030115C (large error box)
  13. GRB030115: R-band counterpart of IR candidate
  14. GRB030115, afterglow candidate
  15. GRB 021211: R-band observations at late-time
  16. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  17. IPN triangulation of GRB030115B (small error box)
  18. GRB 030115 : Possible IR counterpart
  19. GRB 030115: Radio Observations
  20. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  21. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  22. IPN triangulation of GRB030115B (annulus)
  23. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  24. Distribution of INTEGRAL SPI-ACS triggers
  25. GRB030115: R-band observations at Asiago
  26. GRB030115: TAROT optical observations
  27. GRB 021211: VLT spectrum
  28. GRB 030115: APO Optical Observations
  29. GRB 030115, no optical candidate
  30. GRB 030115, optical observations
  31. GRB 030115, optical candidate
  32. Possible GRB030113 seen by SPI ACS
  33. Probable GRB030112B seen by SPI ACS
  34. Probable GRB030112 seen by SPI ACS
  35. Information about where HETE will be pointing
  36. Possible GRB030111 seen by SPI ACS
  37. Possible GRB030110b seen by SPI ACS
  38. Possible GRB 030110 seen by SPI ACS
  39. IPN triangulation of GRB030109 (annulus)
  40. IPN triangulation of GRB030105 (large error box)
  41. IPN triangulation of GRB030102B (refined localization - portion of annulus)
  42. Possible GRB 20030109 seen by SPI ACS
  43. IPN triangulation of GRB030102A - correction to peak flux
  44. IPN triangulation of GRB030102B (portion of annulus)
  45. IPN triangulation of GRB030102A (large error box)
  46. Coronas-F -Wind triangulation of GRB030102
  47. Possible GRB20030107 seen by SPI-ACS
  48. Possible GRB 20030105 seen by SPI ACS
  49. IPN triangulation of GRB030102 (annulus)
  50. GRB on 20030102 seen by SPI-ACS
  51. VLT spectroscopy of the probable host of GRB 021211
  52. GRB on 20030101 seen by SPI-ACS
  53. IPN triangulation of GRB030101 (two large error boxes)
  54. GRB021226
  55. GRB 021211: Probable Host and Underlying Supernova
  56. GRB 021226 registration by Helicon/Coronas-F
  57. Probable GRB in INTEGRAL SPI-ACS
  58. IPN triangulation of GRB021223 (two large error boxes)
  59. GRB021211, radio observations
  60. GRB 021112: Evidence for Another Dark Optical Afterglow
  61. GRB 021219: OSN optical observations
  62. GRB021219: Radio Observations
  63. GRB021219, optical observations
  64. IPN triangulation of GRB021219 - CORRECTION
  65. IPN triangulation of GRB021219
  66. GRB021219, optical observation by MASTER
  67. GRB021219: Correction to GCN 1766
  68. GRB021219 refined position with INTEGRAL
  69. VLT spectra of GRB 021211 revisited
  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. VLT spectrum of GRB 021211
  81. IPN triangulation of GRB021211B (two large error boxes)
  82. GRB 021211: early break in light curve
  83. GRB021211, BVRI field photometry
  84. GRB021211: Optical observations in CrAO
  85. GRB 021211, IR observations
  86. GRB 021211, optical observations
  87. GRB 021211: Optical Observations
  88. GRB021211: Kiso Observations
  89. GRB021204: Kiso Observations
  90. GRB 021201, optical observations
  91. GRB 021211: Radio Observations
  92. GRB021211: Optical observations
  93. GRB 021201 (short/hard), NOT observations
  94. SUB-MM SEARCH FOR GRB 021211
  95. Chandra observation of the IPN error box of GRB021201 (short/hard)
  96. GRB 021211 Milagro GeV/TeV Observations
  97. GRB 021211, R- and I-band observations
  98. GRB021211 - Upper limits from recent and historical observations
  99. GRB021211, OT at 108 s
  100. GRB021211 (HETE2493), OT at 143 sec

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