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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"

25053 results found.

  1. GRB030226: Optical decay index
  2. GRB 030226 Optical Spectra and R,I,z' Imaging
  3. GRB: Non-Referencing of GCN Circulars.
  4. IPN triangulation of GRB030217 (small error box)
  5. GRB 030131: marginal optical detection
  6. GRB 030204: Optical Observations
  7. GRB030204 field photometry
  8. GRB020819: Kiso R and I band observations
  9. GRB030131: Candidate Optical Afterglow
  10. IPN triangulation of GRB030204 (small error box)
  11. GRB 030131, optical observations
  12. GRB 030131: afterglow candidate
  13. GRB 030115, late-time optical observations
  14. GRB030131: corrected INTEGRAL position
  15. GRB 020819: Host galaxy at Radio Position
  16. IPN triangulation of GRB030131
  17. GRB 030131 optical observations
  18. GRB 030131 optical observations
  19. A long GRB detected by INTEGRAL
  20. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  21. GRB 030115, simultaneous observations by BOOTES-1
  22. GRB 030115: IR observations with IRSF/SIRIUS
  23. IPN triangulation of GRB030115C (large error box)
  24. GRB030115, afterglow candidate
  25. GRB 021211: R-band observations at late-time
  26. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  27. GRB 030115 : Possible IR counterpart
  28. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  29. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  30. GRB 030115: APO Optical Observations
  31. Information about where HETE will be pointing
  32. VLT spectroscopy of the probable host of GRB 021211
  33. IPN triangulation of GRB030101 (two large error boxes)
  34. GRB 021211: Probable Host and Underlying Supernova
  35. GRB 021112: Evidence for Another Dark Optical Afterglow
  36. GRB 021219: OSN optical observations
  37. GRB021219, optical observations
  38. GRB021219, optical observation by MASTER
  39. VLT spectra of GRB 021211 revisited
  40. GRB021219: a long GRB localized by INTEGRAL
  41. GRB021211: APO optical observations
  42. XRF 020903 : HST observations
  43. GRB 021201: Optical Observations
  44. GRB 021211: CTIO observations
  45. GRB021211, BVRI field photometry
  46. GRB021211: Optical observations in CrAO
  47. GRB 021211, optical observations
  48. GRB021211: Kiso Observations
  49. GRB 021201, optical observations
  50. GRB021211: Optical observations
  51. GRB 021201 (short/hard), NOT observations
  52. SUB-MM SEARCH FOR GRB 021211
  53. Chandra observation of the IPN error box of GRB021201 (short/hard)
  54. GRB 021211, R- and I-band observations
  55. GRB021211 - Upper limits from recent and historical observations
  56. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  57. IPN triangulation of GRB021206 (small error box)
  58. IPN triangulation of GRB021205 (large error box)
  59. GRB021201, BVRcIc field photometry
  60. GRB 021201: BOOTES simultaneous optical observations
  61. IPN triangulation of GRB021201 (short/hard burst, small error box)
  62. GRB021004, late time optical observations
  63. GRB021004 Chandra Observation
  64. IPN detection of continued SGR1900+14 activity
  65. Improved IPN error box for GRB021125
  66. IPN BURST POSITION
  67. IPN triangulation of GRB021125 (INTEGRAL BURST)
  68. GRB021125 : A long GRB localized by INTEGRAL
  69. IPN confirmation of the reactivation of SGR1900+14
  70. GRB021113, SPI ACS observation
  71. GRB 021112: Afterglow or Variable Star?
  72. GRB021113: optical observations at Bisei
  73. GRB 021113: Evidence for a Dark Optical Afterglow
  74. GRB021112, BVRI field photometry
  75. GRB 021112: Variable Source in R-band search
  76. GRB021112: Optical Observations
  77. IPN triangulation of GRB021113 (=H2449; annulus)
  78. GRB 021113: Optical observations
  79. GRB 021112: RAPTOR Observations
  80. GRB021113 (=H2449): A Long GRB Localized by HETE
  81. GRB021112 (=H2448): A Long GRB Localized by HETE
  82. GRB 021016: Optical Observations
  83. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  84. IPN triangulation of bursts from SGR1900+14, November 1-2, 2002
  85. SGR1900+14 activity, November 2-4, 2002
  86. GRB021104: optical observations
  87. Detection of activity from SGR 1900+14 with the RXTE/PCA
  88. IPN triangulation of GRB021027 (single large error box)
  89. IPN triangulation of GRB021027 (two large error boxes)
  90. GRB 021023: Curious K-band Source(s) Just Outside of IPN Localization
  91. GRB 021004: optical observations
  92. IPN triangulation of GRB021023 (small error boc)
  93. GRB 020813; likely host galaxy.
  94. IPN triangulation of GRB021020 (smaller error box)
  95. IPN triangulation of GRB021020
  96. GRB 021008, optical observations
  97. IPN triangulation of GRB021016 (small error box)
  98. IPN triangulation of GRB021014 (large error box)
  99. IPN triangulation of GRB021013 (single error box)
  100. GRB 021004: optical spectroscopy on Oct 11

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