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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"

28057 results found.

  1. GRB030226: ESI spectroscopy
  2. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  3. GRB 030226 simultaneous optical observations
  4. GRB 030226, optical observations
  5. GRB030226: Optical decay index
  6. GRB 030226 Optical Spectra and R,I,z' Imaging
  7. GRB: Non-Referencing of GCN Circulars.
  8. IPN triangulation of GRB030217 (small error box)
  9. GRB 030131: marginal optical detection
  10. GRB 030204: Optical Observations
  11. GRB030204 field photometry
  12. GRB020819: Kiso R and I band observations
  13. GRB030131: Candidate Optical Afterglow
  14. IPN triangulation of GRB030204 (small error box)
  15. GRB 030131, optical observations
  16. GRB 030131: afterglow candidate
  17. GRB 030115, late-time optical observations
  18. GRB030131: corrected INTEGRAL position
  19. GRB 020819: Host galaxy at Radio Position
  20. IPN triangulation of GRB030131
  21. GRB 030131 optical observations
  22. GRB 030131 optical observations
  23. A long GRB detected by INTEGRAL
  24. GRB030115: 1.2 mm upper limits with MAMBO @ IRAM 30m
  25. GRB 030115, simultaneous observations by BOOTES-1
  26. GRB 030115: IR observations with IRSF/SIRIUS
  27. IPN triangulation of GRB030115C (large error box)
  28. GRB030115, afterglow candidate
  29. GRB 021211: R-band observations at late-time
  30. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  31. GRB 030115 : Possible IR counterpart
  32. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  33. Distribution of INTEGRAL SPI-ACS triggers for GRB bursts
  34. GRB 030115: APO Optical Observations
  35. Information about where HETE will be pointing
  36. VLT spectroscopy of the probable host of GRB 021211
  37. IPN triangulation of GRB030101 (two large error boxes)
  38. GRB 021211: Probable Host and Underlying Supernova
  39. GRB 021112: Evidence for Another Dark Optical Afterglow
  40. GRB 021219: OSN optical observations
  41. GRB021219, optical observations
  42. GRB021219, optical observation by MASTER
  43. VLT spectra of GRB 021211 revisited
  44. GRB021219: a long GRB localized by INTEGRAL
  45. GRB021211: APO optical observations
  46. XRF 020903 : HST observations
  47. GRB 021201: Optical Observations
  48. GRB 021211: CTIO observations
  49. GRB021211, BVRI field photometry
  50. GRB021211: Optical observations in CrAO
  51. GRB 021211, optical observations
  52. GRB021211: Kiso Observations
  53. GRB 021201, optical observations
  54. GRB021211: Optical observations
  55. GRB 021201 (short/hard), NOT observations
  56. SUB-MM SEARCH FOR GRB 021211
  57. Chandra observation of the IPN error box of GRB021201 (short/hard)
  58. GRB 021211, R- and I-band observations
  59. GRB021211 - Upper limits from recent and historical observations
  60. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  61. IPN triangulation of GRB021206 (small error box)
  62. IPN triangulation of GRB021205 (large error box)
  63. GRB021201, BVRcIc field photometry
  64. GRB 021201: BOOTES simultaneous optical observations
  65. IPN triangulation of GRB021201 (short/hard burst, small error box)
  66. GRB021004, late time optical observations
  67. GRB021004 Chandra Observation
  68. IPN detection of continued SGR1900+14 activity
  69. Improved IPN error box for GRB021125
  70. IPN BURST POSITION
  71. IPN triangulation of GRB021125 (INTEGRAL BURST)
  72. GRB021125 : A long GRB localized by INTEGRAL
  73. IPN confirmation of the reactivation of SGR1900+14
  74. GRB021113, SPI ACS observation
  75. GRB 021112: Afterglow or Variable Star?
  76. GRB021113: optical observations at Bisei
  77. GRB 021113: Evidence for a Dark Optical Afterglow
  78. GRB021112, BVRI field photometry
  79. GRB 021112: Variable Source in R-band search
  80. GRB021112: Optical Observations
  81. IPN triangulation of GRB021113 (=H2449; annulus)
  82. GRB 021113: Optical observations
  83. GRB 021112: RAPTOR Observations
  84. GRB021113 (=H2449): A Long GRB Localized by HETE
  85. GRB021112 (=H2448): A Long GRB Localized by HETE
  86. GRB 021016: Optical Observations
  87. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  88. IPN triangulation of bursts from SGR1900+14, November 1-2, 2002
  89. SGR1900+14 activity, November 2-4, 2002
  90. GRB021104: optical observations
  91. Detection of activity from SGR 1900+14 with the RXTE/PCA
  92. IPN triangulation of GRB021027 (single large error box)
  93. IPN triangulation of GRB021027 (two large error boxes)
  94. GRB 021023: Curious K-band Source(s) Just Outside of IPN Localization
  95. GRB 021004: optical observations
  96. IPN triangulation of GRB021023 (small error boc)
  97. GRB 020813; likely host galaxy.
  98. IPN triangulation of GRB021020 (smaller error box)
  99. IPN triangulation of GRB021020
  100. GRB 021008, optical observations

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