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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"

15242 results found.

  1. GRB 030226: Optical observations
  2. GRB 030227, possible optical counterpart of XMM-Newton source
  3. GRB030227 - faint tentative OT candidate
  4. XMM-Newton observation of GRB030227
  5. GRB 030227: Kyoto optical observation
  6. GRB 030226, optical light curve
  7. GRB 030226 spectroscopy
  8. GRB030227: refined INTEGRAL position
  9. GRB 030226 : Predicted light curve
  10. GRB 030226: Confirmed decay index
  11. GRB030226: ESI spectroscopy
  12. GRB030226 (=U10893): A Long GRB Localized by the HETE WXM and SXC
  13. GRB030226: optical observations and refined redshift
  14. GRB 030226: Optical afterglow
  15. GRB: Non-Referencing of GCN Circulars.
  16. GRB020819: Kiso R and I band observations
  17. GRB 030131, optical observations
  18. GRB 030131: afterglow candidate
  19. GRB 030115, late-time optical observations
  20. GRB030131: corrected INTEGRAL position
  21. GRB030131: Kiso Observations
  22. GRB 020819: Host galaxy at Radio Position
  23. GRB030131: refined position
  24. Publicizing GRB Discoveries - A Message from NASA HQ
  25. GRB030115: R-band counterpart of IR candidate
  26. GRB 021211: R-band observations at late-time
  27. GRB030115: Optical Observations, Swiss Telescope at La Silla (ESO, Chile)
  28. GRB030115 (=H2533): A Long GRB Localized by the HETE WXM and SXC
  29. ANNOUNCEMENT ON INTEGRAL GRB ALERTS
  30. GRB030115: TAROT optical observations
  31. GRB 030115: APO Optical Observations
  32. GRB 030115, no optical candidate
  33. VLT spectroscopy of the probable host of GRB 021211
  34. GRB 021211: Probable Host and Underlying Supernova
  35. GRB021219: Correction to GCN 1766
  36. VLT spectra of GRB 021211 revisited
  37. GRB021219: a long GRB localized by INTEGRAL
  38. GRB021211: APO optical observations
  39. GRB021211: Measurement of Early Time Afterglow
  40. GRB021211: Optical observations in CrAO
  41. GRB 021211: Optical Observations
  42. GRB021211: Optical observations
  43. GRB 021201 (short/hard), NOT observations
  44. GRB 021211 Milagro GeV/TeV Observations
  45. GRB021211, OT at 108 s
  46. GRB021211 (HETE2493), OT at 143 sec
  47. GRB021211 (=H2493): A Bright, Long GRB Localized by HETE-2 in Near-Real Time
  48. HETE 2493: Optical observations
  49. IPN triangulation of GRB021206 (exceptionally bright; annulus only)
  50. IPN detection of renewed activity from SGR1806-20
  51. GRB 021104, GRB 021112 and GRB 021113 - Milagro GeV/TeV Observations
  52. GRB021125 : A long GRB localized by INTEGRAL
  53. GRB021113, SPI ACS observation
  54. GRB 021112, Radio Observations
  55. GRB 021112: Variable Source in R-band search
  56. GRB021112: Optical Observations
  57. IPN triangulation of GRB021108 (CORRECTION; TWO LARGE ERROR BOXES)
  58. GRB021113 (=H2449): A Long GRB Localized by HETE
  59. GRB021112 (=H2448): A Long GRB Localized by HETE
  60. GRB021104(=H2434): A Long, X-Ray-Rich GRB Localized by HETE
  61. IPN triangulation of bursts from SGR1900+14, November 1-2, 2002
  62. SGR1900+14 activity, November 2-4, 2002
  63. Spectropolarimetry of GRB021004
  64. GRB021104: optical observations
  65. GRB021104: Candidate present in DSS
  66. Detection of activity from SGR 1900+14 with the RXTE/PCA
  67. GRB 021023: Curious K-band Source(s) Just Outside of IPN Localization
  68. GRB021004: Optical Observations
  69. GRB 020813; likely host galaxy.
  70. GRB021021(=XRF 021021): An X-ray Flash Localized by HETE
  71. GRB 021004: VRI observations at TNG: possible break
  72. GRB 021008, optical observations
  73. GRB021016(=H2397): A Long GRB Localized by HETE
  74. GRB021004: Optical Observations
  75. GRB 021004: optical spectroscopy on Oct 11
  76. GRB021004: High-resolution optical spectroscopy
  77. GRB021004: Optical Observations
  78. GRB021004 Chandra HETG Observations
  79. GRB 021004: Host Galaxy Star Formation Rate
  80. GRB 021004: WC wind?
  81. GRB 021004: Optical observations, AUDE network
  82. GRB 021004 - Unusual Radio-to-Submm Spectrum
  83. GRB 021004: optical spectroscopy
  84. XRF 020903 spectrum
  85. GRB 021004: HST/STIS spectroscopic observations
  86. GRB021004: optical observations and predicted break time
  87. GRB 021004 redshift
  88. GRB 021004 continued IR fading
  89. HETE fluences for GRB021004
  90. GRB021004: Update Bisei photometric data
  91. GRB 021004: Optical Decay
  92. GRB021004, astrometric position
  93. GRB 021004: Optical observations at RIKEN
  94. GRB 021004: Optical Observations
  95. GRB021004, BVRcIc field photometry
  96. GRB 021004: Optical observations
  97. GRB021004: Optical Spectroscopy
  98. GRB 021004, SPM optical observations
  99. GRB 021004: radio observations
  100. GRB021004: optical observations at Nyrola

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