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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. RHESSI Spectrum of GRB070125
  2. IPN-BAT localization of GRB070125 (very long duration, intense)
  3. Konus-Wind observation of short hard GRB 070124
  4. IPN localization of GRB070124 (short duration, hard spectrum)
  5. GRB 070110: optical break
  6. Swift-BAT trigger 257213 is a Galactic Center transient
  7. GRB 070110: Continued Detection and Request for Ground Followup
  8. GRB 050904: Second Epoch of HST/NICMOS Observations
  9. GRB 070110: Ep,i - Eiso correlation
  10. GRB 070107: Suzaku WAM observation of the prompt emission
  11. GRB 070110: VLT R-band photometry
  12. GRB 070110 declared a "Burst of Interest" by Swift team
  13. Further Retractions of previous Swift-BAT triggers
  14. Swift-BAT Trigger 255685 is not a GRB
  15. Trigger 255685: Swift detection of a possible burst
  16. GRB 070110: VLT absorption redshift
  17. GRB 070110: UVOT Observations of a Candidate Afterglow
  18. GRB070110: Swift XRT Team refined analysis
  19. GRB 070110, Swift-BAT refined analysis
  20. GRB070107 Swift/UVOT Observations of a Fading Optical Afterglow
  21. GRB 070110: Swift detection of a burst with a possible optical afterglow
  22. IBAS Alert n. 4047: Not a GRB
  23. GRB070107: Swift/XRT refined analysis
  24. GRB 070107: Possible UVOT Afterglow
  25. GRB 070107, Swift-BAT refined analysis
  26. GRB 070107: Swift/XRT position
  27. GRB 070107: Swift detection of a burst
  28. VLA observation of GRB 061222B
  29. VLA detection of GRB 061222A
  30. GRB070103: APO SPIcam i' and z' limits
  31. GRB 061201: Nearby Galaxy Cluster Abell 995 is at z=0.0865
  32. GRB070103: KPNO 4m+FLAMINGOS J limit
  33. GRB 070103: Swift/UVOT Upper limits
  34. GRB070103: Swift XRT refined analysis
  35. GRB 070103, Swift-BAT refined analysis
  36. GRB 070103: NOT observations
  37. GRB 070103: TAROT Calern observatory optical observations
  38. GRB 070103: Swift detection of a burst
  39. Retractions of previous Swift-BAT triggers
  40. GRB061222a: optical observations
  41. erratum : SDSS Pre-burst Observations of GRB061126
  42. Konus-Wind observation of GRB 061222A
  43. GRB 061210: Swift/XRT Astrometry Correction
  44. GRB 050826: MDM Redshift
  45. GRB 061222B: TAROT La Silla observatory early optical observations
  46. GRB 061218: TAROT La Silla observatory early optical observations
  47. GRB 061222A: MITSuME Akeno optical upper limits
  48. GRB 061222A: Confirmation of Gemini Afterglow Candidate
  49. GRB 061222B: MITSuME Akeno optical upper limits
  50. GRB 061222A: Xinglong Optical Limit
  51. GRB 061222A: Gemini Afterglow Candidate
  52. GRB 061222B, Swift-BAT refined analysis
  53. GRB061222A Swift/UVOT: Upper Limits
  54. GRB 061222B: Swift/UVOT Upper limits
  55. GRB 061222B: Observation with the KANATA 1.5m telescope
  56. GRB061222B: Swift-XRT Refined Analysis
  57. GRB 061222A: Observation with the KANATA 1.5m telescope
  58. GRB 061222B: BOOTES-IR optical observations
  59. GRB 061222B: SARA upper limit
  60. GRB 061222A: Swift-XRT refined analysis
  61. GRB 061217: Magellan host galaxy redshift
  62. GRB 061222A, Swift-BAT refined analysis
  63. GRB 061222B: REM NIR/optical observations
  64. GRB 061222b: Refined redshift
  65. GRB 061222b, SMARTS optical/IR afterglow observations
  66. GRB 061222B: TAROT La Silla observatory afterglow observation
  67. GRB 061222B: TAROT La Silla observatory optical observations
  68. GRB 061222b: Magellan redshift
  69. GRB 061222B: Swift detection of a burst
  70. GRB 061222b: optical afterglow
  71. GRB 061222A: Prompt ROTSE-III Optical Limits
  72. GRB 061222: Swift detection of a burst
  73. GRB 061217: Astrometry-Corrected XRT Position
  74. GRB 061201: Magellan redshift of nearby galaxy
  75. GRB 061217: Confirmation of host candidate
  76. GRB 061217: Object ib GCN 5948 is a star
  77. GRB 061217: Extended object in the revised XRT error circle
  78. GRB 061217, Candidate host galaxy
  79. GRB 061217 - Swift/XRT position correction
  80. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  81. GRB 061201: Correction to GCN 5944
  82. GRB 061201: Magellan Redshift of nearby Abell cluster
  83. GRB 061218: TAROT La Silla observatory optical observations
  84. GRB 061217: TAROT Calern observatory optical observations
  85. GRB 061218: TORTOREM optical upper limits
  86. GRB 061218, Swift-BAT refined analysis
  87. GRB061217: VLT NIR observations
  88. GRB 061218, SMARTS optical/IR observations
  89. GRB 061218: REM prompt observations
  90. Swift triggers (#251863) on a possible burst
  91. GRB 061217, SMARTS optical observations
  92. GRB061217: Swift/UVOT refined analysis.
  93. GRB 061217: optical observations at Calar Alto
  94. GRB061217 - Swift/XRT refined analysis
  95. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  96. GRB 061217, Swift-BAT refined analysis
  97. GRB 061217: Magellan Observations
  98. GRB 061217: REM prompt observations
  99. GRB 061217: ROTSE-III Optical Limits
  100. GRB 061217: Swift detection of a short hard burst

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