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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. GRB 070125: UVOT Observations of a Fading Optical Afterglow
  2. GRB 070125: Xinglong TNT optical observations
  3. GRB 070125: Continued P60 Observations
  4. GRB 070125: pseudo-z~1.5 from spectral parameters of the prompt emission
  5. GRB 070125: Keck/LRIS Spectroscopy -- Evidence for a very low redshift
  6. GRB 070125: Lick 3m Spectroscopy
  7. GRB070125: Swift-XRT Refined Analysis
  8. GRB 070125: SARA detection in R
  9. GRB 070125: P60 Optical Afterglow Candidate
  10. GRB 070126?: Swift detection of a possible burst
  11. GRB070125 redshift request
  12. RHESSI Spectrum of GRB070125
  13. IPN-BAT localization of GRB070125 (very long duration, intense)
  14. Konus-Wind observation of short hard GRB 070124
  15. IPN localization of GRB070124 (short duration, hard spectrum)
  16. GRB 070110: optical break
  17. Swift-BAT trigger 257213 is a Galactic Center transient
  18. GRB 070110: Continued Detection and Request for Ground Followup
  19. GRB 050904: Second Epoch of HST/NICMOS Observations
  20. GRB 070110: Ep,i - Eiso correlation
  21. GRB 070107: Suzaku WAM observation of the prompt emission
  22. GRB 070110: VLT R-band photometry
  23. GRB 070110 declared a "Burst of Interest" by Swift team
  24. Further Retractions of previous Swift-BAT triggers
  25. Swift-BAT Trigger 255685 is not a GRB
  26. Trigger 255685: Swift detection of a possible burst
  27. GRB 070110: VLT absorption redshift
  28. GRB 070110: UVOT Observations of a Candidate Afterglow
  29. GRB070110: Swift XRT Team refined analysis
  30. GRB 070110, Swift-BAT refined analysis
  31. GRB070107 Swift/UVOT Observations of a Fading Optical Afterglow
  32. GRB 070110: Swift detection of a burst with a possible optical afterglow
  33. IBAS Alert n. 4047: Not a GRB
  34. GRB070107: Swift/XRT refined analysis
  35. GRB 070107: Possible UVOT Afterglow
  36. GRB 070107, Swift-BAT refined analysis
  37. GRB 070107: Swift/XRT position
  38. GRB 070107: Swift detection of a burst
  39. VLA observation of GRB 061222B
  40. VLA detection of GRB 061222A
  41. GRB070103: APO SPIcam i' and z' limits
  42. GRB 061201: Nearby Galaxy Cluster Abell 995 is at z=0.0865
  43. GRB070103: KPNO 4m+FLAMINGOS J limit
  44. GRB 070103: Swift/UVOT Upper limits
  45. GRB070103: Swift XRT refined analysis
  46. GRB 070103, Swift-BAT refined analysis
  47. GRB 070103: NOT observations
  48. GRB 070103: TAROT Calern observatory optical observations
  49. GRB 070103: Swift detection of a burst
  50. Retractions of previous Swift-BAT triggers
  51. GRB061222a: optical observations
  52. erratum : SDSS Pre-burst Observations of GRB061126
  53. Konus-Wind observation of GRB 061222A
  54. GRB 061210: Swift/XRT Astrometry Correction
  55. GRB 050826: MDM Redshift
  56. GRB 061222B: TAROT La Silla observatory early optical observations
  57. GRB 061218: TAROT La Silla observatory early optical observations
  58. GRB 061222A: MITSuME Akeno optical upper limits
  59. GRB 061222A: Confirmation of Gemini Afterglow Candidate
  60. GRB 061222B: MITSuME Akeno optical upper limits
  61. GRB 061222A: Xinglong Optical Limit
  62. GRB 061222A: Gemini Afterglow Candidate
  63. GRB 061222B, Swift-BAT refined analysis
  64. GRB061222A Swift/UVOT: Upper Limits
  65. GRB 061222B: Swift/UVOT Upper limits
  66. GRB 061222B: Observation with the KANATA 1.5m telescope
  67. GRB061222B: Swift-XRT Refined Analysis
  68. GRB 061222A: Observation with the KANATA 1.5m telescope
  69. GRB 061222B: BOOTES-IR optical observations
  70. GRB 061222B: SARA upper limit
  71. GRB 061222A: Swift-XRT refined analysis
  72. GRB 061217: Magellan host galaxy redshift
  73. GRB 061222A, Swift-BAT refined analysis
  74. GRB 061222B: REM NIR/optical observations
  75. GRB 061222b: Refined redshift
  76. GRB 061222b, SMARTS optical/IR afterglow observations
  77. GRB 061222B: TAROT La Silla observatory afterglow observation
  78. GRB 061222B: TAROT La Silla observatory optical observations
  79. GRB 061222b: Magellan redshift
  80. GRB 061222B: Swift detection of a burst
  81. GRB 061222b: optical afterglow
  82. GRB 061222A: Prompt ROTSE-III Optical Limits
  83. GRB 061222: Swift detection of a burst
  84. GRB 061217: Astrometry-Corrected XRT Position
  85. GRB 061201: Magellan redshift of nearby galaxy
  86. GRB 061217: Confirmation of host candidate
  87. GRB 061217: Object ib GCN 5948 is a star
  88. GRB 061217: Extended object in the revised XRT error circle
  89. GRB 061217, Candidate host galaxy
  90. GRB 061217 - Swift/XRT position correction
  91. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  92. GRB 061201: Correction to GCN 5944
  93. GRB 061201: Magellan Redshift of nearby Abell cluster
  94. GRB 061218: TAROT La Silla observatory optical observations
  95. GRB 061217: TAROT Calern observatory optical observations
  96. GRB 061218: TORTOREM optical upper limits
  97. GRB 061218, Swift-BAT refined analysis
  98. GRB061217: VLT NIR observations
  99. GRB 061218, SMARTS optical/IR observations
  100. GRB 061218: REM prompt observations

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