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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"

16084 results found.

  1. GRB 260818A: Continued ATCA observations
  2. GRB 260913A: SVOM/C-GFT optical upper limit
  3. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  4. GRB 260907A: SVOM/GRM observation
  5. GRB 260909A: CrAO and AbAO optical upper limits
  6. GRB 260910B: GOTO tentative optical counterpart candidates
  7. GRB 260909A: KAIT optical upper limit
  8. GRB 260903A: Swift-XRT observations
  9. EP260806a: VLA+ALMA radio detections
  10. GRB 260909A: VLT optical and near-infrared upper limits
  11. GRB 260909A: EP-FXT follow-up observation
  12. GRB 260909A: SVOM/VT optical upper limits
  13. GRB 260909A: Mondy optical observations and afterglow candidate
  14. GRB 260909A: Xinglong 2.16m optical upper limit
  15. GRB 260909A: SVOM/C-GFT optical upper limit
  16. GRB 260903A: SAO RAS optical upper limit
  17. GRB 260903A: J-band upper limit with WINTER
  18. GRB260903A: Liverpool Telescope optical observations
  19. GRB 260903A: SAO RAS optical observations
  20. EP260903a: EP-WXT detection of a fast X-ray transient
  21. GRB 260903A: OHP/T193 optical afterglow detection
  22. GRB 260903A: NOT optical observations and afterglow fading
  23. NuSTAR Transient 260828: SOAR Optical Upper Limits
  24. GRB 260903A: LCO optical observations
  25. GRB 260903A: SVOM/VT optical candidate
  26. GRB 260903A: Retraction of optical counterpart of GCN 45501
  27. GRB 260903A: LCO optical counterpart detection
  28. GRB 260903A: SVOM detection of a soft faint burst
  29. EP260901a: SVOM/VT optical upper limits
  30. GRB 260829A: SVOM/GRM observation
  31. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  32. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  33. NuSTAR Transient 260828: LCO Optical Upper Limits
  34. GRB 260831B: LCO optical upper limits
  35. GRB 260827A: SVOM/GRM observation
  36. EP260727a: ATCA 10 GHz detection
  37. GRB 260825A: SVOM/GRM observation of a long burst
  38. GRB 260818B: Further EP-FXT observation
  39. GRB 260818B: VLT optical and nIR observations
  40. GRB 260818B: 6 GHz VLA observations
  41. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  42. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  43. GRB 260808B: SAO RAS observations of the optical rebrightening
  44. GRB 260822A: SVOM/VT optical upper limits
  45. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  46. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  47. GRB 260822A: GOTO optical counterpart detection
  48. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  49. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  50. GRB 260822A: LCO optical upper limits
  51. GRB 260822A: GROWTH-India Telescope Upper Limits
  52. GRB 260822A: GOTO optical upper limit
  53. GRB 260818B: SVOM/C-GFT optical upper limit
  54. GRB 260818B: SVOM/GRM observation
  55. GRB 260818B: NOT optical upper limits
  56. GRB 260810A: SVOM/GRM observation
  57. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  58. GRB 260818B: LCO optical upper limits
  59. GRB 260818B: SVOM detection of a short burst
  60. EP260806a: SAO RAS multicolor optical observations
  61. GRB 260818A: LCO optical upper limits
  62. EP260812a: AbAO optical upper limit
  63. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  64. EP260806a: NUTTELA-TAO optical observations
  65. EP260812a: AZT-22 optical upper limit
  66. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  67. EP260806a: WFST optical observations
  68. EP260812b: Optical upper limit with Kinder
  69. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  70. GRB 260808B: Liverpool Telescope further optical observations
  71. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  72. EP260812a: NOT and Liverpool Telescope upper limits:
  73. EP260812b: Liverpool Telescope observations
  74. EP260812b: GOTO detection of the optical counterpart
  75. EP260812a: SVOM/C-GFT optical upper limit
  76. EP260812b: COLIBRÍ optical observations
  77. EP260812b: SVOM/VT optical observation
  78. GRB 260808A: SVOM/GRM observation
  79. EP260812b: Einstein Probe detection of an X-ray transient
  80. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  81. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  82. GRB 260809A: SAO RAS optical observations
  83. GRB 260808B: SAO RAS optical observations
  84. GRB 260808B: SVOM/VT optical re-brightening at day 3
  85. EP260806a: MAO/AZT-22 optical observations
  86. GRB260808B: MAO/AZT-22 optical observations
  87. GRB 260809A: J-band upper limit with WINTER
  88. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  89. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  90. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  91. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  92. GRB 260809A: NOT optical observations
  93. GRB260809A: MAO/AZT-22 optical observations
  94. GRB260809A: OHP/T193 optical observations
  95. GRB 260809A: SVOM/VT optical counterpart
  96. EP260809a: J-band upper limit with WINTER
  97. GRB 260808B: J-band upper limit with WINTER
  98. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  99. GRB 260808B: Liverpool Telescope optical observations
  100. GRB 260808B: NOT optical observations

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