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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"

18332 results found.

  1. GRB 260914A: LCO optical observation
  2. GRB 260914A: SVOM/C-GFT optical observations
  3. GRB 260914A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  4. GRB 260914A: SVOM detection of a burst
  5. GRB 260913A: SVOM trigger sb26091302 is not an astrophysical event
  6. GRB 260913A: SVOM/C-GFT optical upper limit
  7. GRB 260913A: SVOM detection of a faint burst
  8. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  9. GRB 260907A: SVOM/GRM observation
  10. GRB 260909A: CrAO and AbAO optical upper limits
  11. GRB 260909A: KAIT optical upper limit
  12. GRB 260903A: Swift-XRT observations
  13. GRB 260909A: OHP/T193 z-band upper limit
  14. GRB 260909A: VLT optical and near-infrared upper limits
  15. GRB 260909A: EP-FXT follow-up observation
  16. EP260806a: NOEMA detection
  17. EP260623a: NOEMA detections
  18. GRB 260909A: Mondy optical observations and afterglow candidate
  19. GRB 260909A: Xinglong 2.16m optical upper limit
  20. GRB 260909A: SVOM/C-GFT optical upper limit
  21. GRB 260909A: SVOM detection of a burst
  22. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  23. GRB 260903A: SAO RAS optical upper limit
  24. The EP-WXT trigger 01709305715 is likely a flaring star
  25. EP260903a: EP-FXT follow-up observation
  26. The EP-WXT trigger 01709302592 is likely a flaring star
  27. GRB 260903A: J-band upper limit with WINTER
  28. GRB260903A: Liverpool Telescope optical observations
  29. GRB 260903A: SAO RAS optical observations
  30. EP260903a: EP-WXT detection of a fast X-ray transient
  31. GRB 260830A: Insight-HXMT/HE detection
  32. GRB 260903A: EP-FXT follow-up observation
  33. GRB 260903A: OHP/T193 optical afterglow detection
  34. NuSTAR Transient 260828: SOAR Optical Upper Limits
  35. GRB 260903A: LCO optical counterpart detection
  36. EP260901a: SVOM/VT optical upper limits
  37. EP260901a: EP-FXT follow-up observation
  38. GRB 260829A: SVOM/GRM observation
  39. GRB 260818A: ATCA detection of a candidate radio counterpart
  40. EP260830a: EP-FXT follow-up observation
  41. EP260901a: Global MASTER-Net observations report
  42. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  43. NuSTAR Transient 260828: LCO Optical Upper Limits
  44. EP260901a: EP-WXT detection of a fast X-ray transient
  45. GRB 260831B: EP-FXT follow-up observation
  46. GRB 260831B: LCO optical upper limits
  47. EP260830a: EP-WXT detection of a fast X-ray transient
  48. GRB 260827A: SVOM/GRM observation
  49. GRB 260831B: SVOM detection of a possible burst
  50. GRB 260825A: SVOM/GRM observation of a long burst
  51. GRB 260818B: Further EP-FXT observation
  52. GRB 260818B: VLT optical and nIR observations
  53. GRB 260818B: TNG NIR observations
  54. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  55. GRB 260818B: 6 GHz VLA observations
  56. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  57. GRB 260808B: SAO RAS observations of the optical rebrightening
  58. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  59. GRB 260822A: EP/FXT follow-up observations
  60. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  61. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  62. EP260822a: EP-FXT non-detection and upper limit
  63. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  64. EP260822a: Einstein Probe detection of a fast X-ray transient
  65. GRB 260822A: LCO optical upper limits
  66. The EP-WXT trigger 01709287395 is likely a flaring star
  67. GRB 260822A: GROWTH-India Telescope Upper Limits
  68. GRB 260818B: VLA radio observations
  69. GRB 260818B: SVOM/C-GFT optical upper limit
  70. The EP-WXT trigger 01709286204 is likely a flaring star
  71. EP detected a brightening of LMXB 1ES 1735-26.9
  72. GRB 260818B: EP-FXT follow-up observation
  73. GRB 260818A: J-band observations with WINTER
  74. GRB 260818B: NOT optical upper limits
  75. GRB 260810A: SVOM/GRM observation
  76. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  77. GRB260818A: EP-FXT follow-up observation
  78. GRB 260818B: LCO optical upper limits
  79. EP260806a: SAO RAS multicolor optical observations
  80. GRB 260818A: LCO optical upper limits
  81. EP260812a: AbAO optical upper limit
  82. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  83. EP260806a: NUTTELA-TAO optical observations
  84. The EP-WXT trigger 01709281429 is likely a flaring star
  85. EP260812a: AZT-22 optical upper limit
  86. EP260806a: WFST optical observations
  87. The EP-WXT trigger 01709280562 is likely a flaring star
  88. EP260812b: Optical upper limit with Kinder
  89. The EP-WXT trigger 01709279838 is likely a flaring star
  90. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  91. GRB 260808B: Liverpool Telescope further optical observations
  92. EP260812a: NOT and Liverpool Telescope upper limits:
  93. EP260812b: Liverpool Telescope observations
  94. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  95. EP260812a: SVOM/C-GFT optical upper limit
  96. EP260812b: COLIBRÍ optical observations
  97. EP260812b: SVOM/VT optical observation
  98. GRB 260808A: SVOM/GRM observation
  99. EP260812b: Einstein Probe detection of an X-ray transient
  100. EP trigger #01709278129 (EP260812b?): NOT optical counterpart

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