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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"

18325 results found.

  1. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  2. GRB 260907A: SVOM/GRM observation
  3. GRB 260909A: CrAO and AbAO optical upper limits
  4. GRB 260909A: KAIT optical upper limit
  5. GRB 260903A: Swift-XRT observations
  6. GRB 260909A: OHP/T193 z-band upper limit
  7. GRB 260909A: VLT optical and near-infrared upper limits
  8. GRB 260909A: EP-FXT follow-up observation
  9. EP260806a: NOEMA detection
  10. EP260623a: NOEMA detections
  11. GRB 260909A: Mondy optical observations and afterglow candidate
  12. GRB 260909A: Xinglong 2.16m optical upper limit
  13. GRB 260909A: SVOM/C-GFT optical upper limit
  14. GRB 260909A: SVOM detection of a burst
  15. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  16. GRB 260903A: SAO RAS optical upper limit
  17. The EP-WXT trigger 01709305715 is likely a flaring star
  18. EP260903a: EP-FXT follow-up observation
  19. The EP-WXT trigger 01709302592 is likely a flaring star
  20. GRB 260903A: J-band upper limit with WINTER
  21. GRB260903A: Liverpool Telescope optical observations
  22. GRB 260903A: SAO RAS optical observations
  23. EP260903a: EP-WXT detection of a fast X-ray transient
  24. GRB 260830A: Insight-HXMT/HE detection
  25. GRB 260903A: EP-FXT follow-up observation
  26. GRB 260903A: OHP/T193 optical afterglow detection
  27. NuSTAR Transient 260828: SOAR Optical Upper Limits
  28. GRB 260903A: LCO optical counterpart detection
  29. EP260901a: SVOM/VT optical upper limits
  30. EP260901a: EP-FXT follow-up observation
  31. GRB 260829A: SVOM/GRM observation
  32. GRB 260818A: ATCA detection of a candidate radio counterpart
  33. EP260830a: EP-FXT follow-up observation
  34. EP260901a: Global MASTER-Net observations report
  35. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  36. NuSTAR Transient 260828: LCO Optical Upper Limits
  37. EP260901a: EP-WXT detection of a fast X-ray transient
  38. GRB 260831B: EP-FXT follow-up observation
  39. GRB 260831B: LCO optical upper limits
  40. EP260830a: EP-WXT detection of a fast X-ray transient
  41. GRB 260827A: SVOM/GRM observation
  42. GRB 260831B: SVOM detection of a possible burst
  43. GRB 260825A: SVOM/GRM observation of a long burst
  44. GRB 260818B: Further EP-FXT observation
  45. GRB 260818B: VLT optical and nIR observations
  46. GRB 260818B: TNG NIR observations
  47. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  48. GRB 260818B: 6 GHz VLA observations
  49. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  50. GRB 260808B: SAO RAS observations of the optical rebrightening
  51. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  52. GRB 260822A: EP/FXT follow-up observations
  53. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  54. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  55. EP260822a: EP-FXT non-detection and upper limit
  56. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  57. EP260822a: Einstein Probe detection of a fast X-ray transient
  58. GRB 260822A: LCO optical upper limits
  59. The EP-WXT trigger 01709287395 is likely a flaring star
  60. GRB 260822A: GROWTH-India Telescope Upper Limits
  61. GRB 260818B: VLA radio observations
  62. GRB 260818B: SVOM/C-GFT optical upper limit
  63. The EP-WXT trigger 01709286204 is likely a flaring star
  64. EP detected a brightening of LMXB 1ES 1735-26.9
  65. GRB 260818B: EP-FXT follow-up observation
  66. GRB 260818A: J-band observations with WINTER
  67. GRB 260818B: NOT optical upper limits
  68. GRB 260810A: SVOM/GRM observation
  69. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  70. GRB260818A: EP-FXT follow-up observation
  71. GRB 260818B: LCO optical upper limits
  72. EP260806a: SAO RAS multicolor optical observations
  73. GRB 260818A: LCO optical upper limits
  74. EP260812a: AbAO optical upper limit
  75. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  76. EP260806a: NUTTELA-TAO optical observations
  77. The EP-WXT trigger 01709281429 is likely a flaring star
  78. EP260812a: AZT-22 optical upper limit
  79. EP260806a: WFST optical observations
  80. The EP-WXT trigger 01709280562 is likely a flaring star
  81. EP260812b: Optical upper limit with Kinder
  82. The EP-WXT trigger 01709279838 is likely a flaring star
  83. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  84. GRB 260808B: Liverpool Telescope further optical observations
  85. EP260812a: NOT and Liverpool Telescope upper limits:
  86. EP260812b: Liverpool Telescope observations
  87. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  88. EP260812a: SVOM/C-GFT optical upper limit
  89. EP260812b: COLIBRÍ optical observations
  90. EP260812b: SVOM/VT optical observation
  91. GRB 260808A: SVOM/GRM observation
  92. EP260812b: Einstein Probe detection of an X-ray transient
  93. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  94. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  95. EP260812a: Einstein Probe detection of an X-ray transient
  96. GRB 260809A: SAO RAS optical observations
  97. GRB 260808B: SAO RAS optical observations
  98. EP260806a: MAO/AZT-22 optical observations
  99. GRB260808B: MAO/AZT-22 optical observations
  100. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search

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