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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"

20246 results found.

  1. GRB 260909A: CrAO and AbAO optical upper limits
  2. GRB 260909A: SVOM/ECLAIRs refined analysis
  3. GRB 260909A: KAIT optical upper limit
  4. GRB 260903A: Swift-XRT observations
  5. GRB 260909A: OHP/T193 z-band upper limit
  6. GRB 260909A: VLT optical and near-infrared upper limits
  7. EP260806a: NOEMA detection
  8. EP260623a: NOEMA detections
  9. GRB 260909A: Mondy optical observations and afterglow candidate
  10. GRB 260909A: Xinglong 2.16m optical upper limit
  11. GRB 260909A: SVOM/C-GFT optical upper limit
  12. GRB 260909A: SVOM detection of a burst
  13. GRB 260903A: SAO RAS optical upper limit
  14. GRB 260903A: J-band upper limit with WINTER
  15. GRB 260903A: SVOM/ECLAIRs refined analysis
  16. GRB260903A: Liverpool Telescope optical observations
  17. GRB 260903A: SAO RAS optical observations
  18. EP260903a: EP-WXT detection of a fast X-ray transient
  19. GRB 260903A: OHP/T193 optical afterglow detection
  20. NuSTAR Transient 260828: SOAR Optical Upper Limits
  21. GRB 260831A: GECAM-B observation
  22. GRB 260903A: LCO optical counterpart detection
  23. EP260901a: SVOM/VT optical upper limits
  24. EP260901a: EP-FXT follow-up observation
  25. Konus-Wind detection of GRB 260829A
  26. GRB 260829A: SVOM/GRM observation
  27. GRB 260818A: ATCA detection of a candidate radio counterpart
  28. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  29. NuSTAR Transient 260828: LCO Optical Upper Limits
  30. EP260901a: EP-WXT detection of a fast X-ray transient
  31. GRB 260831B: LCO optical upper limits
  32. EP260830a: EP-WXT detection of a fast X-ray transient
  33. GRB 260827A: SVOM/GRM observation
  34. GRB 260831B: SVOM detection of a possible burst
  35. EP260727a: ATCA 10 GHz detection
  36. GRB 260825A: SVOM/GRM observation of a long burst
  37. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  38. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  39. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  40. GRB 260818B: Further EP-FXT observation
  41. GRB 260818B: VLT optical and nIR observations
  42. GRB 260818B: TNG NIR observations
  43. GRB 260818B: 6 GHz VLA observations
  44. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  45. GRB 260808B: SAO RAS observations of the optical rebrightening
  46. GRB 260822A: SVOM/ECLAIRs refined analysis
  47. GRB 260809A: SVOM/ECLAIRs refined analysis
  48. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  49. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  50. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  51. EP260822a: EP-FXT non-detection and upper limit
  52. GRB 260822A: GOTO optical counterpart detection
  53. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  54. EP260822a: Einstein Probe detection of a fast X-ray transient
  55. GRB 260822A: LCO optical upper limits
  56. GRB 260822A: GROWTH-India Telescope Upper Limits
  57. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  58. GRB 260818B: SVOM/C-GFT optical upper limit
  59. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  60. EP detected a brightening of LMXB 1ES 1735-26.9
  61. GRB 260818A: J-band observations with WINTER
  62. GRB 260818B: SVOM/ECLAIRs refined analysis
  63. GRB 260818A: SVOM/ECLAIRs refined analysis
  64. GRB 260818B: NOT optical upper limits
  65. GRB 260810A: SVOM/GRM observation
  66. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  67. GRB 260818B: LCO optical upper limits
  68. EP260806a: SAO RAS multicolor optical observations
  69. GRB 260818A: LCO optical upper limits
  70. EP260812a: AbAO optical upper limit
  71. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  72. EP260806a: SVOM/ECLAIRs detection through targeted search
  73. EP260806a: NUTTELA-TAO optical observations
  74. EP260812a: AZT-22 optical upper limit
  75. EP260806a: WFST optical observations
  76. EP260812b: Optical upper limit with Kinder
  77. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  78. GRB 260808B: Liverpool Telescope further optical observations
  79. EP260812a: NOT and Liverpool Telescope upper limits:
  80. EP260812b: Liverpool Telescope observations
  81. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  82. EP260812a: SVOM/C-GFT optical upper limit
  83. EP260812b: COLIBRÍ optical observations
  84. EP260812b: SVOM/VT optical observation
  85. GRB 260808A: SVOM/GRM observation
  86. EP260812b: Einstein Probe detection of an X-ray transient
  87. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  88. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  89. GRB 260810A: AstroSat CZTI detection of a long burst
  90. EP260812a: Einstein Probe detection of an X-ray transient
  91. GRB 260809A: SAO RAS optical observations
  92. GRB 260808B: SAO RAS optical observations
  93. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  94. GRB 260807A: SVOM/ECLAIRs refined analysis
  95. EP260806a: MAO/AZT-22 optical observations
  96. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  97. GRB260808B: MAO/AZT-22 optical observations
  98. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  99. GRB 260809A: J-band upper limit with WINTER
  100. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07

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