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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"

23252 results found.

  1. GRB 260818B: 6 GHz VLA observations
  2. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  3. GRB 260808B: SAO RAS observations of the optical rebrightening
  4. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  5. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  6. EP260822a: EP-FXT non-detection and upper limit
  7. GRB 260822A: GOTO optical counterpart detection
  8. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  9. EP260822a: Einstein Probe detection of a fast X-ray transient
  10. GRB 260822A: LCO optical upper limits
  11. GRB 260822A: GROWTH-India Telescope Upper Limits
  12. GRB 260818B: VLA radio observations
  13. GRB 260818B: SVOM/C-GFT optical upper limit
  14. EP detected a brightening of LMXB 1ES 1735-26.9
  15. GRB 260818A: J-band observations with WINTER
  16. GRB 260818B: NOT optical upper limits
  17. GRB 260810A: SVOM/GRM observation
  18. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  19. GRB 260818B: LCO optical upper limits
  20. EP260806a: SAO RAS multicolor optical observations
  21. GRB 260818A: LCO optical upper limits
  22. EP260812a: AbAO optical upper limit
  23. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  24. EP260806a: NUTTELA-TAO optical observations
  25. EP260812a: AZT-22 optical upper limit
  26. EP260806a: WFST optical observations
  27. EP260812b: Optical upper limit with Kinder
  28. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  29. GRB 260808B: Liverpool Telescope further optical observations
  30. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  31. EP260812a: NOT and Liverpool Telescope upper limits:
  32. EP260812b: Liverpool Telescope observations
  33. EP260812b: GOTO detection of the optical counterpart
  34. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  35. EP260812a: SVOM/C-GFT optical upper limit
  36. EP260812b: COLIBRÍ optical observations
  37. EP260812b: SVOM/VT optical observation
  38. GRB 260808A: SVOM/GRM observation
  39. EP260812b: Einstein Probe detection of an X-ray transient
  40. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  41. GRB 260810A: Glowbug gamma-ray detection
  42. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  43. GRB 260810A: AstroSat CZTI detection of a long burst
  44. EP260812a: Einstein Probe detection of an X-ray transient
  45. GRB 260809A: SAO RAS optical observations
  46. GRB 260808B: SAO RAS optical observations
  47. GRB 260808B: SVOM/VT optical re-brightening at day 3
  48. EP260806a: MAO/AZT-22 optical observations
  49. GRB260808B: MAO/AZT-22 optical observations
  50. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  51. GRB 260809A: J-band upper limit with WINTER
  52. GRB 260806A: Glowbug gamma-ray detection
  53. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  54. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  55. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  56. GRB 260809A: NOT optical observations
  57. GRB260809A: MAO/AZT-22 optical observations
  58. GRB260809A: OHP/T193 optical observations
  59. EP260809a: J-band upper limit with WINTER
  60. GRB 260808B: J-band upper limit with WINTER
  61. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  62. GRB 260809A: SVOM detection of a faint burst
  63. GRB 260808B: Liverpool Telescope optical observations
  64. GRB 260808B: NOT optical observations
  65. GRB 260808B: LCO optical observations
  66. EP260809a: COLIBRÍ optical observations
  67. EP260809a: LCO optical observation
  68. EP260809a: OHP/T193 optical observations
  69. GRB260808B: OHP/T193 optical observations
  70. EP260809a: Einstein Probe detection of an X-ray transient
  71. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  72. GRB 260808B: SVOM/VT optical candidate from VHF data
  73. GRB 260808B: SVOM detection of a faint burst
  74. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  75. EP260806a: COLIBRÍ optical observations
  76. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  77. EP260806a: SVOM/VT optical observation
  78. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  79. EP260806a: OSIRIS+/GTC redshift z=0.089
  80. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  81. EP260806a: LCO likely optical counterpart
  82. EP260806a: Einstein Probe detection of an X-ray transient
  83. GRB 260715A: cubesat Avion detection
  84. GRB 260709A: cubesat Avion detection
  85. GRB 260708A: cubesat Avion detection
  86. GRB 260730B: Glowbug gamma-ray detection
  87. GRB 260805C: Glowbug gamma-ray detection
  88. GRB 260805B: Glowbug gamma-ray detection
  89. GRB 260804A: Glowbug gamma-ray detection
  90. GRB 260803A: Fermi GBM Final Real-time Localization
  91. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  92. GRB 260802A: SVOM/VT optical upper limits from VHF data
  93. GRB 260802A: LCO optical upper limits
  94. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  95. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  96. GRB 260731A: AstroSat CZTI detection of a long burst
  97. GRB 260730B: AstroSat CZTI detection
  98. EP260731a: COLIBRÍ optical upper limit
  99. EP260731a: NOT optical upper limit
  100. EP260731a: Einstein Probe detection of an X-ray transient

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