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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"

23249 results found.

  1. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  2. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  3. EP260822a: EP-FXT non-detection and upper limit
  4. GRB 260822A: GOTO optical counterpart detection
  5. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  6. EP260822a: Einstein Probe detection of a fast X-ray transient
  7. GRB 260822A: LCO optical upper limits
  8. GRB 260822A: GROWTH-India Telescope Upper Limits
  9. GRB 260818B: VLA radio observations
  10. GRB 260818B: SVOM/C-GFT optical upper limit
  11. EP detected a brightening of LMXB 1ES 1735-26.9
  12. GRB 260818A: J-band observations with WINTER
  13. GRB 260818B: NOT optical upper limits
  14. GRB 260810A: SVOM/GRM observation
  15. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  16. GRB 260818B: LCO optical upper limits
  17. EP260806a: SAO RAS multicolor optical observations
  18. GRB 260818A: LCO optical upper limits
  19. EP260812a: AbAO optical upper limit
  20. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  21. EP260806a: NUTTELA-TAO optical observations
  22. EP260812a: AZT-22 optical upper limit
  23. EP260806a: WFST optical observations
  24. EP260812b: Optical upper limit with Kinder
  25. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  26. GRB 260808B: Liverpool Telescope further optical observations
  27. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  28. EP260812a: NOT and Liverpool Telescope upper limits:
  29. EP260812b: Liverpool Telescope observations
  30. EP260812b: GOTO detection of the optical counterpart
  31. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  32. EP260812a: SVOM/C-GFT optical upper limit
  33. EP260812b: COLIBRÍ optical observations
  34. EP260812b: SVOM/VT optical observation
  35. GRB 260808A: SVOM/GRM observation
  36. EP260812b: Einstein Probe detection of an X-ray transient
  37. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  38. GRB 260810A: Glowbug gamma-ray detection
  39. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  40. GRB 260810A: AstroSat CZTI detection of a long burst
  41. EP260812a: Einstein Probe detection of an X-ray transient
  42. GRB 260809A: SAO RAS optical observations
  43. GRB 260808B: SAO RAS optical observations
  44. GRB 260808B: SVOM/VT optical re-brightening at day 3
  45. EP260806a: MAO/AZT-22 optical observations
  46. GRB260808B: MAO/AZT-22 optical observations
  47. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  48. GRB 260809A: J-band upper limit with WINTER
  49. GRB 260806A: Glowbug gamma-ray detection
  50. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  51. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  52. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  53. GRB 260809A: NOT optical observations
  54. GRB260809A: MAO/AZT-22 optical observations
  55. GRB260809A: OHP/T193 optical observations
  56. EP260809a: J-band upper limit with WINTER
  57. GRB 260808B: J-band upper limit with WINTER
  58. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  59. GRB 260809A: SVOM detection of a faint burst
  60. GRB 260808B: Liverpool Telescope optical observations
  61. GRB 260808B: NOT optical observations
  62. GRB 260808B: LCO optical observations
  63. EP260809a: COLIBRÍ optical observations
  64. EP260809a: LCO optical observation
  65. EP260809a: OHP/T193 optical observations
  66. GRB260808B: OHP/T193 optical observations
  67. EP260809a: Einstein Probe detection of an X-ray transient
  68. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  69. GRB 260808B: SVOM/VT optical candidate from VHF data
  70. GRB 260808B: SVOM detection of a faint burst
  71. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  72. EP260806a: COLIBRÍ optical observations
  73. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  74. EP260806a: SVOM/VT optical observation
  75. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  76. EP260806a: OSIRIS+/GTC redshift z=0.089
  77. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  78. EP260806a: LCO likely optical counterpart
  79. EP260806a: Einstein Probe detection of an X-ray transient
  80. GRB 260715A: cubesat Avion detection
  81. GRB 260709A: cubesat Avion detection
  82. GRB 260708A: cubesat Avion detection
  83. GRB 260730B: Glowbug gamma-ray detection
  84. GRB 260805C: Glowbug gamma-ray detection
  85. GRB 260805B: Glowbug gamma-ray detection
  86. GRB 260804A: Glowbug gamma-ray detection
  87. GRB 260803A: Fermi GBM Final Real-time Localization
  88. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  89. GRB 260802A: SVOM/VT optical upper limits from VHF data
  90. GRB 260802A: LCO optical upper limits
  91. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  92. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  93. GRB 260731A: AstroSat CZTI detection of a long burst
  94. GRB 260730B: AstroSat CZTI detection
  95. EP260731a: COLIBRÍ optical upper limit
  96. EP260731a: NOT optical upper limit
  97. EP260731a: Einstein Probe detection of an X-ray transient
  98. GRB 260727A: SVOM/ECLAIRs refined analysis
  99. EP260728a: COLIBRÍ optical upper limit
  100. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin

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